BIOL 121 Study Guide - Midterm Guide: Allele Frequency, Environmental Disaster, Genetic Drift
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BIOL 121 Full Course Notes
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Document Summary
Homology: evidence of descent from a common ancestor. (1) genetic - in dna (2) developmental - in embryo (3) structural - morphology. Evolution by natural selection occurs when (1) heritable variation leads to (2) different reproductive success. Steps leading to evolution of finches: normal distribution of beak size, environmental disaster (less rain) led to biotic change, directional shift in beak size. Sexual selection (1) intrasexual selection: male-male competition (2) intersexual selection: female chooses. Eggs are expensive and rare, while sperm are cheap and plentiful. Mothers spend more time ensuring the offspring will survive. Higher investment - more picky when choosing a male. Thus, males develop characteristics to attract a female. Consequences for males: (1) be fabulous (2) do something fabulous (3) make more sperm (4) make higher quality sperm. Evolution: a change in allele frequency in a population. Gene pool: involves all of the gametes in a population.
