Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Lectures by Chris C. Romero PowerPoint ® Lectures for Essential Biology, Third Edition – Neil Campbell, Jane Reece, and Eric Simon Essential Biology with Physiology, Second Edition – Neil Campbell, Jane Reece, and Eric Simon CHAPTER 14 How Biological Diversity Evolves

Biology and Society: One Troublesome Species or Two? Mosquitoes have assumed a more serious role in public health since the outbreak of West Nile virus. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

Figure 14.1

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings All mosquitoes look roughly alike. –But close examination reveals many distinct species, two of which may bite birds or people. DNA comparisons between North American and European species –Have revealed mosquito hybrids in North America that bite both birds and people and are more likely to spread West Nile virus.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Macroevolution and the Diversity of Life Macroevolution –Encompasses the major biological changes evident in the fossil record. –Includes the formation of new species.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Speciation –Is the focal point of macroevolution. –May occur based on two contrasting patterns.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings In nonbranching evolution, a population transforms but does not create a new species.

Figure 14.2a

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings In branching evolution, one or more new species branch from a parent species that may continue to exist.

Figure 14.2b The biological species concept defines a species as –A population or group of populations whose members have the potential to interbreed and produce fertile offspring.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Origin of Species Species is a Latin word meaning “kind” or “appearance.”

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings What Is a Species? Galápagos Tortoise Galápagos Sea Lion

Figure 14.3

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The biological species concept cannot be applied in all situations, for example, with fossils and asexual organisms.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Reproductive Barriers between Species Prezygotic barriers prevent mating between species.

Figure 14.4

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Prezygotic barriers include –Temporal isolation. –Habitat isolation. –Mechanical isolation. –Gametic isolation. Blue-Footed Boobies Courtship Ritual Giraffe Courtship Ritual Albatross Courtship Ritual

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Behavioral isolation

Figure 14.5

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Postzygotic barriers –Are mechanisms that operate should interspecies mating actually occur and form hybrid zygotes.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Postzygotic barriers include –Hybrid inviability. –Hybrid sterility.

Figure 14.6

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Mechanisms of Speciation A key event in the potential origin of a species occurs when a population is somehow severed from other populations of the parent species.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The two modes of speciation are –Allopatric speciation. –Sympatric speciation.

Figure 14.7

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Allopatric Speciation Geologic processes –Can fragment a population into two or more isolated populations. –Can contribute to allopatric speciation. Galápagos Marine Iguana Grand Canyon Galápagos Islands Overview

Figure 14.8

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Speciation occurs only with the evolution of reproductive barriers between the isolated population and its parent population.

Figure 14.9

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Sympatric Speciation Sympatric speciation occurs if a genetic change produces a reproductive barrier between mutants and the parent population. –Polyploidy, a mechanism of sympatric speciation, was first observed by Hugo de Vries.

Figure 14.10

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Polyploids –Can originate from accidents during cell division. –Can result from the hybridization of two parent species. Many domesticated plants are the result of sympatric speciation.

Figure 14.11

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings What Is the Tempo of Speciation? Traditional evolutionary trees diagram the descent of species as gradual divergence.

Figure 14.12a

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Punctuated equilibrium –Is a contrasting model of evolution. –States that species most often diverge in spurts of relatively sudden change. –Accounts for the relative rarity of transitional fossils.

Figure 14.12b

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Evolution of Biological Novelty What accounts for the evolution of biological novelty?

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Adaptation of Old Structures for New Functions Birds –Are derived from a lineage of earthbound reptiles. –Developed from flightless ancestors, but how?

Figure 14.13

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Exaptation –Involves a structure that evolves in one context gradually becoming adapted for other functions. –Is a mechanism for novel features to arise gradually through a series of intermediate stages.

“Evo-Devo”: Development and Evolutionary Novelty A subtle change in developmental genes can have profound effects. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

Paedomorphosis –Is the retention of juvenile body features in the adult. –Is important in human evolution.

Figure 14.14

Figure 14.15

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Earth History and Macroevolution Macroevolution –Is closely tied to the history of the Earth.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Geologic Time and the Fossil Record The fossil record –Is an archive of macroevolution.

Figure 14.16

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Geologists have established a geologic time scale reflecting a consistent sequence of geologic periods. Macroevolution The Geologic Record

Table 14.1

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Radiometric dating –Is the most common method for dating fossils. –Has helped establish the geologic time scale.

Figure 14.17a

Figure 14.17b

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Plate Tectonics and Macroevolution The continents are not locked in place. –They drift about Earth’s surface on plates of crust floating on a flexible layer called the mantle. California’s infamous San Andreas fault –Is at a border where two plates slide past each other.

Figure 14.18

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings About 250 million years ago –Plate movements formed the supercontinent Pangaea. –Many extinctions occurred, allowing survivors to diversify. Volcanic Eruption Lava Flow

Figure 14.19

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings About 180 million years ago –Pangaea began to break up, causing geographic isolation.

Mass Extinctions and Explosive Diversifications of Life The fossil record reveals an episodic history, –With long, relatively stable periods punctuated by briefer intervals when the turnover in species composition was much more extensive. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

Extinction is inevitable in a changing world and occurs all the time. –However, extinction rates have not been steady. Extinctions typically eliminate various species of organisms –And are followed by explosive diversifications of organisms.

The Process of Science: Did a Meteor Kill the Dinosaurs? Scientists believe that about 65 million years ago, at the end of the Cretaceous period, –A meteor impact contributed to the extinction of the dinosaurs. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

Figure 14.20

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Classifying the Diversity of Life Systematics –Is the study of the diversity and relationships of organisms, both past and present. Taxonomy –Is the identification, naming, and classification of species.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Some Basics of Taxonomy Carolus Linnaeus –Developed the formal naming system used today.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Naming Species Each species is assigned a two-part name or binomial, consisting of the genus and the species.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Hierarchical Classification The taxonomic hierarchy

Figure 14.21

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Classification and Phylogeny The goal of classification is to reflect phylogeny, the evolutionary history of a species.

Figure 14.22

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Sorting Homology from Analogy Homologous structures –Are one of the best sources of information about phylogenetic relationships.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Convergent evolution –Involves superficially similar structures in unrelated organisms based on natural selection. Analogy –Is similarity due to convergence.

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Molecular Biology as a Tool in Systematics Molecular systematics –Compares DNA and amino acid sequences between organisms. –Can reveal evolutionary relationships.

Figure 14.23

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Cladistic Revolution Cladistics –Is the scientific search for clades, distinctive branches in the history of life.

Figure 14.24

Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Cladistics –Has changed traditional classification of some organisms.

Figure 14.25

Arranging Life into Kingdoms: A Work in Progress Linnaeus designed a two-kingdom system of classification, –Which was replaced by a five-kingdom system in the mid-20th century. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

In the late 20th century, –Molecular studies and cladistics led to the development of a three-domain system. Classification Schemes

Figure 14.26

Evolution Connection: Just a Theory? Certain groups use the idea that evolution is “just a theory” –To discredit its validity and eliminate it from the science curricula in our public schools. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

The “just a theory” argument has two flaws: –It fails to separate Darwin’s two main ideas. –The term theory has a very different meaning in science than in general use.