Chapter 21

1. Objectives: Complete activity on reading from last night. Evolution Game finally??? Notes on Evolution HW: Flashcards 21-40 – Quiz Tmo. Chapter 21 The Evidence for Evolution

2. Evolution Natural Selection can Produce Evolution Fossil Record Direct Evidence! Embryology Molecular Biology Anatomy Biogeography

3. Fossil Record • Shows change has occurred. • Detailed information on course of evolution through time.

4. How to Create a Fossil • Organism must immediately be buried in sediment. • Calcium in hard tissue and bone must mineralize. • Surrounding sediment must harden to rock. Only a fraction of extinct animals known from fossils because they may be inaccessible, destroyed or may not fossilize.

5. Article on dino fossils

6. Fossil Dating • Date the rocks where fossils occur. • Relative Dating (umm ew) • Deeper rocks = older • More accurate if you know the erosion rate of sedimentary rock and find a relative age. • Absolute Dating – radioactive isotopes decay at constant rate. Can express date in millions of years. When arranged oldest to youngest you can se progression of life through time. See worksheet on radioactive dating

7. Simple Evidence • Genus: Hyracotherium (horse)

8. Fossils • Clear record of major evo transition through time. • There are gaps that paleontologists are continually trying to fill. • Why are there gaps? • Fossils found to link all major vertebrate groups. • Land hoofed orgs  whales and dolphins • Lizards  snakes • Curved oysters  rounded oysters • Archaeopteryx – transition between birds and dinosaurs. • Shows strongest evidence that evo has occurred.

9. Not always simple • Horse evidence simple. • Evo is NOT uniform/constant over time. Rates vary and non-uniform branches exist. Not going toward “perfect”

10. Natural Selection • Most agree that this is responsible for evolutionary change. • Modern day evidence confirms through • Field research • Lab • Natural selection • Human altered

11. Since D’s Finches • More finch testing has been conducted to prove adaptive radiation of finches is genetic, not environmental.

12. Modern Day Evolution • Bistonbetularia = peppered moth in 19th Century. • Industrial Melanism Rule

13. Moth activity/bunny demo/mark and recapture

14. Artificial Selection Mimics Natural Selection • Favors phenotypes and if they are genetic – allowed to pass on and lead to evo change. Strong proof that selection is an effective evo. Process. • Traits WE have selected for • Fruit fly body size, eye color, growth rate, lifespan, exploratory behavior. • Cattle • Pigs • Strawberries – much different today • Corn – selected for oil content in 1986. 10yrs later inc. of 450%

15. Unintentional Selection • Breeding for specific traits may allow other traits to come forward • Foxes – genes for docile had other effects (pleiotropy) • Floppy ears, curled tails, etc. • Because Art.Sel has worked, most scientists believe Nat.Sel caused evo in fossil record. • Some changes may seem minor (fruitflies) but look at others (dog breeds) to see massive evo. Change.

16. Fox Article

17. Evidence • Homology – same bones put to different uses. Forelimbs of vertebrates are homologous. Different appearances and functions but common ancestor. • Embryology – embryos exhibit characteristics of early ancestors. As if new instructions are layered on old ones. • Gill slits • Long bony tail • Fine fur (Lanugo)

18. Evidence • Vestigial Structures – no apparent function for structure but resembles structure presumed ancestors had. • Wiggling ears • Tail • Appendix • Wisdom teeth • Hip bones in snakes • Finger nails on manatee flippers.

19. Evidence • Molecular Record – when ancestors give rise to 2+ descendents the descendents will initially have increased similarity in DNA. More closely related means more similar DNA. • When degree of genetic similarity is compared with fossil relationships = close match. • Human hemoglobin polypeptide compared with chimps, gorillas, orangutans, macaques. Fewer diff from humans in the 146 aa chain than dogs and distantly related mammals. • Non mammals are more different and non vertebrates are most different. • DNA codes for physical appearance so it makes sense that DNA is similar in similar appearing organisms. • Junk (non-coding DNA) is similar too = direct evidence for evolution.

20. Objectives • Quiz on 21-40 • Open Ended Question on Evolution • Complete Evolution Notes • Review Important Flashcard Information. H.W. www.Khanacademy.org Hardy-weinberg principle Watch and take notes. WILL be on AP test!

21. Types of Evolution • Convergent evolution – same forms, different lineage. • Divergent evo – two organisms don’t resemble each other anymore but began with a similar ancestor. Clearly related but different features. • Tortoise went moist dome shell vs. dry saddle shell • Finch beak types x13! • Divergent because different in only a few traits and similar in so many. • Parallel Evo – when different organisms are placed under similar env. Pressures and adapt similarly. • Homologous is most like… • Analogous is most like… • Australia split 50 mya after marsupials but before placentals but they resemble placentals because of similar selective pressures in similar env.

22. Critics of Darwin • Evolution is just a theory… • Fossils jump – no intermediates • Complex structures are too complex for random processes • Evo violates the second law of thermodynamics “things become more disorganized due to random events, not more organized” • Proteins are too improbable. • Natural selection doesn’t imply evo. • Irreducible complexity argument.