Hardy-Weinberg equilibrium

Question 1

Define Hardy-Weinberg equilibrium

Answer 1

In an “ideal” population allele frequencies do not change – that is, they are at “equilibrium” from generation to generation, unless some force (such as selection) acts on them.

Question 2

Define freely-interbreeding

Answer 2

each individual has an equal likelihood of mating with each potential mate

Question 3

Define no migration

Answer 3

no genes migrating out or entering the population from outside.

Question 4

Name and describe the 5 equilibrium conditions

Answer 4

1) No selection - if selection is alloed, allele frequencies can change. When populations deviate from the expectation that its allele frequencies should remain constant, selection is the most common explanation for why evolution is occurring within that population. Importantly though, it is not the only possible explanation.
2) A large population - Theoretically, a population must be infinitely large for equilibrium truly to appy. In real life this condition is never met, of course, though many populations are large enough that the violation isn’t significant. Small populations (for instance dozens or hundreds of individuals) are subject to random fluctuations in allele frequencies that can be big in small populations and big in small populations.
3) Freely-interbreeding - If one type of individual has more or fewer opportunites to mate than other types have, the result will be that one type will propagate more rapidly than the other. In this case, evolution can occur, even without selection. Many populations do show essentially random mating, but important non-random patterns are seen often enough that you should be alert for them.
4) No migration - Individuals who leave a population take their genes with them.
5) Insignificant mutation rate - Mutation generates new alleles. If a particular gene mutates often enough, it will subtract certain alleles (the ones present before the mutations) from the population while adding other aleles ( the ones resulting from mutation). If mutation is allowed, it will disturb Hardy-Weinberg equilibrium.