BIO220H1 Lecture Notes - Lecture 4: Extinction Vortex, Genetic Drift, Nucleotide Diversity
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Document Summary
Small population greater genetic drift loss genetic variety gene frequency decrease. Inbreeding arises homozygosity increases inbreeding depression lower fitness. Risk of demographic stochasticity (random differences of fitness and reproductive success) or happens even when no random differences (average fitness and reproduction) reduce fitness when low population. Allele effect: correlation between population density and fitness. If a population has only 2 male and 2 females, if any random chance event prevented these individuals from reproducing, our population growth rate would = 0. Genetic hypothesis: low population will drive the population to extinction furthermore. Demographic hypothesis: demographic stochasticity should result in extinction (before genetic can cause the extinction). Low genetic diversity, low heterozygous loci in individuals. Lack genetic difference low variety in mhc locus e. g. organism will not reject other cheetah"s skin grafts. More susceptible to diseases could wipe them out (like the potatoes) Captive cheetahs have low sperm number, carry many diseases.
