Understanding the Evidence of Evolution: Key Concepts and Findings

1. Evidence of Evolution By Madalyn Incognito

2. The 5 evidences of evolution: • Fossils • Biogeography • Comparative embryology • Comparative anatomy • Comparative DNA (Biochemistry)

3. Fossils • A fossil is a remnant or trace of a once living organism • How are fossils formed: • The animal dies • Soft parts of the animal are eaten or decay; the bones remain • The bones or hard parts are covered in dust and soil • Bones are buried in layers of soil • The layers of soil turn to stone. The remains turn to stone and form a fossil • Fossils show that life forms found in fossils from millions of years ago have similar characteristics to modern life forms. It proves they originated from a common ancestor.

4. Dating of Fossils • The age of rocks can be determined using radioactive dating • The age of rocks can also be determined by correlating the fossils found in them with rocks of know age • The oldest sedimentary rocks contain no fossils; no evidence of life • Older fossils are from organisms which were: • Simple • Water living • Younger fossils are from organisms which were: • Both simple and complex • Both water and land living

5. Biogeography • Biogeography is the study of living things in relation to geographical regions • Darwin and Wallace used biogeography as evidence of evolution. • They noticed that species living in the same area were more similar to each other than to species living in similar habitats far apart • This shows that species evolved due to the selective pressure of their own habitats

6. Emu-Australia Rhea-South America Biogeography tells us that organisms migrate from a place of origin and evolve into new species. Ostrich-Africa

7. Comparative Embryology • Comparative Embryology is the branch of Embryology that compares and contrasts embryos of different species. • Comparative Embryology determines that relatedness of species. Organisms with similar structures are argued to have acquired theirtraits from a common ancestor.

8. Comparative anatomy • The anatomy of different species can be compared to look for evidence of evolution from a common ancestor. • Homologous structures: • Structures found in plants or animals that have the same origin, but not necessarily exactly the same formor the same function • Example: Pentadactyl limb of vertebrae animals (mammals, reptiles and amphibians)

9. All vertebrae animals have limbs with five digits (finger-like structures) which have the same basic structural plan but have altered to different environments and lifestyles • This suggests that all these groups of animals originated from a common ancestor

10. Comparative DNA sequencing • Comparison of the DNA sequences allows organisms to be groupedby sequence similarity and as a result allows the construction of evolutionary trees • Comparative DNA sequencing shows that we all come from a common ancestor • We all have the same bases in our DNA, they are just arranged in different order • The more closely related the animals are the more similar their DNA sequence is • Example: • If 2 new species evolved from a common ancestor, their DNA and protein molecules would change and become different. The number of differences is proportional to the time since they separated