Define the terms : a) Gene Flow b) Genetic drift.

Explanation

(a) Gene flow : Gene flow is defined as the transfer of genes between two interbreeding populations which differ genetically. Migration and hybridization are the chief sources of gene flow. The gene flow pattern decides the gene frequency of a population. (b) Genetic drift or Sewall Wright effect : It is defined as "Rando changes in gene frequency in a small interbreeding population happen purely by change". As a result of genetic drift, some genes may be reduced or increased in frequency. Some of them may even be lost by chance. This genetic drift leads to the fixation or loss of certain genes irrespective of their adaptive value.