1. Evidence of Evolution Sec 8.2

2. Biogeography  The study of the past and present geographical distribution of species populations  Many of Darwin’s observations were based on biogeography

3. Example 1  Geographically close environments are more likely to be populated by related species than are locations that are geographically separate but environmentally similar.  Desert and forest in South Africa vs. desert in Africa and forest in Australia.  Ie. Cacti are found in North, Central and South America deserts, but not in any other deserts.

4. Example 2  Animals found on islands often closely resemble animals found on the closest continent.  Suggests island animals have evolved from mainland migrants with populations adapting over time to their new home.  Ie. Lizards in Canary islands (NW African coast) are similar to those in West Africa

5. Example 3  Fossils of the same species can be found on the coastline of neighboring continents.  Continent location is not fixed and continents are slowly moving away from one another.  Africa and south America were once joined.

6. Example 4  Closely related species are almost never found in exactly the same location or habitat.

7. Evidence from Anatomy

8. Homologous structures  Structures that have similar structural elements and origin but have a different function.  Similar because they were inherited from a common ancestor.  Differ in anatomy based on an organism’s lifestyle and environment.

10.  Can be similar in structure r function or both.  The lower limbs of the human, frog, and horse all perform movement on land.  Hair in mammals is homologous – similar structures but may have different functions.

11. Analogous structures  Structures of organisms that do not have a common evolutionary origin but perform similar functions.  The wings of insects, birds, bats and pterosaurs (extinct flying reptiles) are similar in function but not structure, which means they do not share a common ancestor with wings.