The Evidence for Evolution

1. The Evidence for Evolution

2. Evidence of Evolution #1 – Fossil Record • 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

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

4. Fossil Evidence of Evolution • Fossil of Archaeopteryx : It is intermediate between bird and dinosaur • Possesses some ancestral traits and some traits of present day birds

5. Fossil Evidence of Evolution Whale “missing links”

6. DivergentEvolution • when one species becomes many different species to fill available niches • Adaptive Radiation: periods of evolution in which organisms form new species due to adaptations that allow them to fill different niches in the community. i.e. Darwin’s Finches on the Galapagos Islands • Homologous Structures

7. Evidence for Evolution #2 – Morphology • Homologous Structures -Similarity in structure due to common descent (had a common ancestor), regardless of the different environments in which they now live; same structure, different function i.e.- human hands, whale fins, bat wings

8. Evidence for Evolution #2 – Morphology

9. Evidence for Evolution #2 – Morphology

10. Convergent Evolution • the appearance of apparently similar structures/ features in organisms of different lines of descent. • Analogous structures • Birds & Bats • Dolphins & Sharks • Penguins & Seals

11. Evidence for Evolution #2 - Morphology • Analogous Structures - Similar structures based on naturally selected adaptations for the same function in different organisms but that did NOT result from a common ancestor • i.e – wings in birds, bats, insects

13. Mimicry • A phenomenon in which an individual gains an advantage by looking like the individuals of a different species. • “A mimic is any species that has evolved to appear similar to another successful species in order to dupe predators into avoiding the mimic, or dupe prey into approaching the mimic.”

14. Monarch Viceroy

15. Evidence for Evolution #2 - Morphology • Vestigial Structures - Remnants of once useful structures (in ancestral species) but that no longer serve a purpose in this specific species (although could still be useful in similar species) i.e. – human appendix, hind limbs of snakes and whales

16. Vestigial structures of a whale

17. Hip girdles on snake

18. Blind Salamander

19. INTRODUCTION TO EMBRYOLOGY

20. Human Embryo • Cat and human embryos in the tailbud stage. A cat embryo is shown on bottom, a human embryo on top. Note the post-anal tail in both, positioned at the lower left below the head of each. The human embryo is about 32 days old. Cat Embryo

22. OOPS!

23. Evidence of Comparative DNA • All creatures on Earth are descendents of a common ancestor. • Therefore: • we have the same mode of inheritance • Genes on chromosomes made of DNA • Why we have similar nucleotide and gene sequences

24. Evidence of Comparative DNA

25. Evidence of Comparative DNA