How Biological Diversity Evolves MACROEVOLUTION Chapter 14 How Biological Diversity Evolves MACROEVOLUTION

Biology and Society: The Sixth Mass Extinction Over the past 600 million years the fossil record reveals five periods of extinction when 50–90% of living species suddenly died out. © 2010 Pearson Education, Inc.

Figure 14.0 Mountain gorillas

Our current rate of extinction, over the past 400 years, indicates that we may be living in, and contributing to, the sixth mass extinction period. Mass extinctions: Pave the way for the evolution of new and diverse forms, but Take millions of years for Earth to recover The most “famous” mass-extinction is the K-T Mass Extinction which included the extinction of the dinosaurs (except birds). This will be discussed in Chapter 17.

MACROEVOLUTION AND THE DIVERSITY OF LIFE Encompasses the major biological changes evident in the fossil record Includes the formation of new species Student Misconceptions and Concerns 1. Students might not realize that evolutionary change includes (a) linear events, in which a species changes over time, and (b) branching events, which produce new species and diversity. Some students expect that when new species evolve, they replace their ancestors. Questions such as “If we came from chimps, why are there still chimps alive today” reveal this, and other, misunderstandings. Teaching Tips 1. Before lecturing about speciation, consider a short writing assignment. Have students work individually or in small groups, without the benefit of books, to define a species. 2. Students might not realize that entire categories of animals have come and gone. Once abundant trilobites and non-avian dinosaurs are now extinct. Birds and mammals are relatively recent additions. Such examples of macroevolution are apparent in the fossil record.

THE ORIGIN OF SPECIES Species is a Latin word meaning: “Kind” or “Appearance.” Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

What Is a Species? The biological species concept defines a species as “A group of populations whose members have the potential to interbreed and produce fertile offspring” It is also sometimes stated like this: “A group of populations whose members share a common gene pool and are potentially interbreeding” Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

Speciation: Is the focal point of macroevolution May occur based on two contrasting patterns, non-branching and branching. Student Misconceptions and Concerns 1. Students might not realize that evolutionary change includes (a) linear events, in which a species changes over time, and (b) branching events, which produce new species and diversity. Some students expect that when new species evolve, they replace their ancestors. Questions such as “If we came from chimps, why are there still chimps alive today” reveal this, and other, misunderstandings. Teaching Tips 1. Before lecturing about speciation, consider a short writing assignment. Have students work individually or in small groups, without the benefit of books, to define a species. 2. Students might not realize that entire categories of animals have come and gone. Once abundant trilobites and non-avian dinosaurs are now extinct. Birds and mammals are relatively recent additions. Such examples of macroevolution are apparent in the fossil record.

In non-branching evolution: A population transforms but does not create a new species Actually, it may, but the hypothesis is usually untestable. Student Misconceptions and Concerns 1. Students might not realize that evolutionary change includes (a) linear events, in which a species changes over time, and (b) branching events, which produce new species and diversity. Some students expect that when new species evolve, they replace their ancestors. Questions such as “If we came from chimps, why are there still chimps alive today” reveal this, and other, misunderstandings. Teaching Tips 1. Before lecturing about speciation, consider a short writing assignment. Have students work individually or in small groups, without the benefit of books, to define a species. 2. Students might not realize that entire categories of animals have come and gone. Once abundant trilobites and non-avian dinosaurs are now extinct. Birds and mammals are relatively recent additions. Such examples of macroevolution are apparent in the fossil record.

In branching evolution, one or more new species branch from a parent species that may: Continue to exist in much the same form or Change considerably Student Misconceptions and Concerns 1. Students might not realize that evolutionary change includes (a) linear events, in which a species changes over time, and (b) branching events, which produce new species and diversity. Some students expect that when new species evolve, they replace their ancestors. Questions such as “If we came from chimps, why are there still chimps alive today” reveal this, and other, misunderstandings. Teaching Tips 1. Before lecturing about speciation, consider a short writing assignment. Have students work individually or in small groups, without the benefit of books, to define a species. 2. Students might not realize that entire categories of animals have come and gone. Once abundant trilobites and non-avian dinosaurs are now extinct. Birds and mammals are relatively recent additions. Such examples of macroevolution are apparent in the fossil record.

