Question

Why is the effect of genetic drift relatively "strong" (i.e. can potentially cause larger change in allele frequency from generation to generation) in small populations and relatively "weak" in large populations? Include the following terms in your answer: gene pool, gametes, sampling error.

Answer 1

Genetic drift is the variation in the relative freequency of different genotype in a small population ,owing to the chance disappearance of particular genes as individual die or do not reproduce.

This can be explained by the ' marble on jar ' experiment. That is if a population have 20 individual. In which 10 males amd 10 females are there. Now males and females contain different genes. That is in the gene pool there are different kind of gene stock.When a female gamete is fused with male gamete the offspring produce.Now the offspring may get the genotype of both mother and father but phenotypically they will show one expression of gene inherited from either mother or father that is called 'selection'.This way when particular genes are getting selected during reproduction , that selected gene becomes 'fixed' and then the genotypes of the gene pool gets altered and remain in that stage unless a new allele is introduced.

Now if the population is small this fixation can take place earlier and therefore genetic drift refers to be ' strong' in case of small population. But when the population is large then this fixation takes longer time and during which there can be entry of another alleles and the diversity of genotype in a large gene pool makes the process complex aand less effective.And thus large population gets weak effect of genetic drift.