Write short note on Hardy - Weinberg principle.
In $1908$, $GH$ Hardy and $W$. Weinberg established a simple mathematical relationship to the study these genes frequencies and gave Hardy - Weinberg principle.
This principle states that the allele frequencies in a preparation are stable and is constant for generation to generation i.e. gene pool remains constant.
This is called genetic equilibrium or Hardy - Weinberg equilibrium.
In a given population one can find out the frequency of occurance of allele of a gene or locus.
This frequencies is supposed to remain fixed and even remain the same through generations.
Hardy - Weinberg principle stated it using algebraic equations.
This principle says that allele frequencies in a population are stable and is constant from generation to generation.
The gene pool (total genes and their allele in a population) remains a constant.
This is called genetic equilibrium.
Sum total of all allelic frequencies is $1$ .
Individual frequencies, for example can be named $\mathrm{p}, \mathrm{q}$ etc.
In a diploid, $p$ and $q$ represent the frequency of allele $A$ and allele $a$.
The frequency of $AA$ individuals in a population is simply $\mathrm{P}^{2}$.
This is simply stated in another ways i.e. the probability that an allele A with a frequency of P appear on both the chromosomes of a diploid individual is simply that product of the probabilities i.e. $\mathrm{P}^{2}$.
Similarly of $\mathrm{a}^{\mathrm{a}}$ is $\mathrm{q}^{2}$, of Aa. $2 \mathrm{pq}$
Hence $\mathrm{P}^{2}+2 \mathrm{Pq}+\mathrm{q}^{2}=1$
This is a binomial expansion of $(\mathrm{p}+\mathrm{q})^{2}$
When frequency measured, differs from expected values the difference (direction) indicates the extent of evolutionary change.
Disturbance in genetic equilibrium or Hardy - Weinberg equilibrium i.e. change of frequency of alleles in a population would then be interpreted as resulting in evolution.
Factors affecting Hardy - Weinberg equilibrium : Five factors are known to affect Hardy - Weinberg equilibrium.
These are gene migration or gene flow, genetic drift, mutation, genetic recombination and natural selection.
Random genetic drift in a population probably results from
If gene migration happens multiple times, it would lead to
Hardy Weinberg equilibrium is affected by -
In a random mating population in equilibrium, which of the following brings about a change in gene frequency in non-directional manner?