Question

with ____ selection, the frequency of a favored allele will increase as a phenotypic variation becomes more adaptive. directional stabilizing disruptive frequent mutational

Explanation:

• Directional selection: Favors one extreme phenotype. As the favored allele (associated with the adaptive phenotype) is selected for, its frequency increases over time. For example, in an environment where larger beaks in finches are more adaptive (e.g., to crack larger seeds), the allele for larger beaks (a phenotypic variation) will increase in frequency.
• Stabilizing selection: Favors the intermediate phenotype. It reduces phenotypic variation rather than increasing the frequency of a single extreme - it selects against both extreme phenotypes. For example, human birth weight - too low or too high birth weights are less likely to survive, so intermediate birth weights are favored.
• Disruptive selection: Favors both extreme phenotypes. It can lead to a bimodal distribution of phenotypes. For example, in a population of snails, if light - colored snails are camouflaged in the sand and dark - colored snails are camouflaged in the shadows, while intermediate - colored snails are easily spotted by predators.
• Frequent is not a type of natural selection. Natural selection types are based on how they act on phenotypic variation (directional, stabilizing, disruptive).
• Mutational refers to changes in the DNA (mutations) that can provide the raw material for natural selection, but it is not a type of selection itself.

Answer:

directional