Population Genetics Problem #2

Theodosius Dobzhansky (Genetics 32:142-160; 1947) investigated fitness differences among inversion types of Drosophila pseudoobscura. In one of his population cages he compared the fitnesses of individuals in an experimental population polymorphic for the Standard, $ST$, and the Chiricahua, $CH$, arrangements. He collected the following data:

	Inversion genotype
	$ST/ST$	$ST/CH$	$CH/CH$
Larvae	41	82	27
Adults	57	169	29

Using these data answer the following questions:

1. Are the genotypes in larvae and adults in Hardy-Weinberg proportions?

2. Is the frequency of $ST$ in larvae the same as it is in adults?

3. What is the fitness of the $ST/ST$ homozygote relative to the $ST/CH$ heterozygote?

4. What is the fitness of the $CH/CH$ homozygote relative to the $ST/CH$ heterozygote?

5. What is the expected frequency of the $ST$ chromosome at equilibrium?

6. Are the chromosome frequencies in the experimental population are consistent with the equilibrium expectation?