Evidence for Evolution

1. Evidence for Evolution

2. Homologous Structures • Similar features that originated from a shared ancestor • The presence of homologous features in different species indicates that the species shared a fairly recent common ancestor

4. Analogous Structures • Analogous features serve identical functions and have a similar appearance • They may have different embryologic development and different internal anatomy • Although these features look similar we cannot determine if they share a common ancestor or if these traits evolved independently. • Often organisms with analogous structures share a distant common ancestor but natural selection has further differentiated these structures in recent history

6. Vestigial Organs • Many organisms have features that don’t seem to serve a purpose. • These traits may have been useful to an evolutionary ancestor but are not useful to the modern organisms. • Why do we still have vestigial organs if they serve no purpose?

9. Embryology • In the early stages of development, all vertebrate embryos look similar. • Over time, as the organism develops, they begin to look more distinct • The similarities in early embryonic stages of vertebrates indicating that vertebrates share a common ancestry

11. Guess the Embryo! • http://www.pbs.org/wgbh/nova/beta/evolution/guess-embryo.html

12. Macromolecules • More similar organisms have a more recent common ancestor. • Species that are more similar share more macromolecules in common (homologous proteins) Ex. Hemoglobin • The amino acid sequences for human hemoglobin and gorilla hemoglobin differ by one amino acid • DNA and RNA molecules are also shared by organisms with a shared common ancestor