BIO 373 Lecture Notes - Lecture 14: Genetic Drift, Standard Deviation, Switch
Document Summary
Martha"s vineyard island had a fire which affected populations. Increased standard deviation in = increased extinction: genetic factors: impacts small populations by loss of genetic variation, ability of population to respond via natural selection to future environmental changes, and high frequency of inbreeding. genetic drift: process by which chance events influence which alleles are passed onto the next generation. Has little effect on large populations, but in small populations = loss of genetic variation and fixation of harmful alleles. i. inbreeding: mating b/w related individuals. Increases allele frequency of homozygotes (harmful alleles) ii. ex. Combo of genetic drift and inbreeding caused reduction in male fertility of male lions in ngorongoro crater. Outbreak of flies caused all ~75 lions to die but 9 females and 1 male; 7 males immigrated but no further immigration occurred. Population fluctuated from 75-125 from 1975-1990; but all are descendants of only 15 individuals which leads to less genetic variation and more frequent sperm abnormalities.
