Temporary dramatic reduction in size of a population or species.

Temporary dramatic reduction in size of a population or species.

• A. Genetic bottleneck
• B. Sexual selection
• C. Gene flow
• D. Directional selection

Answer: (A)

A genetic bottleneck describes a temporary dramatic reduction in population size that leads to a loss of genetic diversity. When numbers plummet quickly, only a random subset of the original alleles survives. That amplifies genetic drift and can fix or lose alleles by chance, often resulting in higher relatedness among survivors and potential inbreeding. Even after the population recovers in size, the genetic makeup may remain altered compared to before the bottleneck, which can affect future adaptability. This differs from sexual selection (traits favored by mate choice), gene flow (movement of genes between populations), or directional selection (consistent favoring of one trait), none of which describe a sudden, drastic drop in population size.

A genetic bottleneck describes a temporary dramatic reduction in population size that leads to a loss of genetic diversity. When numbers plummet quickly, only a random subset of the original alleles survives. That amplifies genetic drift and can fix or lose alleles by chance, often resulting in higher relatedness among survivors and potential inbreeding. Even after the population recovers in size, the genetic makeup may remain altered compared to before the bottleneck, which can affect future adaptability. This differs from sexual selection (traits favored by mate choice), gene flow (movement of genes between populations), or directional selection (consistent favoring of one trait), none of which describe a sudden, drastic drop in population size.