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Chapter 15 Evolution

Chapter 15 Evolution. Important Vocabulary. Slide # 2. 1. Species : A group of organisms whose individuals can breed together to produce fertile offspring. 2. Population : A localized group of individuals belonging to the same species .

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Chapter 15 Evolution

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  1. Chapter 15Evolution

  2. Important Vocabulary Slide # 2 • 1. Species: A group of organisms whose individuals can breed together to produce fertile offspring. • 2. Population: A localized group of individuals belonging to the same species. • 3. Evolution: A slow change in a population over time.

  3. Slide # 3 • Charles Darwin explained how Natural Selection could cause a population to adapt and change over time. (note he states- a “population” will change -not an “individual”)

  4. Charles Darwin: An Unlikely Evolutionist Slide # 8 • Charles Darwin • 1809: English born naturalist • Went on a 5 year voyage on the HMS Beagle as an unpaid scholar • Collected plants & animals during journey • Darwin did not set out to develop a theory of evolution • Observations and specimens collected helped Darwin formulate his theory of evolution. Charles Darwin

  5. Darwin’s Observations on the Galapagos Islands Slide # 11 • Fewer types of organisms on the islands • Island species differ from mainland species & from island to island • Finches on Galapagos resemble mainland finch, but there were more types on the islands

  6. Giant Tortoises of the Galapagos Islands Slide # 12 Pinta Tower Marchena Pinta IslandIntermediate shell James Fernandina Santa Cruz Isabela Santa Fe Hood Island Saddle-backed shell Floreana Hood Each island had a variation of tortoise; long & short neck corresponded to type of vegetation. Isabela Island Dome-shaped shell

  7. Darwin explained Evolution by Natural Selection Slide # 13 • 1859: Darwin published On the Origin of Species • Proposed that natural selection was the mechanism for evolution. • Individuals vary in one or more traits & there can be slight differences in their ability to survive & reproduce. • Nature selects those individuals w/ favorable traits to leave more offspring that are better suited (FIT) for their environment. • Decent with modification occurs over time • Each living species has descended, with changes, from other species over time Published 25 years after Darwin wrote it!

  8. Evidence that Supports Evolution: Geographic Distribution of Living Species Slide # 15 • Similar animals on each continent live in similar ecological conditions • They were exposed to similar pressures of natural selection. • Because of similar selection pressures, different animals ended up evolving similar characteristics Beaver Beaver Muskrat Beaver andMuskrat Coypu Capybara Coypu andCapybara NORTH AMERICA Muskrat SOUTH AMERICA Capybara Coypu

  9. Evidence that Supports Evolution: Homologous Structures Slide # 16 • Homologous structures: similar structures but different functions • Structures develop from same clump of embryonic cells • Provides evidence that four-limbed vertebrates descended from a common ancestor. • Vestigial structures: structures or organs that are reduced in size; do not seem to serve a useful function • Homologous & vestigial structures imply that common genes are involved. Homologous structures: forelimbs of vertebrates Pelvis & femur bones are vestigial in whales

  10. Evidence that Supports Evolution: Similarities in Embryology Slide # 17 • The embryos of vertebrates are very similar during early development. • The same groups of embryonic cells develop in the same order and in similar patterns to produce tissues & organs. • Common cells & tissues growing in similar ways produce homologous structures. • Implies that common genes are involved. Embryos of vertebrates develop gill slits and tails.

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