Similarity between different species Diversity within one species Figure 14.2 The biological species concept is based on reproductive compatibility Similarity between different species Diversity within one species Figure 14.2

The biological species concept cannot be applied in all situations, including: Fossils Asexual organisms Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

Reproductive Barriers/Isolating Mechanisms between Species What’s the logic of isolating mechanisms/reproductive barriers? ? Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

Reproductive Barriers between Species Prezygotic barriers prevent mating or fertilization between species. Below are some examples you can see at MasteringBiology Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies. Video: Albatross Courtship Ritual Video: Blue-footed Boobies Courtship Ritual Video: Giraffe Courtship Ritual

Figure 14.3 INDIVIDUALS OF DIFFERENT SPECIES Prezygotic Barriers Temporal isolation Habitat isolation Behavioral isolation MATING ATTEMPT Mechanical isolation Gametic isolation FERTILIZATION (ZYGOTE FORMS) Postzygotic Barriers Figure 14.3 Reproductive barriers between closely related species Reduced hybrid viability Reduced hybrid fertility Hybrid breakdown VIABLE, FERTILE OFFSPRING Figure 14.3

PREZYGOTIC BARRIERS Temporal Isolation Habitat Isolation Behavioral Isolation Mechanical Isolation Gametic Isolation Figure 14.4 Prezygotic barriers Figure 14.4

Postzygotic barriers operate if: Interspecies mating occurs and Hybrid zygotes form Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

Figure 14.3 INDIVIDUALS OF DIFFERENT SPECIES Prezygotic Barriers Temporal isolation Habitat isolation Behavioral isolation MATING ATTEMPT Mechanical isolation Gametic isolation FERTILIZATION (ZYGOTE FORMS) Postzygotic Barriers Figure 14.3 Reproductive barriers between closely related species Reduced hybrid viability Reduced hybrid fertility Hybrid breakdown VIABLE, FERTILE OFFSPRING Figure 14.3

Postzygotic barriers include: Reduced hybrid viability Reduced hybrid fertility Hybrid breakdown Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

POSTZYGOTIC BARRIERS Reduced Hybrid Viability Reduced Hybrid Fertility Hybrid Breakdown Horse Donkey Figure 14.5 Postzygotic barriers Mule Figure 14.5

Mechanisms of Speciation A key event in the potential origin of a species occurs when a population is severed from other populations of the parent species. Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

Species can form by: Allopatric speciation, due to geographic isolation Sympatric speciation, without geographic isolation Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

Allopatric speciation Simpatric speciation Figure 14.6 Two modes of speciation Allopatric speciation Simpatric speciation Figure 14.6

Allopatric Speciation Geologic processes can: Fragment a population into two or more isolated populations Contribute to allopatric speciation Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies. Video: Lava Flow Video: Volcanic Eruption Video: Grand Canyon

Ammospermophilus harrisii Ammospermophilus leucurus Figure 14.7 Allopatric speciation of antelope squirrels on opposite rims of the Grand Canyon Figure 14.7

Speciation occurs only with the evolution of reproductive barriers between the isolated population and its parent population. Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

Populations Populations become become allopatric sympatric Populations interbreed Gene pools merge: No speciation Populations cannot interbreed Geographic barrier Figure 14.8 Has speciation occurred during geographic isolation? Reproductive isolation: Speciation has occurred Time Figure 14.8

Sympatric Speciation Sympatric speciation occurs: While the new species and old species live in the same time and place If a genetic change produces a reproductive barrier between the new and old species Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

Polyploids can: Originate from accidents during cell division Result from the hybridization of two parent species Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

Many domesticated plants are the result of sympatric speciation, including: Oats Potatoes Bananas Peanuts Apples Coffee Wheat Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

Sterile hybrid (14 chromosomes) Sterile hybrid (21 chromosomes) Domesticated Triticum monococcum (14 chromosomes) Wild Triticum (14 chromosomes) AA BB AB Sterile hybrid (14 chromosomes) T. turgidum Emmer wheat (28 chromosomes) AA BB DD Wild T. tauschii (14 chromosomes) Figure 14.9 The evolution of wheat (Step 4) ABD Sterile hybrid (21 chromosomes) T. aestivum Bread wheat (42 chromosomes) AA BB DD Figure 14.9-4

