1. You are studying the nesting behavior of an unusual species of bird in the Solomon Islands. You discover that baby birds exist in two color morphs, grey or yellow on the island of Choiseul. You estimate that the population includes 263 yellow baby birds and 413 grey baby birds (676 total). You don’t have a genome for this species so you aren’t sure about the genetic basis of color but you assume that color is controlled by two alleles at a single locus.

There is no difference between yellow and grey baby birds once they have matured but yellow baby birds have a higher risk of predation. If 303 grey babies survive to adulthood, but only 150 yellow ones do, calculate the fitness of the yellow phenotype relative to the grey one. For this this question assumes grey is dominant

0.78

Explanation:

Fitness measures the probability of survival and reproduction of a particular phenotype or genotype in a population.

Relative fitness measures how fit one genotype or phenotype is with respect to the most fit genotype or phenotype in a popualtion. It is calculated as = survival rate of that group / maximum survival rate observed in that population

Here,

Total number of yellow birds = 263

Yellows birds that survived = 150

Survival rate of yellow birds = 150/263 = 0.57

Total number of grey birds = 413

Grey birds that survived = 303

Survival rate of grey birds = 303/413 = 0.73

Grey birds have more survival rate than yellow birds so their survival rate is maximum in the population.

Fitness of yellow phenotype relative to grey phenotype = survival rate of yellow birds / survival rate of grey birds

= 0.57 / 0.73

= 0.78

Hence, fitness of the yellow phenotype relative to the grey one is 0.78.