Final answer:
The allele frequencies of a favored allele are expected to rise under selection pressures, with the rate of increase being higher when the selection intensity is greater.
Step-by-step explanation:
Under varying selection intensities, we would expect the allele frequencies of the favored allele to rise, with a greater rate at a greater selection intensity. When an allele confers a phenotype that increases an organism's evolutionary fitness, it is more likely to be passed on to subsequent generations. Consequently, the allele frequency increases. This phenomenon is a fundamental principle of adaptive evolution, where beneficial alleles increase in frequency while deleterious alleles decrease due to selection pressures.
For example, the observation of changes in wing coloration in the peppered moth is a classic case that demonstrates how intense selection pressure, such as industrial soot in this case, can rapidly shift allele frequencies. More intense selection results in a faster change in allele frequency. We see this in population genetics studies where allele A, being more advantageous than allele B, increases in frequency due to natural selection.
The rate of increase is proportional to the intensity of the selection pressure; meaning that if the selection pressure is strong and consistent across generations, the favored allele may become fixed in the population. Conversely, at lower selection intensities, the change in allele frequency occurs at a slower pace.