LIFE 102 Lecture Notes - Lecture 23: Genetic Variation, Gene Flow, Allele Frequency
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Ch. 18, 19, 21, 22, 23, 24: group final exam dec. 9. The galapagos was particularly informative for darwi(cid:374)"s research. Homology is shared characteristics due to shared decent. What are the necessary conditions: no mutation, random mating, no natural selection, large population size, no gene flow. Genetic drift- variation in the frequency of alleles in a population due to the chance disappearance of alleles through death or failure to reproduce. Key is chance- random events that result in changes in allele frequencies. Impact of random events is magnified in small populations. Bottlenecks- a severe drop in population size that results in loss of alleles in a population that is the surviving population. Common examples are endangered species but also important in human genetics. A bottle filled with marbles, pour out some of the marbles that can escape the bottle, Founder effect- small numbers of individuals colonize an isolated area, involves movement to a new area.
