Question

Natural selection and genetic drift are two mechanisms that affect allele frequency at genetic variants in the population. Describe how each mechanism can affect allele frequency.

Answer 1

Allele frequency will change due to natural selection and genetic drift. They are the most relevant sources that affect allele frequency.

Natural selection allows the best one to survive and reproduce. If the chance of surviving of reproduction increases ,the frequency will also increase. If the allelese decreases , the chance of survival and reproduction should be less. And it further results in the deceases of frequency of harmful alleles in genepool . When the environmental changes occur, phenotypes of different types will selected and this phenotypes are determined by the genotypes. The successful genotype increases the frequency in genepool. The unfavourable allele decreases the frequency while the favourable allele increases the frequency.

Genetic drift consists of random changes in appearance of gene's frequency , usually in a small population. This may cause the genetic variability to reduce by the complete disappear of gene variants. In large population, the effect of genetic drift is smaller but in small population it is large . Some alleles are completely lost within a generation due to genetic drift. This loss of allele from gene pool is occured by the changes in allele frequency.