BIOL359 Chapter Notes -Cystic Fibrosis, Allele Frequency, Zygosity
8 Oct 2013
School
Department
Course
Professor
Document Summary
Differences in survival and reproduction of phenotypes, leading to differences in their contribution to the next generation, resulting in a change in the frequency of heritable phenotypic variations in populations over time. Relies on darwin"s postulates: species are variable, variations are heritable, more offspring produced than survive, survival is not random. Antagonistic selection may occur when two components of selection oppose each other. May be point mutations (transitions and transversions), insertions and deletions (indels). Achieves a mutation-selection balance (mutation introduced and removed from population at the same rate). The cane toad: selected for small snake size, because large snakes died when they fed on it. Lake erie water snakes: populations on island contain banded snakes because of migration from the continent. Chance fluctuations of allele frequencies as a result of randomly sampling gametes in each generation. Founder effect occurs when new population is founded by a small number of individuals and has a higher frequency of an allele.
