1. Which of the following population(s) is/are in Hardy-Weinberg equilibrium? What are the expected genotypic frequencies for those populations that are not in equilibrium? How long will it take for these equilibrium values to be reached under random mating?
|
|
Genotypes
|
|
Population
|
AA
|
Aa
|
aa
|
|
I
|
.4225
|
.4550
|
.1225
|
|
II
|
.0025
|
.1970
|
.8005
|
|
III
|
.0081
|
.0828
|
.9091
|
2. In polled cattle a shapeless, horny growth sometimes develops where the horns would normally be located. This condition, called scurs, appears to be controlled by a gene with two alleles (S and S') acting in a sex-influenced manner. The allele causing scurs (S') acts as a dominant in males and as a recessive in females. That is, SS in both sexes is normal, and S'S' in both sexes is scurred, while SS' is scurred in males but normal in females. Assume i.) in a herd of 236 polled cows (females), that four of the cows had scurs, and ii.) that the herd is in Hardy-Weinberg equilibrium.
a. What is the frequency of the scur allele (S') in this population of cows?
b. How many cows in this population of 236 polled cows are expected to be heterozygous for the scur trait?
c. If 100 of the next 236 calves were bull calves, how many bull calves would you expect to eventually develop scurs?
3. Assume you are selecting individuals in your dairy herd as breeding stock. If the current herd production is 15,000 lbs milk / lactation, the average of the selected individuals is16,500 lbs milk / lactation, and the heritability (narrow sense) is 0.30, what is the expected milk production for the offspring of these selected parents?