1. © 2010 Pearson Education, Inc. Lectures by Chris C. Romero, updated by Edward J. Zalisko PowerPoint ® Lectures for Campbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean Dickey Campbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey Chapter 14 How Biological Diversity Evolves

2. 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.

3. Figure 14.00

4. © 2010 Pearson Education, Inc. 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

5. © 2010 Pearson Education, Inc. MACROEVOLUTION AND THE DIVERSITY OF LIFE Macroevolution: –Encompasses the major biological changes evident in the fossil record –Includes the formation of new species

6. © 2010 Pearson Education, Inc. Speciation: –Is the focal point of macroevolution –May occur based on two contrasting patterns

7. © 2010 Pearson Education, Inc. In nonbranching evolution: –A population transforms but –Does not create a new species

8. Branching Evolution (results in speciation) Nonbranching Evolution (no new species) PATTERNS OF EVOLUTION Figure 14.1

9. © 2010 Pearson Education, Inc. 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

10. © 2010 Pearson Education, Inc. THE ORIGIN OF SPECIES Species is a Latin word meaning: –“Kind” or –“Appearance.”

11. © 2010 Pearson Education, Inc. 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”

12. Similarity between different species Figure 14.2a

13. Diversity within one species Figure 14.2b

14. © 2010 Pearson Education, Inc. The biological species concept cannot be applied in all situations, including: –Fossils –Asexual organisms

15. © 2010 Pearson Education, Inc. Reproductive Barriers between Species Prezygotic barriers prevent mating or fertilization between species.

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

17. © 2010 Pearson Education, Inc. Prezygotic barriers include: –Temporal isolation –Habitat isolation –Behavioral isolation –Mechanical isolation –Gametic isolation

18. Temporal Isolation Skunk species that mate at different times Figure 14.4a

19. Habitat Isolation Garter snake species from different habitats Figure 14.4b

20. Mating ritual of blue-footed boobies Behavioral Isolation Figure 14.4c

21. Mechanical Isolation Snail species whose genital openings cannot align Figure 14.4d

22. Sea urchin species whose gametes cannot fuse Gametic Isolation Figure 14.4e

23. © 2010 Pearson Education, Inc. Postzygotic barriers operate if: –Interspecies mating occurs and –Hybrid zygotes form

24. © 2010 Pearson Education, Inc. Postzygotic barriers include: –Reduced hybrid viability –Reduced hybrid fertility –Hybrid breakdown

25. Frail hybrid salamander offspring Reduced Hybrid Viability Figure 14.5a

26. Reduced Hybrid Fertility Mule (sterile hybrid of horse and donkey) Donkey Mule Horse Figure 14.5b

27. Hybrid Breakdown Sterile next-generation rice hybrid Figure 14.5c

28. © 2010 Pearson Education, Inc. 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.

29. © 2010 Pearson Education, Inc. Species can form by: –Allopatric speciation, due to geographic isolation –Sympatric speciation, without geographic isolation

30. Allopatric speciation Simpatric speciation Figure 14.6

31. © 2010 Pearson Education, Inc. Allopatric Speciation Geologic processes can: –Fragment a population into two or more isolated populations –Contribute to allopatric speciation

32. Ammospermophilus harrisii Ammospermophilus leucurus Figure 14.7

33. © 2010 Pearson Education, Inc. Speciation occurs only with the evolution of reproductive barriers between the isolated population and its parent population.

34. Geographic barrier Populations interbreed Time Populations become allopatric Populations become sympatric Populations cannot interbreed Reproductive isolation: Speciation has occurred Gene pools merge: No speciation Figure 14.8

35. © 2010 Pearson Education, Inc. 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

36. © 2010 Pearson Education, Inc. Polyploids can: –Originate from accidents during cell division –Result from the hybridization of two parent species

37. © 2010 Pearson Education, Inc. Many domesticated plants are the result of sympatric speciation, including: –Oats –Potatoes –Bananas –Peanuts –Apples –Coffee –Wheat

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

39. Figure 14.9a

40. © 2010 Pearson Education, Inc. 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

41. Punctuated model Graduated model Time Figure 14.10

42. © 2010 Pearson Education, Inc. THE EVOLUTION OF BIOLOGICAL NOVELTY What accounts for the evolution of biological novelty?

43. © 2010 Pearson Education, Inc. Adaptation of Old Structures for New Functions Birds: –Are derived from a lineage of earthbound reptiles –Evolved flight from flightless ancestors

44. Wing claw (like reptile) Teeth (like reptile) Long tail with many vertebrae (like reptile) Feathers Fossil Artist’s reconstruction Figure 14.11

45. © 2010 Pearson Education, Inc. 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.

46. © 2010 Pearson Education, Inc. 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.

47. 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 © 2010 Pearson Education, Inc.

48. Evo-devo, evolutionary developmental biology, is the study of the evolution of developmental processes in multicellular organisms.

