1. Evidence for Evolution
Biology I

2. Fossil Record SIMPLE to COMPLEX
Of course, the fossil record is not complete – not every organism gets fossilized
Still, there are LOTS of fossils and a simple to complex trend is clearly shown.
Also, transition organisms…

3. Fossil Record – Transition Organism
Tiktaliik Rosea
Transition fossil - from fish to amphibian…
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4. Comparative Anatomy
Comparing the anatomical structures of different organisms to determine their relatedness
Homologous structures
structures in different spcecies
May look different superficially
Similarities indicate a COMMON ORIGIN / COMMON ANCESTOR

5. Example – Homologous Structures
Bones of mammals below show common ancestry

6. Embryology Embryology – the study of embryos
Organisms that are more closely related share similar developmental patterns in their embryos.
Structures that may be absent in adults are found in embryos
Gill slits
Tail

8. Vestigial Organs
Organs that have no function in the organism in which they are found, but DID have a function in an ANCESTOR
Why would an organism waste energy maintaining a useless organ?
They wouldn’t, except that it must be a left over from an ancestor who DID use the organ
Supports the idea of evolutionary change…

9. Example – Vestigial Structure
Human Tailbone

10. Vestigial Organ – Whale hindlimb

11. …also in snakes…

12. Molecular Biology
Analysis of DNA shows us exactly who is closely reltaed to whom by seeing how similar the “letters” of the DNA molecules are between species

13. Molecular Biology Example
Humans and Chimps share 98% of DNA

14. Biogeographical Evidence
Galapagos animals similar to those on mainland S. America rather than those on other tropical islands – Why?
Suggests organisms from S. America came to the islands and changed to fit their new environment
Otherwise, why wouldn’t they be totally different from organisms from mainland– the environment is certainly totally different and much more like other tropical islands.