What does the bottleneck effect refer to in population genetics?

The bottleneck effect refers to a significant reduction in the size of a population due to environmental events, such as natural disasters, disease outbreaks, or human activities. This sudden decrease in population size can lead to a loss of genetic diversity, as only a small number of individuals contribute to the gene pool of future generations.

In this context, when large numbers of the population are removed in a few generations, the surviving population may not represent the genetic diversity of the original population. This event creates a "bottleneck," resulting in a limited genetic variation that can affect the adaptability of the population in the long term. The consequences of the bottleneck effect can include increased susceptibility to diseases and reduced ability to adapt to environmental changes, which can have significant implications for the survival of the species.

Other options describe different genetic concepts, such as natural selection or gene flow, but do not capture the essence of the dramatic reduction in population and its effects on genetic diversity represented by the bottleneck effect.