Question

Short answer question.

Enlist the different factors that are responsible for changing gene frequency.

Answer 1

The four major factors that are responsible for changing gene frequency are as follows:

1. Gene flow (Migration):

Gene flow is the movement of genes into or out of a population. Gene movement may be in the form of migration of organism, or gametes (dispersal of pollens) or segments of DNA (transformation). Thus, gene flow alters gene frequency causing evolutionary changes.

2. Genetic drift:

Any random fluctuation (alteration) in allele frequency, occurring in the natural population by pure chance, is called genetic drift. For example, when the size of a population is severely reduced due to natural disasters like earthquakes, floods, fires, etc. cause the elimination of particular alleles from a population. Smaller populations have greater chances for genetic drift. Thus, genetic drift will result in the change in the gene frequency and has the potential to bring about evolutionary change.

3. Natural selection:

Natural selection is the process by which better adapted organisms grow and produce more offsprings in the population. It brings about evolutionary changes by favouring differential reproduction of genes that bring about changes in gene frequency from one generation to the next generation.

iv. Mutations:

Sudden permanent heritable changes are called mutations. Mutation can occur in the gene, in the chromosome and in the chromosome number. Mutation that occurs within the single gene, is called point mutation or gene mutation or in a larger segment of genes by chromosomal aberrations. Both point mutations and chromosomal aberrations can alter gene frequency. Mutation leads to the change in the phenotype of the organism, causing variation.