PCB 4674C Lecture Notes - Lecture 14: Allele Frequency, Zygosity, Genetic Drift
Document Summary
It is often difficult to determine the limits of a population. For example, in the case of the checkerspot butterfly euphydryas edithae, what appeared to be a single contiguous population was actually several discrete populations with different population dynamics. Consider two populations of a species 1 and 2. We observe one locus with 2 alleles a, a with the following allele frequencies in the two populations: From these allele frequencies we can calculate the expected genotype distribution (hardy weinberg expectation): Note the deficit of heterozygotes if we treated the two populations as one in our h-w expectation. If populations differ in allele frequencies, treating them as a single population will result in a deficit of heterozygotes relative to the hardy. M = fraction of individuals for parents of next generation from surrounding populations f(a) average allele frequency among populations f(a)t+1 = (1-m) f(a)t + m f(a) or f(a)t = f(a) + (f(a)0- f(a)) (1-m)t.
