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Unformatted text preview: Biol 201- Ecology and Evolution- 2 nd ss Review for Exam 1 Evolution: Darwin defined it as descent with modification Over a long time ( macroevolution )- trace all organisms back through a series of common ancestors o Evidence : structural homology (arm bone presence in humans, bats, and whales), relatedness of life forms (comparative embryology), biogeographical relationships among species (Darwins finches and beak size), change through time (direct observation- balloon vine fruit and flat-podded golden rain tree fruit and insect beak length change with change in precipitation decrease)- The Law of Succession, vestigial traits in living organisms (pelvis and femur in whales and snakes), transitional forms (of the vestigial traits in closely related species), Over a short time ( microevolution )- evolution is a change in gene frequencies within a population Macroevolution takes too long to observe directly (it occurs through micro-evolutionary processes that can be measured over the short term) Darwins Theory of Evolution by Natural Selection: 1. There is considerable variation among individuals (of the same species!) 2. Some of these variations are heritable (theyre passed on from parents to offspring) 3. More offspring are produced than can possibly survive 4. Survival of the fittest! (the survival and reproduction of individuals is NOT random: some individuals with favorable variations produce more offspring than those without them)...
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