Figure 14.9a Wheat Figure 14.9a

What Is the Tempo of Speciation? There are two contrasting models of the pace of evolution: The gradual model, in which big changes (speciations) occur by the steady accumulation of many small changes The punctuated equilibria model, in which there are Long periods of little change, equilibrium, punctuated by Abrupt episodes of speciation Student Misconceptions and Concerns 1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process. 2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years. 3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors? Teaching Tips 1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home. 2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation. 3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species. 4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: www.inhs.uiuc.edu/cbd/herpdist/species/am_platine.html. 5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

Punctuated model Time Graduated model Figure 14.10 Figure 14.10 Two models for the tempo of evolution Figure 14.10

THE EVOLUTION OF BIOLOGICAL NOVELTY What accounts for the evolution of biological novelty? Student Misconceptions and Concerns 1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders. 2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity. Teaching Tips 1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House! 2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.

Adaptation of Old Structures for New Functions Birds: Are derived from a lineage of earthbound reptiles Evolved flight from flightless ancestors Student Misconceptions and Concerns 1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders. 2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity. Teaching Tips 1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House! 2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.

Artist’s reconstruction Wing claw (like reptile) Teeth (like reptile) Feathers Figure 14.11 An extinct bird: Archaeopteryx Long tail with many vertebrae (like reptile) Fossil Artist’s reconstruction Figure 14.11

Exaptations can account for the gradual evolution of novel structures. An exaptation: Is a structure that evolves in one context, but becomes adapted for another function Is a type of evolutionary remodeling Exaptations can account for the gradual evolution of novel structures. Student Misconceptions and Concerns 1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders. 2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity. Teaching Tips 1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House! 2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.

Bird wings are modified forelimbs that were previously adapted for non-flight functions, such as: Thermal regulation Courtship displays Camouflage The first flights may have been only glides or extended hops as the animal pursued prey or fled from a predator. Student Misconceptions and Concerns 1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders. 2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity. Teaching Tips 1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House! 2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.

Evo-Devo: Development and Evolutionary Novelty A subtle change in a species’ developmental program can have profound effects, changing the: Rate Timing Spatial pattern of development Student Misconceptions and Concerns 1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders. 2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity. Teaching Tips 1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House! 2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context. © 2010 Pearson Education, Inc.

Evo-devo, evolutionary developmental biology, is the study of the evolution of developmental processes in multicellular organisms. Student Misconceptions and Concerns 1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders. 2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity. Teaching Tips 1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House! 2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.

Animation: Allometric Growth Paedomorphosis: Is the retention into adulthood of features that were solely juvenile in ancestral species Has occurred in the evolution of Axolotl salamanders Humans Student Misconceptions and Concerns 1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders. 2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity. Teaching Tips 1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House! 2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context. Animation: Allometric Growth

Gills Figure 14.12 Paedomorphosis Figure 14.12

(paedomorphic features) Chimpanzee fetus Chimpanzee adult Figure 14.13 Comparison of human and chimpanzee skull development Human fetus Human adult (paedomorphic features) Figure 14.13

Homeotic genes are master control genes that regulate: When structures develop How structures develop Where structures develop Mutations in homeotic genes can profoundly affect body form. Student Misconceptions and Concerns 1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders. 2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity. Teaching Tips 1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House! 2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.

EARTH HISTORY AND MACROEVOLUTION Macroevolution is closely tied to the history of the Earth. Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

Geologic Time and the Fossil Record The fossil record is: The sequence in which fossils appear in rock strata An archive of macroevolution Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

Figure 14.14 A gallery of fossils

Figure 14.14a Petrified wood

Figure 14.14b Insect fossil in amber

Figure 14.14c Dinosaur bone Figure 14.14c

Figure 14.14d Dinosaur footprints

Figure 14.14e Mammoth tusks Figure 14.14e

Animation: The Geologic Record Animation: Macroevolution Geologists have established a geologic time scale reflecting a consistent sequence of geologic periods. Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth. Animation: The Geologic Record Animation: Macroevolution

Table 14.1 The Geologic Time Scale

Table 14.1a Precambrian Table 14.1a

Table 14.1b Paleozoic era Table 14.1b

Table 14.1c Mesozoic era Table 14.1c

Table 14.1d Cenozoic era Table 14.1d

Fossils are reliable chronological records only if we can determine their ages, using: The relative age of fossils, revealing the sequence in which groups of species evolved, or The absolute age of fossils, requiring other methods such as radiometric dating Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

