CHAPTER 15 Tracing Evolutionary History

1. CHAPTER 15Tracing Evolutionary History Modules 15.6 – 15.14

2. 15.6 Key adaptations may enable species to proliferate after mass extinctions • Adaptations that have evolved in one environmental context may be able to perform new functions when conditions change • Example: Plant species with catch basins, an adaptation to dry environments Figure 15.6

3. 15.7 “Evo-devo:” Genes that control development play a major role in evolution • “Evo-devo” is a field that combines evolutionary and developmental biology • Major adaptations may arise rapidly if mutations occur in genes that control an organism’s early development

4. Paedomorphosis, the retention of juvenile characteristics in the adult, seems to have played a role in human evolution Chimpanzee fetus Chimpanzee adult Figure 15.7A, B Human fetus Human adult

5. Stephen Jay Gould argued that there was a connection between our juvenile physical traits and our long period of dependency • The youthful features of Mickey Mouse elicit affectionate, parental responses Figure 15.7C

6. 15.8 Evolutionary trends do not mean that evolution is directed toward a goal • Evolutionary trends may reflect unequal speciation or survival of species on a branching evolutionary tree

7. Figure 15.8

8. 15.9 Phylogenetic trees strive to represent evolutionary history • Phylogeny is the evolutionary history of a group of organisms

9. Cactusground finch Smalltree finch Mediumtree finch Woodpeckerfinch Mediumground finch Smallground finch Large cactusground finch Vegetarianfinch Largetree finch Mangrovefinch Greenwarbler finch Graywarbler finch Largeground finch Sharp-beakedground finch Budeaters Seedeaters Cactus flowereaters Insecteaters Ground finches Tree finches Warbler finches Common ancestor fromSouth America mainland Figure 15.9

10. SYSTEMATICS AND PHYLOGENETIC BIOLOGY 15.10 Systematists classify organisms by phylogeny • Reconstructing phylogeny is part of systematics • the study of biological diversity and classification • Taxonomists assign a two-part name to each species • The first name, the genus, covers a group of related species • The second name refers to a species within a genus

11. Genera are grouped into progressively larger categories Table 15.10

12. Taxonomists often debate the particular placement of organisms in categories as they strive to make their categories reflect evolutionary relationships

13. Feliscatus(domesticcat) Mephitismephitis(stripedskunk) Lutralutra(Europeanotter) Canisfamiliaris(domesticdog) Canislupus(wolf) SPECIES GENUS Felis Mephitis Lutra Canis FAMILY Felidae Mustelidae Canidae ORDER Carnivora Figure 15.10

14. 15.11 Homology indicates common ancestry, but analogy does not • Homologous structures are evidence that organisms have evolved from a common ancestor • In contrast, analogous similarities are evidence that organisms from different evolutionary lineages have undergone convergent evolution • Their resemblances have resulted from living in similar environments

15. Example: California ocotillo and allauidia of Madagascar Figure 15.11

16. 15.12 Molecular biology is a powerful tool in systematics • Systematists increasingly use molecular techniques to • classify organisms • develop phylogenetic hypotheses Human Chimpanzee Gorilla Orangutan Figure 15.12B

17. Polarbear Asiaticblack bear Americanblack bear Giantpanda Spectacledbear Brown bear Sunbear Slothbear Lesserpanda Raccoon • A phylogenetic tree based on molecular data Pleistocene Pliocene Miocene Ursidae Procyonidae Oligocene Common ancestralcarnivorans Figure 15.12A

18. 15.13 Systematists attempt to make classification consistent with phylogeny • Homologous features are used to compare organisms • Cladistic analysis attempts to define monophyletic taxa

19. TAXA Outgroup(Reptiles) Ingoup(Mammals) Eastern boxturtle Duck-billedplatypus Red kangaroo North Americanbeaver CHARACTERS Long gestation Gestation Hair, mammary glands Vertebral column Long gestation 3 Gestation 2 Hair, mammary glands 1 Vertebral column Figure 15.13A

20. Phylogenetic tree according to cladistic analysis • Cladistic analysis is often a search for the simplest hypotheses about phylogeny Lizards Snakes Crocodiles Birds • Phylogenetic tree according to classical systematics Lizards Snakes Crocodiles Birds Figure 15.13B, C

21. THE DOMAINS OF LIFE 15.14 Arranging life into kingdoms is a work in progress • For several decades, systematists have classified life into five kingdoms MONERA PROTISTA PLANTAE FUNGI ANIMALIA Earliestorganisms Figure 15.14A

22. The domain Bacteria • The domain Archaea • A third domain, the Eukarya, includes all kingdoms of eukaryotes • A newer system recognizes two basically distinctive groups of prokaryotes BACTERIA ARCHAEA EUKARYA Earliestorganisms Figure 15.14B