1. Evidence for Descent with Modification

2. 1. Direct Observation Guppy coloration HIV resistance

3. 2. Fossil Record Species were different in the past Extinctions Transitional forms

4. 3. Homology Variations on a structure that was present in a common ancestor – Ex: forearm bones of mammals, wings of birds and bats

5. Anatomical Homologies Vertebrate embryos – All have a tail and “throat pouches” during development CatHumanDolphin

6. Vestigial Structures Remnants of features that served important functions in ancestors – Ex: whale pelvic bones

7. Evolutionary Tree Use homologies to create a “tree” that show relatedness

8. Analogy Analogous traits are similar but not due to a common ancestor – Ex: wings of birds and insects

9. Convergent evolution Happens because of similar environmental pressures Organisms do not have a recent common ancestor but resemble one another – Ex: whales and sharks

10. 4. Biogeography Use our understanding of Pangaea and continental drift to search for fossils

11. What Darwin didn’t know…. Now, we compare DNA and proteins to get a better idea of relatedness – More differences = more time since a common ancestor