The most likely reasons for the reduction of gene pools in small populations compared to larger populations are inbreeding and bottleneck events. These factors can lead to a decrease in genetic variation within the population, resulting in a smaller gene pool. Inbreeding can reduce the genetic diversity by increasing the likelihood of individuals inheriting harmful genetic mutations. Bottleneck events can occur when a large portion of the population is killed off, leaving only a small and less diverse gene pool to repopulate. Lack of advantageous traits and lack of suitable mates could also contribute to reduced genetic diversity in small populations, but are less likely to be the primary causes.
