Biology 1201A Lecture Notes - Lecture 17: Dwarfism, Inbreeding Depression, Zygosity
Document Summary
Forces that do not keep populations in hwe. Selection: acts on phenotype, can measure effect by fitness, often reduces allele variation, ultimate sources of variation, eg: immigration or migrations, adds genetic variation within a population. Genetic drift: eg: bottleneck effect, reduces genetic variation within a population. Non-random mating: changes genotype frequencies, but not allele frequencies, assortative vs dis-assortative, inbreeding vs outcrossing. Any movement of individuals (or genetic material) from one population to another. Adds new alleles, genetic variation within a population. Can also disperse seeds, all organisms have some sort of gene flow. Change in allele frequencies due to the effect of chance. By chance some individuals may not reproduce. Or by chance only a small subset of individuals reproduce. Bottleneck effect: due to sampling a very small number, change in allele frequency by chance. Small number of founders that create a new population. Reduced capacity to cope with environmental change. Eg: cheetah"s -> poor sperm, palate erosion, kinked tail.
