Question

given that a large population which has been living on an isolated is in hardy weinberg equilibrium; what can be said about the relative fitness of the dominant individuals relative to the recessive individuals

Answer 1

Solution

Hardy- Weinberg Equation

Derivation: Take a gene with two alleles; call them A and a. Let A represent dominant individuals and a represents recessive individuals. In a population, some members will have the AA genotype, some will have the Aa genotype, and some will have aa.

p = freq (A)

q = freq (a)

NOTICE that: the frequency of an allele is equal to the probability that a randomly chosen gamete will be carrying that allele. Also notice that p+q=1.

Fitness

Derivation: w in general means “fitness”: a measurement of the relative ability of individuals with a certain genotype to reproduce successfully. w_AA, for instance, means the relative ability of individuals with the AA genotype to reproduce successfully. w is always a number between 0 and 1. Adding ws to the Hardy-Weinberg equation allows you to predict the effect of selection on gene and allele frequencies in the next generation.

Take the Hardy-Weinberg equation and multiply each term (the frequency of each genotype) by the fitness of that genotype. Add those up and you get the mean fitness, w'. Divide through by w', and you get the second equation. Here, each term of the equation is multiplied by the fitness of a genotype divided by the mean fitness. If a genotype is fitter than average, this quotient is greater than 1, and that genotype will increase in frequency in the next generation. If a genotype is less fit than average, the quotient is less than 1, and that genotype will decrease in frequency in the next generation.