Evidence of Evolution Unit 3-4 Notes Mr. Hefti – Pulaski Biology

Here are 6 of the most compelling forms…

1. Fossils Most complete form of evidence Sedimentary rocks form layers that preserve outlines or remains of organisms for millions of years

Sediment layers preserve order

Horse evolution as told by fossil record

2. Geographic distribution of organisms Organisms have specific environmental requirements Some organisms possess limited ranges

3. Comparative anatomy features A. Homologous structures - Similar structures that serve different functions

3. Comparative anatomy features B. Analogous structures - Different structures that serve the same functions

3. Comparative anatomy features C. Vestigial structures - Structures that now serve no apparent function (but did at one time)

4. Similarities in embryonic development All vertebrate organisms look very “tadpole-like” early on in their development due to a common set of genes controlling early development - Homeobox genes

5. DNA similarities All living things possess DNA that carries their genetic code Unicellular bacteria and multicellular trees possess unique combinations of A, T, C, and G

6. CHON All living things include these 4 elements: –Carbon –Hydrogen –Oxygen –Nitrogen