Question

Mutations in the GDF9 gene in sheep have been linked to changes in female fecundity. The following are the relative fitnesses of different genotypes in the population:

Relative fitness
+/ - 1
+/ + 0.7
-/ -
0.1
(a) this is an example of heterozygote advantage; genetic variation will be lost over time
(b) this is an example of negative frequency-dependent selection; genetic variation will be lost over time
(c) this is an example heterozygote advantage; genetic variation will be maintained over time
(d) this is an example of negative frequency-dependent selection; genetic variation will be maintained over time

Answer 1

This question deals with the GDF9 gene in sheep and demonstrates heterozygote advantage, where the heterozygous genotype has the highest relative fitness, leading to the maintenance of genetic variation over time.

Step-by-step explanation:

The question involves understanding the consequences of genetic variation on population dynamics due to natural selection and the maintenance of diversity via heterozygote advantage. The relative fitness values provided for the different genotypes of the GDF9 gene in sheep—heterozygotes having the highest fitness (1), followed by homozygotes for the wild type allele (0.7), and homozygotes for the mutant allele having the least fitness (0.1)—demonstrate a clear case of heterozygote advantage. This condition fosters the maintenance of genetic variation within the population over time because the heterozygous individuals have a higher fitness compared to either type of homozygous individuals.

Therefore, the correct answer is that this is an example of heterozygote advantage; genetic variation will be maintained over time (option (c)).