What do you notice?

1. What do you notice?

2. What do you notice?

3. What do you noticed?

4. What do you notice?

5. The Evidence for the Theory of Evolution

6. Fossil Evidence of Evolution • Fossils are the preserved remains of once-living organisms • Rock fossils are created when three events occur • organism buried in sediment • calcium in bone or other hard tissue mineralizes • surrounding sediment hardens to form rock

7. Fossil Evidence of Evolution • Absolute dating: age of fossils is estimated by rates of radioactive decay • Relative dating: position of the fossil in the sediment (oldest on bottom newer on top) • Isotopes, like U238, transform at precisely known rates into nonradioactive forms. • The rate of decay is known as an isotope’s half-life

8. Fossil Evidence of Evolution Radioactive Decay

9. Fossil Evidence of Evolution Fossil records document the course of life through time

10. Fossil Evidence of Evolution • Fossils document evolutionary transition • The oldest known bird fossil is the Archaeopteryx • It is intermediate between bird and dinosaur • Possesses some ancestral traits and some traits of present day birds • Archaeopteryx was first found in 1859

11. Fossil Evidence of Evolution Fossil of Archaeopteryx

12. Fossil Evidence of Evolution Recent discoveries • Four-legged aquatic mammal • Important link in the evolution of whales and dolphins from land-dwelling, hoofed ancestors • Fossil snake with legs • Tiktaalik: a species that bridged the gap between fish and the first amphibian • Oysters: small curved shells to large flat shells

13. Fossil Evidence of Evolution Whale “missing links”

14. Fossil Evidence of Evolution Evolutionary change in body size and toe reduction of horses

15. HOMOLOGOUS STRUCTURE • Similar features that originate in a shared ancestor (derive from same embryonic structure) • Can result from modifications that change an original feature to 2 extremely different types (wing and arm) Homologous structures

16. Anatomical Evidence for Evolution • Homologous structures: structures with different appearances and functions that all derived from the same body part in a common ancestor • structures with common evolutionary origins (can be similar in structure, function, or both) • The bones in the forelimb of mammals are homologous structures • Different functions, same ancestor structure

17. Anatomical Evidence for Evolution Homology of the bones of the forelimb of mammals

18. ANALAGOUS FEATURE Serve identical functions and look similar No anatomical/embryological similarity Wing developed independently and differently in more-recent ancestors of each animal Analogous structures: structures that do not have a common evolutionary origin but are similar in function Ex: wing of an insect, bat, bird and pterosaur

19. Vestigial structures of a whale: hind leg bones!? Anatomical Evidence for Evolution • Vestigial structures: have no apparent function, but resemble structures their ancestors possessed

20. Vestigial Structures Humans • Muscles for wiggling ears (similar muscles that animals use to move ears to hear predators or prey) • Tail bones present in human and all vertebrate embryos. In humans, the tail is reduced; most adults only have three to five tiny tail bones and, occasionally, a trace of a tail-extending muscle. • Appendix Structure which presumably had a digestive function in some of our ancestors, like the cecum of some herbivores. In humans, it varies in length from 5–15 cm, and some people are born without one.

21. Vestigial Structures cont. • Wisdom teeth There are two possible reasons why the wisdom teeth have become vestigial. The first is that the human jaw has become smaller than its ancestors -and the wisdom teeth are trying to grow into a jaw that is much too small. The second reason may have to do with dental hygiene. A few thousand years ago, it might be common for an 18 year old man to have lost several, probably most, of his teeth, and the incoming wisdom teeth would prove useful. Now that humans brush their teeth twice a day, it's possible to keep one's teeth for a lifetime. The drawback is that the wisdom teeth still want to come in, and when they do, they usually need to be extracted to prevent any serious pain.

22. Vestigial Structures cont. Pythons • have tiny femurs (leg bone) Manatees • Fingernails on their fins Blind cave fish • Nonfunctional eyes

23. Anatomical Evidence for Evolution • Strongest anatomical evidence supporting evolution comes from comparisons of how organisms develop. • Early vertebrate embryos possess pharyngeal pouches (gill slits) that develop into: • In humans: glands and ducts • In fish: gills

24. Embryology Evidence for Evolution Developmental similarities reflect descent from a common ancestor

25. EMBRYOLOGY

26. Molecular and Genetic Evidence • All living organisms are made of DNA • Two closely-related organisms will have similar DNA, RNA, and protein (amino acid) sequences. • This also gives evidence of a common ancestor.

27. Convergent Evolution • Biogeography: the study of the geographic distribution of species • Some plants and animals have similar appearance but are only distantly related • Convergent evolution: the independent development of similar structures in organisms that are not directly related • Convergent evolution is usually seen in animals and plants that live in similar environments

28. Convergent Evolution • Marsupials and placentals • Marsupials: young are born in an immature condition and held in a pouch until they develop • Placentals: young are not born until they can safely survive in the external environment

29. Convergent Evolution

30. Convergent Evolution Convergence among fast-swimming predators