Final answer:
Options 1, 2, and 3 (a high average excess of fitness for an allele, negative frequency-dependent selection, and balancing selection) all contribute to maintaining genetic diversity within populations. Therefore, none of these scenarios will reduce genetic diversity by eliminating alleles. Therefore, none of these scenarios
Step-by-step explanation:
In the context of maintaining genetic diversity in populations, the options provided are mechanisms that can influence allele frequencies and genotype frequencies within a gene pool. To answer the student's question:
- A high average excess of fitness for an allele typically means that the allele contributes positively to the reproductive success of individuals, thereby being maintained or even increasing in frequency within the population.
- Negative frequency-dependent selection maintains genetic diversity by favoring phenotypes that are rare within the population. This type of selection actually encourages diversity by ensuring that uncommon alleles remain in the gene pool.
- Balancing selection, which includes mechanisms like heterozygote advantage and frequency-dependent selection, maintains multiple alleles at higher frequencies in the population than would be expected by chance alone.
Given these points, the correct answer is that all of the above scenarios do maintain genetic diversity in populations. Thus, the scenarios listed in options 1, 2, and 3 do not reduce genetic diversity by eliminating alleles; rather, they are mechanisms that help preserve or even enhance diversity within a population's gene pool. Therefore, none of these scenarios