Which assumption of Hardy-Weinberg would be violated with a large population of fish where females mate with males based on size.
A large population size (i.e. minimal genetic drift)
B random mating
C no gene flow
D no selection
The correct answer and explanation is:
The correct answer is B random mating.
Explanation:
The Hardy-Weinberg principle relies on several key assumptions for a population to maintain genetic equilibrium over generations. These assumptions include a large population size, random mating, no gene flow, no mutation, and no natural selection.
In the scenario where females in a large fish population choose mates based on size, the assumption of random mating is violated. Random mating means that all individuals have an equal chance to mate with any other individual of the opposite sex, regardless of their traits. When mating is non-random and based on a specific characteristic like size, certain alleles associated with size will become more common in the next generation.
Because females prefer males of a particular size, alleles linked to that size trait will be selected for, creating a non-random pattern of mating. This can change allele frequencies because certain genotypes will be favored for reproduction while others will be less likely to pass on their alleles. This process is a form of sexual selection, a type of natural selection where mate choice affects which alleles are passed on.
The other assumptions in the question do not apply as directly. A large population size minimizes genetic drift, so assumption A is not violated here. No gene flow (assumption C) means no migration in or out of the population, which is not mentioned as an issue in this case. No selection (assumption D) means no differences in survival or reproduction, but here selection occurs through mate choice, a type of sexual selection, which is a form of selection violating assumption D. However, since the question focuses on mating behavior, the direct violation is random mating.
In summary, female preference for males based on size means mating is non-random, violating the random mating assumption of Hardy-Weinberg equilibrium. This non-random mating can shift allele frequencies and prevent the population from remaining in genetic equilibrium.