Biology 1001A Final: Study notes for Assessment #4 Fall 2011
16 Jan 2012
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Speciation new species, reproductive isolation, gives rise to tree of life (diversity) Mostly biological species concept ie reproductive isolation ie different species do not reproduce with each other. Allopatry separation due to geography physical barrier ie glacier or river or just distance (a founder event colonizing an island) Genetic isolation leads then to genetic divergence (differences arise due to different selective forces, genetic drift??) Isolation and divergence cause speciation (new non-interbreeding species) -> we can test whether the species can interbreed or not (but are they hybrids now???) Small population size allows easier genetic drift (stronger) Different selection pressures on islands versus the mainland --> genetic divergence (selection pressures) ex. Darwin"s finches 14 or 15 species all derived within a few million years from a single finch species from ecuador ex. Hawaii drosophila all descended from common fruit-fly to 100"s of new species. 2 possible outcomes: 1) short-lived separation, little selection pressure, little divergence populations resume interbreeding.