49. © 2010 Pearson Education, Inc. Paedomorphosis: –Is the retention into adulthood of features that were solely juvenile in ancestral species –Has occurred in the evolution of –Axolotl salamanders –Humans

50. Gills Figure 14.12

51. Chimpanzee fetus Chimpanzee adult Human adult (paedomorphic features) Human fetus Figure 14.13

52. © 2010 Pearson Education, Inc. 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.

53. © 2010 Pearson Education, Inc. EARTH HISTORY AND MACROEVOLUTION Macroevolution is closely tied to the history of the Earth.

54. © 2010 Pearson Education, Inc. Geologic Time and the Fossil Record The fossil record is: –The sequence in which fossils appear in rock strata –An archive of macroevolution

55. Figure 14.14a

56. Figure 14.14b

57. Figure 14.14c

58. Figure 14.14d

59. Figure 14.14e

60. © 2010 Pearson Education, Inc. Geologists have established a geologic time scale reflecting a consistent sequence of geologic periods.

61. Table 14.1

62. Table 14.1a

63. Table 14.1b

64. Table 14.1c

65. Table 14.1d

66. © 2010 Pearson Education, Inc. 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

67. © 2010 Pearson Education, Inc. Radiometric dating: –Is the most common method for dating fossils –Is based on the decay of radioactive isotopes –Helped establish the geologic time scale

68. Carbon-14 in shell Time (thousands of years) Radioactive decay of carbon-14 How carbon-14 dating is used to determine the vintage of a fossilized clam shell Carbon-14 radioactivity (as % of living organism’s C-14 to C-12 ratio) 100 75 0 50 25 0 5.6 50.4 11.216.8 22.4 28.0 33.6 39.244.8 Figure 14.15

69. © 2010 Pearson Education, Inc. 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

70. Figure 14.16

71. © 2010 Pearson Education, Inc. 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

72. Pangaea Present Paleozoic Cenozoic Mesozoic 251 million years ago 135 65 Laurasia Gondwana Eurasia India Madagascar North America Africa South America Antarctica Australia Figure 14.17

73. © 2010 Pearson Education, Inc. 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

74. © 2010 Pearson Education, Inc. 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

75. 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 © 2010 Pearson Education, Inc.

76. 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

77. 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 © 2010 Pearson Education, Inc.

78. 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.

79. © 2010 Pearson Education, Inc. 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

80. Chicxulub crater Figure 14.18-3

81. © 2010 Pearson Education, Inc. 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

82. © 2010 Pearson Education, Inc. 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 –A hierarchical classification of species into broader groups of organisms

83. © 2010 Pearson Education, Inc. 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.

84. © 2010 Pearson Education, Inc. Hierarchical Classification Species that are closely related are placed into the same genus.

85. Jaguar (Panthera onca) Lion (Panthera leo) Tiger (Panthera tigris) Leopard (Panthera pardus) Figure 14.19

86. © 2010 Pearson Education, Inc. The taxonomic hierarchy extends to progressively broader categories of classification, from genus to: –Family –Order –Class –Phylum –Kingdom –Domain

87. Leopard (Panthera pardus) Species Panthera pardus Genus Panthera Family Felidae Order Carnivora Class Mammalia Phylum Chordata Kingdom Animalia Domain Eukarya Figure 14.20

88. © 2010 Pearson Education, Inc. 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

89. Panthera pardus (leopard) Species Genus Felidae Order Carnivora Family Canis Lutra Panthera Mephitis Canidae Mustelidae Canis lupus (wolf) Canis latrans (coyote) Lutra lutra (European otter) Mephitis mephitis (striped skunk) Figure 14.21

90. © 2010 Pearson Education, Inc. 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

91. © 2010 Pearson Education, Inc. 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

92. © 2010 Pearson Education, Inc. 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.

93. Figure 14.22

94. © 2010 Pearson Education, Inc. 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

95. Hair, mammary glands Long gestation Gestation Duck-billed platypus Iguana Outgroup (reptile) Ingroup (mammals) Beaver Kangaroo Figure 14.23

96. © 2010 Pearson Education, Inc. Cladistics has changed the traditional classification of some organisms, including the relationships between: –Dinosaurs –Birds –Crocodiles –Lizards –Snakes

97. Lizards and snakes Crocodilians Saurischian dinosaurs Ornithischian dinosaurs Pterosaurs Birds Common ancestor of crocodilians, dinosaurs, and birds Figure 14.24

98. © 2010 Pearson Education, Inc. 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

99. © 2010 Pearson Education, Inc. 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)

100. Kingdom Animalia Domain Archaea Earliest organisms Domain Bacteria Domain Eukarya Kingdom Fungi Kingdom Plantae The protists (multiple kingdoms) Figure 14.25

101. Evolution Connection: Rise of the Mammals Mass extinctions: –Have repeatedly occurred throughout Earth’s history –Were followed by a period of great evolutionary change © 2010 Pearson Education, Inc.

102. 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

103. American black bear Eutherians (5,010 species) Millions of years ago Monotremes (5 species) Marsupials (324 species) Ancestral mammal Reptilian ancestor Extinction of dinosaurs 250 200150100 50 65 0 Figure 14.26