BIO152H5 Lecture Notes - Lecture 16: Small Population Size, Inbreeding Depression, Allele Frequency
Document Summary
Genetic considerations: small population size, inbreeding, inbreeding depression, genetics and endangered or threatened species. Demographic considerations: immigration/emigration, connectivity: gene flow. Small population size: population bottlenecks, founder effects, genetic drift, result: decrease in genetic diversity. Inbreeding: mating between relatives can be fatal, inbreeding does not cause evolution because allele frequencies do not change in the population as a whole. Inbreeding changes phenotype frequencies but not allele frequencies: genetic consequences of small population size: Inbreeding: mating between relatives, not allowed to mate outside. Becoming less and less heterozygous and more homozygous. Inbreeding depression: results in decline in average fitness in a population when homozygosity increases and heterozygosity decreases. Can increase rate at which natural selection exposes disadvantageous recessive alleles in the homozygous phenotype. Reduction in survival and fertility: inbreeding depression: 2 process. Many recessive alleles; represent loss of function mutations. Certain genes involved in fighting disease have a heterozygous advantage: inbreeding reduces fitness: Gene pool collecting expectation: inbreeding in humans:
