Final answer:
In a population of 500 frogs with 350 displaying a dominant trait of yellow skin spots, it is estimated that the closest number of heterozygous frogs (Aa) would be 252, based on Hardy-Weinberg equilibrium proportions.
Step-by-step explanation:
The question pertains to genetics in a population of frogs in a pond, specifically dealing with the inheritance of yellow skin spots as a dominant trait. Given that there are 500 frogs and 350 of these have yellow spots, we can infer that the remaining 150 frogs do not have yellow spots (are homozygous recessive, aa). Assuming the simplest case of Hardy-Weinberg equilibrium, we would expect to see a 3:1 ratio of dominant to recessive phenotypes in a large, randomly mating population if there is no selection, mutation, or migration.
To calculate the expected number of heterozygotes (Aa), you could take the square root of the product of the number of homozygous dominant (AA) and homozygous recessive (aa) individuals. However, without knowing the exact number of AA individuals, we cannot perform this calculation directly. Nonetheless, a rough estimate assuming Hardy-Weinberg proportions would be roughly twice the number of aa individuals for Aa individuals since the ratio of aa to Aa is approximately 1:2.
Since there are 150 frogs that do not show the dominant trait, and if we apply that estimate, about 300 frogs would be heterozygous Aa. However, given the options provided, the closest to our estimate would be 252 frogs. Thus, the answer in a typical Mendelian fashion would be d. 252.