Problem Set 3

Due Friday January 19

1. A colony of laboratory mice has heritability (h²) of 0.1 for adult weight. The colony keeper wants larger mice, and for the next generation chooses only large mice to mate. Her average large mouse is 5 grams heavier than the population average of 80 grams. Except for this selection, the colony mice mate at random.

A. What will the average weight of the next generation be?

B. What would the average weight be if, unknown to the keeper, some wild mouse genes had gotten into the colony and heritability had risen to 0.6?

2. In Europeans, the frequency of the cystic fibrosis allele is about 0.05. The disease is recessive.

A. What will the frequency of the disease be (at birth) in the next generation of Europeans, assuming random mating?

B. What is the inbreeding coefficient f of first-cousin marriages? (Hint: draw a pedigree.)

C. Given this f, what will the frequency of the disease be (at birth) in a population with the same allele frequency, but where all marriages are among first cousins?