Question

A hypothetical population of 16000 squirrels has two alleles, F^B and F^W, for a gene that codes for fur color. The table below describes the phenotype of a squirrel with each possible genotype, as well as the number of individuals in the population with each genotype.

genotype	phenotype (fur color)	# individuals in population
FBFB	black	8000
FBFW	gray	6000
FWFW	white	2000

In this population, p=0.6875 and q=0.3125. The expected numbers of individuals with each phenotype are 7562.5 black, 6875 grey, and 1562.5 white. Researchers carry out a χ² statistical test and determine that P<0.001. Choose all the statements below that correctly describe what is or could be happening in this population.

		This population is in Hardy-Weinberg equilibrium.
		This population does not appear to be experiencing the effects of natural selection, drift, gene flow, mutation, or inbreeding.
		This population could be experiencing natural selection favoring the homozygotes because the observed number of each homozygote is higher than expected and there are fewer heterozygotes than expected.
		The population could be experiencing the effects of mutation since there is a significant difference between the observed and expected values.
		This population is NOT in Hardy -Weinberg equilibrium.
		The population could be experiencing the effects of inbreeding since there are more homozygotes than expected and fewer heterozygotes than expected.

Answer 1

Ans :

This population is in Hardy-Weinberg equilibrium.

This population does not appear to be experiencing the effects of natural selection, drift, gene flow, mutation, or inbreeding.

Reason :

We have p = 0.6875 and q = 0.3125

According to Hardy - Weinberg equilibrium,

p + q = 1

Substituting p and q values,

0.6875 + 0.3125 = 1, which indicates this population is in Hardy - Weinberg equilibrium.

Also it satisfies,    p2 + 2pq + q2 = 1

p2 = 0.68752 = 0.472

2pq = 2 x 0.6875 x 0.3125 = 0.430

q2 = 0.31252 = 0.098

Substituting these values in equation  p2 + 2pq + q2 = 0.472+0.430+0.098 = 1.

This also show that population is in Hardy - Weinberg equilibrium.

Since population is in Hardy - Weinberg equilibrium, then there will be

• No mutation,
• No gene flow
• No genetic drift
• No selection
• No inbreeding (only random mating)