What does population bottleneck refer to in genetics?

Population bottleneck in genetics refers to a sharp reduction in population size due to environmental events such as natural disasters, disease outbreaks, or human activities. This phenomenon results in a significant decline in genetic diversity because only a small number of individuals survive and reproduce after the bottleneck event. The decreased population size can lead to a loss of alleles and increased inbreeding, which can affect the overall adaptability and resilience of the population to future changes in the environment.

In contrast, an increase in genetic diversity would suggest that more alleles are contributing to the gene pool, which is not the case in a bottleneck scenario. A gradual reduction in population size over generations implies a slow decline, which does not adequately capture the sudden and dramatic nature of a bottleneck. Finally, a sustained period of population growth contradicts the concept of a bottleneck, as a bottleneck entails a decrease in population size rather than an increase.