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LS Chapter 5-3

LS Chapter 5-3. Evolution of Species. Which is the closer relative?. The Role of Genes in Evolution. Mutations – in genes cause variation Only traits controlled or inherited by genes can be passed on to offspring. Evolution in Action.

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LS Chapter 5-3

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  1. LS Chapter 5-3 Evolution of Species

  2. Which is the closer relative?

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

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

  5. 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

  6. 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.

  7. 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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