Learning Target:Evidence of EvolutionI Can… Describe reasons that provide evidence that evolution occurred throughout the past I Will…• Explain and give examples of

evolutionary evidence from:• Fossil record• Biogeography• Embryology• Anatomy• Homologous structures• Analogous structures• Vestigial structures

Evidence of Evolution: Natural SelectionNatural Selection – Mechanism of how evolution (genetic change over time of a population) happens.• Genetic variation• Selective pressure• Environment• Adaptation (advantage for survival and/or

reproduction)

Right before our eyes • Dog breeds• Antibiotic resistant bacteria• Peppered mothsBut, life has been around for a very long time

Evidence of Evolution: Fossil Record Fossil – traces of organisms that existed in the past mineralized over time “Rock snapshot of organisms in the past”Fossil records shows:• Types of organisms • Structure of the organism• Location, ecosystem they lived in• Age (when they lived)• Rock layers• Deeper = older• Radioisotope dating of surroundings

• Organisms that have become extinct• Changes in populations over time

Evidence of Evolution: Geography

Biogeography – study of the distribution of organism around the world• Organisms from different areas show

similarities• Past migration from common population• New ecosystems exert selective pressure• Adaptations over time• Geography can isolate groups• Prevents mating between separated

groups• Galapagos Finches

Evidence of Evolution: Geography

Galapagos Finches:

Evidence of Evolution: Embryology Embryology – Comparative anatomy study of embryo stage of development in organisms• Different looking adults can have very

similar embryo stage • Fish, birds, reptiles, mammals• All have gill slits in embryo stage• Develops into throat and ear structures

in mammals• Strong evidence of common ancestor

Evidence of Evolution: Embryology

Evidence of Evolution: AnatomyAnatomy – study of structure• Homologous structures • Similar structures with different

function• Result of selective pressure• Strong evidence of common ancestor

Evidence of Evolution: Anatomy Homologous

Common Tetrapod Ancestor

Evidence of Evolution: Anatomy Analogous

Analogous structures –• Different structures with similar function• Selective pressure, such as need for flight,

forced similar traits in different organisms

Evidence of Evolution: Anatomy Analogous

Homologous structures

Analogous structures

Evidence of Evolution: Anatomy VestigialVestigial structures –• Remnants of organs or structures that had

a function in an ancestor, but no longer function in present day descendants

• Very strong evidence for evolution and change over time as selective pressures change

Evidence of Evolution: Anatomy Vestigial

Snakes – Also had a common tetrapod ancestor