Exam 21: Variation and Selection in Populations

In forensics, a DNA sample is analyzed to determine which alleles of 13 SSR loci are present.How is the probability of that specific combination of SSR alleles existing in the population calculated?

A large population of fish live in a lake. The color of their scales is determined by two different alleles of the S gene, S1 and S2. Homozygous S1 fish have yellow scales, S2 homozygotes have blue scales, and heterozygotes are green. Scientists catch 100 fish at random and record their color. Among those 100 fish are 30 yellow, 50 blue, and 20 green ones. After the original sample is analyzed, an asteroid landed in the lake and killed all the fish that happened to be in one location. When 100 fish were sampled again, 15 were yellow, 75 were blue, and 10 were green. -What is the frequency of the S¹ allele in the population before the asteroid hit?

Why did the alleles that conferred insecticide resistance in mosquitoes become less frequent in the population when insecticide application was discontinued in the 1960s in Thailand?

Why is the Hardy-Weinberg equation more accurate in predicting genotypic frequencies in the short run than in the long run?