1) The genetic basis of pelage variation in beach mice has been traced to point mutations in the MC1R locus. Three color morphs, brown, white and intermediate, are present in the population. Each of these morphs is associated with a particular genotype. Thus, brown beach mice are homozygous for the wild-type allele (bb), intermediate (beige) beach mice are heterozygous (bw), and white beach mice are homozygous for the mutant-type allele (ww). Genotyping (based on counts of the three phenotypes) of a random sample of beach mice from the Alabama and the Florida Gulf Coast is shown in Figure 1. Figure 1: Pie charts show frequencies of the light (w) and dark (b) alleles of the melanocortin 1 receptor (Mcl1r) coat-color locus (represented as light and dark segments, respectively) in coastal beach mouse populations, with typical coloration for each subspecies. Mc1r polymorphism controls coat-color differences between western populations, but not on the east coast of Florida. The number of individuals sampled is provided. a. There were 13 brown mice in the Perdido Key sample, 2 in the Santa Rosa Island sample, and 6 in the St. Andrew’s beach mouse sample. Based on this information, what are the expected heterozygosities of the mice on each island? What is the Fst of the population of beach mice comprising the 3 islands? (6 points) A table and equations are shown to ease your calculations. Island frequency (b) frequency (w) Expected heterozygosity Perdido Key Santa Rosa Island St. Andrew’s Average Hs HT = 2 * average(p) * average(q) FST = (HT – HS)/ HT
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Hs is a measure of genetic diversity within a population and is calculated using the formula Hs = 2 * average(p) * average(q), where p and q are the frequencies of the two alleles (b and w). For Perdido Key: - There were 13 brown mice, which means the frequency Show more…
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