evolution2 - Other mechanisms of evolution. Sexual...

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Other mechanisms of evolution. Sexual selection (recognized by Darwin) [Several figures, not in book, but see 23.15, p. 482] . - what about obviously silly characteristics like colors in birds, silly behaviors (e.g. humans), etc.? - Characteristics selected by opposite sex (e.g., females like longer trunk, brighter tails, etc.). - There is often a trade off between sexual selection and natural selection - if character becomes too bizarre, natural selection may put a halt to it. (why does sexual selection exist? - because if you have silly characteristics and can still survive, this indicates you’re doing pretty good.) Speciation - formation of new species. So now that we understand evolution a little bit, how do new species arise? Two possibilities from evolution [Fig., not in book] : - A single species changes - A single species gives rise to several species (origin of diversity) - generally more interesting. First, definition of a species: A group of organisms that can interbreed, but who cannot produce viable offspring with a different species. Even this definition is breaking down in some areas (wolf/dog).
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This note was uploaded on 04/29/2009 for the course BIOL 303 taught by Professor Birchard during the Spring '08 term at George Mason.

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evolution2 - Other mechanisms of evolution. Sexual...

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