Answer:

(i) The gene pool i.e., the total genes and their alleles in a population tend to remain constant, This is called genetic equilibrium. Sum total of all allelic frequencies is 1 Individual frequencies, can be named p,q, etc. In a diploid, p and q represent the frequency of allele A and allele n. The frequency of AA individuals in a population is simply p2. This is simply stated in another ways, i.e., the probability that an allele A with a frequency of p appear on both the chromosomes of a diploid individual is simply the product of the probabilities, i.e., p2. Similarly of aa is q2, of Aa 2pq. Hence, p2 +2pq + q2 = 1. When frequency measured, differs from expected values, the difference (direction) indicates the extent of evolutionary change. Disturbance in genetic equilibrium, or Hardy- Weinberg equilibrium, i.e., change of frequency of alleles in a population would then be interpreted as resulting in evolution.

(ii) Mutations, recombinations during sexual reproduction, genetic drift, gene migration or gene flow, and natural selection are the major factors that influence genetic equilibrium and cause variety in the population.