Radiometric dating: Is the most common method for dating fossils Is based on the decay of radioactive isotopes Helped establish the geologic time scale Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

(as % of living organism’s Carbon-14 radioactivity Radioactive decay of carbon-14 100 75 (as % of living organism’s Carbon-14 radioactivity C-14 to C-12 ratio) 50 25 5.6 11.2 16.8 22.4 28.0 33.6 39.2 44.8 50.4 Time (thousands of years) How carbon-14 dating is used to determine the vintage of a fossilized clam shell Carbon-14 in shell Figure 14.15 Radiometric dating Figure 14.15

Plate Tectonics and Macroevolution The continents are not locked in place. Continents drift about the Earth’s surface on plates of crust floating on a flexible layer called the mantle. The San Andreas fault is: In California At a border where two plates slide past each other Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

Figure 14.16 California's San Andreas fault

About 250 million years ago: Plate movements formed the supercontinent Pangaea The total amount of shoreline was reduced Sea levels dropped The dry continental interior increased in size Many extinctions occurred Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

Figure 14.17 Present Cenozoic 65 135 Mesozoic 251 million years ago North America Eurasia 65 Africa South America India Madagascar Australia Antarctica Laurasia 135 Mesozoic Gondwana Figure 14.17 The history of plate tectonics 251 million years ago Pangaea Paleozoic Figure 14.17

About 180 million years ago: Pangaea began to break up Large continents drifted increasingly apart Climates changed The organisms of the different biogeographic realms diverged Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

Plate tectonics explains: Why Mesozoic reptiles in Ghana (West Africa) and Brazil look so similar How marsupials were free to evolve in isolation in Australia Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

Mass Extinctions and Explosive Diversifications of Life The fossil record reveals that five mass extinctions have occurred over the last 600 million years. The Permian mass extinction: Occurred at about the time the merging continents formed Pangaea (250 million years ago) Claimed about 96% of marine species Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth. © 2010 Pearson Education, Inc.

The Cretaceous extinction: Occurred at the end of the Cretaceous period, about 65 million years ago Included the extinction of all the dinosaurs except birds Permitted the rise of mammals Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

The Process of Science: Did a Meteor Kill the Dinosaurs? Observation: About 65 million years ago, the fossil record shows that: The climate cooled Seas were receding Many plant species died out Dinosaurs (except birds) became extinct A thin layer of clay rich in iridium was deposited Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth. © 2010 Pearson Education, Inc.

Question: Is the iridium layer the result of fallout from a huge cloud of dust that billowed into the atmosphere when a large meteor or asteroid hit Earth? Hypothesis: The mass extinction 65 million years ago was caused by the impact of an extraterrestrial object. Prediction: A huge impact crater of the right age should be found somewhere on Earth’s surface. Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

Results: Near the Yucatán Peninsula, a huge impact crater was found that: Dated from the predicted time Was about the right size Was capable of creating a cloud that could have blocked enough sunlight to change the Earth’s climate for months Student Misconceptions and Concerns 1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x 365.25 = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day). 2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error. Teaching Tips 1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed. 2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations. 3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

Figure 14.18 Trauma for planet Earth and its Cretaceous life (Step 1)

Figure 14.18 Trauma for planet Earth and its Cretaceous life (Step 2)

Chicxulub crater Figure 14.18-3 Figure 14.18 Trauma for planet Earth and its Cretaceous life (Step 3) Figure 14.18-3

CLASSIFYING THE DIVERSITY OF LIFE Systematics focuses on: Classifying organisms Determining their evolutionary relationships Taxonomy is the: Identification of species Naming of species Classification of species Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Some Basics of Taxonomy Scientific names ease communication by: Unambiguously identifying organisms Making it easier to recognize the discovery of a new species Carolus Linnaeus (1707–1778) proposed the current taxonomic system based upon: A two-part name for each species (binomial nomenclature) A hierarchical classification of species into broader groups of organisms Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Naming Species Each species is assigned a two-part name or binomial, consisting of: The genus A name unique for each species The scientific name for humans is Homo sapiens, a two part name, italicized and latinized, and with the first letter of the genus capitalized. Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Hierarchical Classification Species that are closely related are placed into the same genus. Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Figure 14.19 Leopard (Panthera pardus) Tiger (Panthera tigris) Lion (Panthera leo) Figure 14.19 The four species within the genus Panthera Jaguar (Panthera onca) Figure 14.19

