Name 2 vestigial structures in the human body. Evidence of Evolution Good Morning!! Warm Up: What is the difference between homologous and analogous structures? Name 2 vestigial structures in the human body.

Evolution – a long, slow change over time Charles Darwin His observations became the theory of evolution Noticed species seemed well adapted to environment and that different species were found in different parts of the world Galapagos Islands Species characteristics differed from island to island Darwin’s Finches Birds had structures that fit their island

The Galapagos Islands & Darwin’s Finches

Natural Selection – Darwin’s proposal Also known as Survival of the Fittest Adaptations – inherited trait (physical or behavioral) that increases an organisms chance for survival and reproduction (Fitness) Ex: long neck and legs of giraffe Fitness – combination of physical traits and behaviors that helps an organism survive and reproduce.

Structural adaptations in giraffes

Behavioral Adaptations in wolves 5 minutes

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Evidence of Evolution Evidence of Evolution is based on: 1) Fossil record 2) Embryological evidence 3) Structural evidence 4) Biochemical evidence (the DNA biomolecule)

Fossils – preserved remains of ancient organisms Paleontologist – scientists who study ancient life through fossils Most fossils form in sedimentary rock Very few organisms become fossils Question: In a rock layer, where would the oldest fossils be found?

Which layer is the oldest? Dating Fossils

Embryological Embryos of different species begin life looking very similar indicating similar genes at work. Evolution: Library: Common Past, Different Paths

STRUCTURES: Homologous structures – same structure different function Ex: human arm, bird wing, whale flipper, dog leg Evolution: How Do We Know Evolution Happens?

Divergent Evolution & Homologous Structures

Vestigial structures – remains of structures or organs no longer needed for survival (usually become reduced in size) Ex: leg bones in snakes, human appendix

Vestigial Structures Example: whales’ femur (leg bone) and pelvis

BIOCHEMICAL EVIDENCE Biochemistry- DNA (biomolecule) evidence The best way to test the relatedness of two species is by the similarity of their DNA proteins. The more closely related two species are, the fewer their amino acid differences.

The history of Earth helps explain the current geographical distribution of species. 250 million years ago all the land masses were joined into one supercontinent, Pangaea. 180 million years ago, Pangaea began to break up into separate continents. Continental Drift

Divergent Evolution (adaptive radiation) - One species (common ancestor) gives rise to many and they become less alike because they are in different environments. - Creates homologous structures (different function, same structure) - Like a tree with common ancestor as trunk and branches representing new species arising from it.

Common Ancestor

Convergent evolution - Unrelated species become more alike in behavior and appearance because they share a similar environment. This type of evolution creates analogous structures – similar in function and appearance but have different origins. Same function, different structures EX: Butterfly wing – Bird wing Like two separate trees growing close together. Close branches may show convergent evolution. DO NOT SHARE A COMMON ANCESTOR

Analogous structures

Live in similar environments so evolve similar characteristics but not very related Ancestor 2 Ancestor 1

Coevolution: When 2 organisms evolve together because they have a large affect on each other. This usually happens if the 2 organisms are in symbiosis. Can look like they are “one upping” each other.

Coevolution is when unrelated organisms evolve together because they have some sort of symbiotic relationship