ANT 2511 Lecture 5: Anthro-sept 15
Document Summary
Variations: it gives natural selection something to act on, every population has variation. Mutations: occurs when the sequence of the dna is altered, spontaneous- random changes in dna that occur during cell division which can affect anything, induced-caused by a mutagen such as x-rays, uv light, and chemicals. Distributing variation: natural selection, gene flow-increase pop. Natural selection: directional-alleles shift in one direction ex. Human"s big brains: stabilizing- favors the average over the extremes (human birth weight, disruptive- favors the extremes over the average (pygmy mammoths, Ssa but are resistant to malaria: their hemoglobin has oxygen levels too low to support the malaria parasite. Genetic drift: random change in allele frequency over time, caused by small population size (island fauna) and or reproductive isolation ex. Amish- polydactyly is a genetic gene found in only small niches of amish due to the lack of diversity: can lead to one allele being lost and the other fixed in a population.
