3 The Role of Genes in Evolution Mutations – in genes cause variationOnly traits controlled or inherited by genes can be passed on to offspring.
4 Evolution in ActionDrought 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 DriftSpecies become isolated when the continent began drifting.Ex. Australia – most mammals are marsupials. Very few marsupials in other continents.
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