Hardy-Weinburg equilibrium?

Question

What are 3 conditions that are necessary for Hardy-Weinberg equilibrium, & provide suitable examples from biology that violate these conditions.

Answer 1

Large populations - Pick an endangered species, say pandas for example

Random breeding - True random breeding is not so easy to maintain. Humans don't truly breed randomly, they tend to prefer their own race.

No migration or selection effects. Again, humans are great for migrating all over the place.

Answer 2

There are actually 5 assumptions that are made for Hardy-Weinberg equilibrium.
a) Mating is random.
b) Population of infinite size.
c) No migration
d) No mutation
e) No selection

Suitable examples from biology that violate these conditions:
a) Obviously selection can occur in mating. Females or males might prefer a certain phenotype. In peacocks, for example, females prefer males with the most flamboyant tails.
b) Obviously no population is of infinite size. The problem with smaller populations is that you have genetic drift. A man named Motoo Kimura in 1968 proposed the Neutral Theory of Molecular Evolution. It shows how, in populations, certain alleles can become "fixed". This is due to random sampling and finite populations. You can look this up if you like.
c) If you have migration, either into or out of the population, you change the frequency of the alleles, and therefore you disrupt the equlibrium.
d) If you have mutations, obviously you add new versions of the genes, which of course would add new factors to the equation.
e) If one of the alleles recessive and is lethal when the organism is homozygote for it, then that would be considered "selection". Also, if you had for example two alleles in flies, one that didn't permit them to fly when the fly was homozygote for it for example, obviously those flies would have a much higher chance of dying.

Hope this helped.
-The Mad Scientist