Question

Explain why we use the concept of Hardy-Weinberg Equilibrium if populations are never stable. What do the mathematical results tell us if the allele frequencies do not match our predictions? (In other words, if you have extra spotted fish in a generation, what has happened?)

Answer 1

Hardy Weinberg equilibrium tells us that the allelic and genotypic frequencies do not change from one generation to the next if the population under study is not evolving. If a population is undergoing evolution, then the allele and genotypic frequencies change from one generation to the next.

Thus, Hardy Weinberg equilibrium is useful to check whether a population is evolving or stable. If the predicted allele frequencies do not match with the mathematical results, then it indicates that the population is under evolution, and allele frequencies are changing from one generation to next.

This change in allele frequencies is reflected in the change in phenotypic frequencies as well, and thus, number of individuals in different classes (eg. spotted fish) change.