Genetic variation in a semi-natural Drosophila melanogaster population after a bottleneck II. The relative fitnesses of second chromosomes

A semi-natural Drosophila melanogaster population was twice forced through a genetic bottleneck and allowed to recover naturally. In one case additional genetic variation was introduced to the recovering population. Variation in chromosomal fitness was drastically reduced by both bottlenecks but actual fitness values were greatly influenced by the founder effect. This variation reappeared rapidly at first and then gradually reverted to pre-bottleneck levels. However, there were more low-fitness and fewer high-fitness chromosomes than before the first bottleneck. Additional introduced variation had a negligible effect.