# (a) Explain Hardy-Weinberg Principle on the basis of the algebraic equation (b) How do gene migration and genetic drift affect this genetic equilibrium ?

(a) Hardy – Weinberg Principle
Hardy – Weinberg Principle explains the existence and consistency of gene frequency for a distinct gene. It states that the allelic frequency remains constant through generations and the gene pool remains fixed. This phenomenon is called genetic equilibrium.

Also, all the allelic frequencies sum up to 1.

Let's assume, the frequency for the allele X in a population is a and that of the allele x is b.

So, the frequency of XX is a2, xx is b2 and Xx is 2ab.

The equation can thus be represented as

a2 + b2 + 2ab = 1 or (a + b)2 = 1.

(b) All these factors contribute to the change in gene frequency of a species in an area. If a few individuals from a species migrate to another place, the gene frequency changes again. It decreases from the place from where the individuals migrate and increase in the place they migrate to.

If the number of the genes is high adequate in the newly migrated land to start a new species, the migrated individuals become the founder species, and the effect is called the founder effect.

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