Darwin & Theory of Evolution by Natural Selection

1. Darwin & Theory of Evolution by Natural Selection Chapter 22

2. Evolution- Just a Theory? • Theory vs. Law vs. Dogma

3. Theory – explain • Laws describe • Dogma is not tested – beliefs • Science is limited to things we can measure, test. • Hypothesis – is an “educated” guess to explain a problem,

4. Scientific Method • Problem, observation • Background information, literature search • Hypothesis based on previous work • Experiment to test hypothesis • Analyze results • If hypothesis supported – publish a paper.

5. Darwin’s Theory • Populations have inherent variation among individuals. • These traits are heritable • Resources in the environment are limited • Populations have a greater fertility than their environment can sustain. • Populations would grow exponentially, but most remain stable in size.

6. A population of Liguus fascitus Variation in shell coloration patterns

7. Fig. 22-10

8. Darwin’s Theory continued: • There is a struggle to survive among the offspring called Natural Selection. • The survivors are better fit • Fitness is the ability to have more offspring (frequency of genes in the genepool).

9. Natural Selection • “struggle “ or competition does not have to be a fight to death • may just be as simple as a seed germinating earlier and getting established first. It produces 120 seeds. A later germinating plant makes only 50 seeds. • “Fitness” is the success rate of the offspring in future generations.

10. Fig. 22-7

11. Branch point (common ancestor) Lungfishes Amphibians 1 Fig. 22-19 Tetrapods Mammals 2 Tetrapod limbs Amniotes Lizards and snakes 3 Amnion 4 Crocodiles Homologous characteristic 5 Ostriches Birds 6 Feathers Hawks and other birds

12. Some Evidence for Evolution • Microevolution- antibiotic, pesticide resistance • Artificial selection • Fossil record • Biochemical comparisons • Protein sequences • DNA, gene comparisons • Morphological comparisons • Embryology • Biogeography • Genetically modified organisms

13. Fig. CO 13

15. All made by Artificial Selection from wild mustard Artificial Selection: human designed breeding of plants and animals for desired traits by selecting which individuals get to reproduce.

16. Terminal bud Lateral buds Cabbage Brussels sprouts Flower clusters Fig. 22-9 Leaves Kale Cauliflower Stem Wild mustard Flowers and stems Broccoli Kohlrabi

17. Fig. 25-18 Close North American relative, the tarweed Carlquistia muirii 1.3 million years MOLOKAI KAUAI 5.1 million years Dubautia laxa MAUI OAHU 3.7 million years Argyroxiphiumsandwicense LANAI HAWAII 0.4 million years Dubautia waialealae Dubautia scabra Dubautia linearis

18. Fossils • Give us real dates • Show us what the “intermediate” features looked like • “Missing Links” the intermediate species along lineages • e.g.. From apes to humans • Very limited, chances of a species getting fossilized are low.

19. Layers of deposited sediment Fig. 22-3 Younger stratum with more recent fossils Older stratum with older fossils

23. Missing Links

24. (a) Pakicetus (terrestrial) Fig. 22-16 (b) Rhodocetus (predominantly aquatic) Pelvis and hind limb (c) Dorudon (fully aquatic) Pelvis and hind limb (d) Balaena (recent whale ancestor)

25. Fig. 13.4

26. Hyracoidea (Hyraxes) Sirenia (Manatees and relatives) Moeritherium Barytherium Fig. 22-8 Deinotherium Mammut Platybelodon Stegodon Mammuthus Elephas maximus (Asia) Loxodonta africana (Africa) Loxodonta cyclotis (Africa) 34 5.5 104 0 24 2 Millions of years ago Years ago

27. Platybelodon Stegodon Fig. 22-8a Mammuthus Elephas maximus (Asia) Loxodonta africana (Africa) Loxodonta cyclotis (Africa) 0 24 5.5 2 104 34 Years ago Millions of years ago

28. Fig. 13.3

29. 0 2 Fossil Evidence of Evolution in a group of Trilobites over time Location and angle of head spines 4 4 Bristolia insolens 6 4 8 Bristolia bristolensis 3 Fig. 22-15 10 12 Depth (meters) 3 Bristolia harringtoni 2 14 16 Bristolia mohavensis 18 1 3 2 Latham Shale dig site, San Bernardino County, California 1

30. 0 2 Fig. 22-15c 4 4 6 Bristolia insolens 4 Depth (meters) 8 Bristolia bristolensis 3 10 3

31. Vestigial Structures • Come from an ancestral species • No longer serve an function • Are neutral traits, not harmful, and thus not “selected against” in origins of new species • Appendix • Hip bones in Pythons, Whales • Ear muscles in humans

32. backbone pelvic girdle coccyx (bones where many other mammals have a tail) thighbone attached to pelvic girdle small bone attached to pelvic girdle

33. Molecular Comparisons • Counts mutations to an important gene • “Conserved” genes mutate slowly, used to show distant relationships • Can compare any living species, or fossil tissues that still have DNA • Show how closely they are related • Doesn’t show what intermediate species looked like

34. Fig. 13.5

36. Molecular clocks • Useful comparisons of any living species • Uses date from fossil for when species lineages separated • Compares mutations to common gene between these species to show a rate of mutation in a gene • Can make an estimate for species with that gene, that do not have a fossil record • Gives an estimated date

37. Fig. 13.6

38. Embryology • Animals only, especially the vertebrates • The more closely related two species are the more similar their embryo will be for a longer period of development

39. Fig. 22-18 Pharyngeal pouches Post-anal tail Chick embryo (LM) Human embryo

40. Comparative embryology

41. Comparative embryology

42. Structures • Homologous structures- • Show common ancestry • Derived from a common ancestral structure • May have specialized into different functions

43. Homologous Bones in Mammals

44. Humerus Fig. 22-17 Radius Ulna Carpals Metacarpals Phalanges Human Whale Bat Cat

46. Analogous Features • Have same functions ( by convergence) • Do not have a common ancestry • Are not derived from the same ancestral feature

47. Butterfly and Bird • No bones in butterfly, not from common ancestor • Structures not related

48. Convergence • Not closely related • Look similar due to adapting to similar habitat

50. Fig. 13.9b