Selection that maintains certain phenotype by selecting against deviations from it.

Selection that maintains certain phenotype by selecting against deviations from it.

• A. Stabilizing selection
• B. Gene flow
• C. Inbreeding
• D. Genetic bottleneck

Answer: (A)

Stabilizing selection is the evolutionary process that maintains a specific phenotype by selecting against individuals with extreme deviations from the common form. In a stable environment where the optimal value doesn’t change, those with average traits have higher fitness, so the population stays centered around that middle phenotype and variation is reduced. For example, very low or very high birth weights in humans are linked to higher mortality, so intermediate birth weight is favored. Gene flow involves movement of alleles between populations, which can alter trait frequencies but doesn’t inherently enforce keeping a single phenotype by penalizing departures from it. Inbreeding increases homozygosity and can expose deleterious traits, rather than specifically maintaining a midpoint phenotype. A genetic bottleneck reduces genetic diversity due to a drastic population drop, changing allele frequencies but not by actively selecting against deviations from a maintained optimum phenotype.

Stabilizing selection is the evolutionary process that maintains a specific phenotype by selecting against individuals with extreme deviations from the common form. In a stable environment where the optimal value doesn’t change, those with average traits have higher fitness, so the population stays centered around that middle phenotype and variation is reduced. For example, very low or very high birth weights in humans are linked to higher mortality, so intermediate birth weight is favored.

Gene flow involves movement of alleles between populations, which can alter trait frequencies but doesn’t inherently enforce keeping a single phenotype by penalizing departures from it. Inbreeding increases homozygosity and can expose deleterious traits, rather than specifically maintaining a midpoint phenotype. A genetic bottleneck reduces genetic diversity due to a drastic population drop, changing allele frequencies but not by actively selecting against deviations from a maintained optimum phenotype.