State and explain any three factors affecting allele frequency in population.

Explanation

Factors which affect allele frequency in populations are called evolutionary agents. These include recombination of genes, mutations, gene flow, genetic drift and natural selection. (a) Recombination of genes involves reshuffling of genes during the process of sexual reproduction. These occur during crossing over and chance arrangement of bivalent during gametogenesis, and chance fusion of gametes during fertilization. (b) Mutations are sudden, large, spontaneous and inheritable changes in the genetic material. These may be either due to gene mutations (change in the number or sequence of nucleotide pairs of a gene) or chromosomal aberrations (change in structure of chromosome) or numerical changes in chromosomes. Mutations may be spontaneous (i.e. natural) or induced (i.e. by man) but are always non-directional. These induce new genes and alleles in a gene pool. (c) Gene flow (also called Gene migration) which involves either emigration or immigration of some individuals which causes loss or addition of some new alleles in a population. Unrestricted gene flow of genetically different individuals and their interbreeding with the members of local population reduces the distinctiveness