describe the hardy-weinberg principle an genetic equilibrium?

It is at the population level that evolution occurs. A population is a group of individuals of the same species in a given area whose members can interbreed. Because the individuals of a population can interbreed, they share a common group of genes known as the gene pool. Each gene pool contains all the alleles for all the traits of all the population. For evolution to occur in real populations, some of the gene frequencies must change with time. The gene frequency of an allele is the number of times an allele for a particular trait occurs compared to the total number of alleles for that trait.

Gene frequency = the number of a specific type of allele / the total number of alleles in the gene pool

An important way of discovering why real populations change with time is to construct a model of a population that does not change. This is just what Hardy and Weinberg did. Their principle describes a hypothetical situation in which there is no change in the gene pool (frequencies of alleles), hence no evolution.

Consider a population whose gene pool contains the alleles A and a. Hardy and Weinberg assigned the letter p to the frequency of the dominant allele A and the letter q to the frequency of the recessive allele a. Since the sum of all the alleles must equal 100%, then p + q = 1. They then reasoned that all the random possible combinations of the members of a population would equal (p+q)2 or p2+ 2pq + q2. The frequencies of A and a will remain unchanged generation after generation if the following conditions are met:

1. Large population. The population must be large to minimize random sampling errors.

2. Random mating. There is no mating preference. For example an AA male does not prefer an aa female.

3. No mutation. The alleles must not change.

4. No migration. Exchange of genes between the population and another population must not occur.

5. No natural selection. Natural selection must not favor any particular individual.