Please give me an example regarding Hardy Weinberg equilibrium?

Question

Hi. Im having trouble understanding the concept. I know the HW Eq. regards population. Please give me an example of that

Answer 1

By comparing genotype frequencies from the next generation with those of the current generation in a population, one can also learn whether or not evolution has occurred and in what direction and rate for the selected trait.  However, the Hardy-Weinberg equation cannot determine which of the various possible causes of evolution were responsible for the changes in gene pool frequencies.

It is important not to lose sight of the fact that gene pool frequencies are inherently stable.  That is to say, they do not change by themselves.  Despite the fact that evolution is a common occurrence in natural populations, allele frequencies will remain unaltered indefinitely unless evolutionary mechanisms such as mutation and natural selection cause them to change.  Before Hardy and Weinberg, it was thought that dominant alleles must, over time, inevitably swamp recessive alleles out of existence.  This incorrect theory was called "genophagy" (literally "gene eating").  According to this wrong idea, dominant alleles always increase in frequency from generation to generation.  Hardy and Weinberg were able to demonstrate with their equation that dominant alleles can just as easily decrease in frequency.

Answer 2

That's a little impossible; the whole point of the Hardy Weinberg equilibrium is that it can't happen, thereby showing the impact of natural selection. If you want to know the equation for the gene pool, it's

P^2 + 2PQ + Q^2 = 1, the same thing as (P+Q)^2.

Basically, a series of conditions must be met, including no natural selection, no migrations, completely random mating, and no mutations in an ENTIRE population. Just by looking at those first few (that doesn't even cover the entire list of conditions), you can see that HW equilibrium is statistically impossible. Hope that helps some.