Question

A zoologist is investigating a population of squirrels whose coat color is controlled by a single gene whose two alleles (B1 & B2) are co-dominant. B1B1 individuals are black, B1B2 individuals are brown, and B2B2 are tan. She surveys the population and finds 600 black squirrels, 256 brown squirrels, and 112 tan squirrels. Is this population in HWE? If not, what might explain this pattern? Make sure to show your work.

Answer 1

total population = 600+256+112 = 968.

and we have two alleles. so total no of alleles in this population = 2*968 = 1936.

for B1 = 600*2 + 256 = 1456 allele

and B2 = 112*2 + 256= 480 allele.

p = 1456/1936 = 0.752

q = 480/1936 = 0.247

p^2 = 0.75*0.75 = 0.5625

q^2 = 0.25*0.25 = 0.0625

expected number of individuals in each category

p^2 * population = 0.5625* 968 = 544

q^2 * population = 0.0625* 968 = 61

2pq * population = 2 * 0.75* 0.25* 968 = 363

now as you can see that observed and calculated population are not same so the population is not in HWE.

the most obvious reason for this is may be better protection form predators.