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Chapter 5-1 Notes

Chapter 5-1 Notes. Darwin’s Theory. Darwin’s Observation. Species – a group of similar organisms that can mate with each other and produce fertile offspring. Horse and donkey Mule. Galapagos Cormorant Iguanas. Mainland Cormorant Iguanas. Similarities and Differences. Adaptations.

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Chapter 5-1 Notes

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  1. Chapter 5-1 Notes Darwin’s Theory

  2. Darwin’s Observation • Species – a group of similar organisms that can mate with each other and produce fertile offspring. • Horse and donkey • Mule

  3. Galapagos Cormorant Iguanas Mainland Cormorant Iguanas Similarities and Differences

  4. Adaptations • Adaptations – a trait that helps an organism survive and reproduce

  5. Evolution • Evolution – the gradual change in a species over time • Scientific Theory – a well tested concept that explains a wide range of observation • Darwin use selective breeding to produce organisms with desirable traits • Pigeons – only many feather tailed pigeons to mate

  6. Selective breeding must happen in nature. • Darwin’s Theory – the species gradually changed over many generations and became better adapted to the new condition

  7. Natural Selection Natural Selection – the process by which individuals that are better adapted to their environments are more likely to survive and reproduce than other of the same species

  8. Factors Affecting Natural Selection • Overproduction – many offspring produce not enough resources (food, h2o , space) • Competition – food and other resources are limited must compete to survive • Variations – same species differ in traits • Selection – individual survives and reproduces.

  9. Natural Selection – can lead to evolution. • Variation gradually accumulate in a species, while unfavorable ones disappear.

  10. The Role of Genes in Evolution • Mutations – in genes cause variation • Only traits controlled or inherited by genes can be passed on to offspring.

  11. Evolution in Action • Drought on the Galapagos affected the population of finches. • Peppered moths in England

  12. How Do New Species Form? • When a group of individuals remains separated from the rest of its species long enough to evolve different traits. • Kaibab squirrel and Abert squirrel

  13. More Allopatric Speciation • Geographical barriers: mountains, oceans, rivers. A few members of a species manage to cross by a rare chance event. • This is the mechanism by which Darwin’s finches evolved into separate species in the Galapagos islands. Only very rarely can birds cross the ocean to get to other islands. • Or, the barrier develops slowly as conditions change: the gradual formation of the Grand Canyon split a population into 2 isolated groups, that have diverged into separate species, the Kaibab and Albert squirrels.

  14. Continental Drift • Species become isolated when the continent began drifting. • Ex. Australia – most mammals are marsupials. Very few marsupials in other continents.

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