Evidence of Evolution

What is evolution?• Definition:– The gradual change in a

species over time• Takes a Looooong time• Results from a change in

the GENETIC material of an organism– Not acted on at the

individual level– Passed on from one

generation to the next

What is a theory?• Based on a careful examination of facts• Well supported explanation of some aspect of

the natural world based on knowledge that has been repeatedly confirmed through observation and experimentation.

What evidence do we have for evolution?

• Similarities of structures in living things– Analogous Structures– Homologous Structures– Embryo development (early stages)– Vestigial Organs

• Shared Ancestry– The fossil record– Biogeography

Analogous Structures• Similar function– Ex. Used to fly

• Different structure– Ex. Different

arrangement of bones

• Different origins– Do not have a

common ancestor

Homologous Structures• Different function– Adapted to different

purposes– Humans arm is used

differently than a whales fin• Similar structure– Same basic arrangement of

bones• Same origin– Common ancestor

Embryology• Embryos develop similarly in many vertebrates

Vestigial Structures• Inherited structures that no longer serve a

function for the organism• Examples – Hipbone in dolphin/whale– Our appendix– Our wisdom teeth

Shared Ancestry

• Shared Ancestry– The fossil record– Biogeography

The Fossil Record• Found fossils that show slow progression of

change• More found since Darwin

Biogeography

• Found animals in isolated islands or environments that ended up being perfect for that area after generations

• Where they are now compared to then– Patterns in different places tell how organisms

evolved– Populations on different islands all look different…

• Originate from a mainland

• Ever hear of the Galapagos Islands?

Ex: Galapagos Islands

South America

Darwin = populations on islands evolved from mainland species

Change over time…

• Depending on the food source and environment, different birds survived and changed to best fit each island

Situations

• One of the islands on the Galapagos has a relatively large mountain system on it. Because of it, there is a lot of crack and tight spaces things fit in. As for seeds birds eat, they often fall into the think cracks. Which bird is most likely the one that thrives there? Why?

Natural Selection• Darwin’s Finches– Beak specialties– Common ancestor– Natural selection takes place frequently and rapidly– Variation increases chance of adaptation