The taxonomic hierarchy extends to progressively broader categories of classification, from genus to: Family Order Class Phylum Kingdom Domain Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Figure 14.20 Species Panthera pardus Genus Panthera Leopard Family Felidae Order Carnivora Class Mammalia Figure 14.20 Hierarchical classification Phylum Chordata Kingdom Animalia Domain Eukarya Figure 14.20

Classification and Phylogeny The goal of systematics is to reflect evolutionary relationships. Biologists use phylogenetic trees to: Depict hypotheses about the evolutionary history of species Reflect the hierarchical classification of groups nested within more inclusive groups Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Order Family Genus Species Panthera pardus (leopard) Felidae Panthera Mephitis mephitis (striped skunk) Mephitis Carnivora Mustelidae Lutra lutra (European otter) Lutra Figure 14.21 The relationship of classification and phylogeny for some members of the order Carnivora Canis latrans (coyote) Canidae Canis Canis lupus (wolf) Figure 14.21

Sorting Homology from Analogy Homologous structures: Reflect variations of a common ancestral plan Are the best sources of information used to Develop phylogenetic trees Classify organisms according to their evolutionary history Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Convergent evolution: Involves superficially similar structures in unrelated organisms Is based on natural selection Similarity due to convergence: Is called analogy, not homology Can obscure homologies Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Molecular Biology as a Tool in Systematics Molecular systematics: Compares DNA and amino acid sequences between organisms Can reveal evolutionary relationships Some fossils are preserved in such a way that DNA fragments can be extracted for comparison with living organisms. Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Figure 14.22 Studying ancient DNA

The Cladistic Revolution Cladistics is the scientific search for clades. A clade: Consists of an ancestral species and all its descendants Forms a distinct branch in the tree of life Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Iguana Outgroup (reptile) Duck-billed platypus Ingroup Hair, mammary Kangaroo Ingroup (mammals) Hair, mammary glands Figure 14.23 A simplified example of cladistics Gestation Beaver Long gestation Figure 14.23

Cladistics has changed the traditional classification of some organisms, including the relationships between: Dinosaurs Birds Crocodiles Lizards Snakes Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Lizards and snakes Crocodilians Pterosaurs Common ancestor of dinosaurs, and birds Ornithischian dinosaurs Figure 14.24 How cladistics is shaking phylogenetic trees Saurischian dinosaurs Birds Figure 14.24

Classification: A Work in Progress Linnaeus: Divided all known forms of life between the plant and animal kingdoms Prevailed with his two-kingdom system for over 200 years In the mid-1900s, the two-kingdom system was replaced by a five-kingdom system that: Placed all prokaryotes in one kingdom Divided the eukaryotes among four other kingdoms Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Animation: Classification Schemes In the late 20th century, molecular studies and cladistics led to the development of a three-domain system, recognizing: Two domains of prokaryotes (Bacteria and Archaea) One domain of eukaryotes (Eukarya) Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems. Animation: Classification Schemes

Domain Bacteria Earliest Domain Archaea organisms The protists (multiple kingdoms) Kingdom Plantae Domain Eukarya Figure 14.25 The three-domain classification system Kingdom Fungi Kingdom Animalia Figure 14.25

Evolution Connection: Rise of the Mammals Mass extinctions: Have repeatedly occurred throughout Earth’s history Were followed by a period of great evolutionary change Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems. © 2010 Pearson Education, Inc.

Fossil evidence indicates that: Mammals first appeared about 180 million years ago The number of mammalian species Remained steady and low in number until about 65 million years ago and then Greatly increased after most of the dinosaurs became extinct Student Misconceptions and Concerns 1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer. 2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names! 3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups. Teaching Tips 1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household. 2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity. 3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect. 4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

Figure 14.26 Ancestral mammal Monotremes (5 species) Reptilian Extinction of dinosaurs Reptilian ancestor Marsupials (324 species) Eutherians (5,010 species) Figure 14.26 The increase in mammalian diversity after the extinction of dinosaurs 250 200 150 100 65 50 American black bear Millions of years ago Figure 14.26

Bacteria Earliest organisms Archaea Eukarya Figure 14.UN3 Figure 14.UN3 Summary: domains Eukarya Figure 14.UN3