Answer 1

Gene mutations, gene flow, genetic recombination, genetic drift and chromosomal aberration are some factors responsible for genetic variation.
 Gene mutations: These involve changes in the chemical constitution of a gene. They introduce variations in the gene pool and are responsible for the change in the gene frequency.
 Genetic recombination: Organisms reproducing sexually undergo gametogenesis during which the homologous chromosomes exchange genetic material by the process of crossing over. This produces new combinations of genes resulting in genetic variation.