The effects of population bottlenecks on multilocus DNA variation in robins

Abstract

The effects of bottlenecks on genetic variation in two wild populations of New Zealand robins (Petroica australis australis) were examined using multilocus minisatellite DNA probes. In each case the size and timing of the bottlenecks were known, together with the location of the source populations. The two founder events occurred in 1973 and both involved five or fewer individuals. Parameters of multilocus DNA profile variation, specifically average percent difference (APD), heterozygosity, numbers of polymorphic loci, and numbers of novel restriction fragments present, were used to measure levels of minisatellite DNA variation in the two sets of source end translocated robin populations. New statistical methods are described that test the significance between the APDs of source and bottlenecked populations. An overall trend toward reductions in minisatellite DNA variation through bottleneck events was observed. However, despite establishment from only one or two founding pairs, moderate levels of variation were maintained in both bottlenecked populations. These results indicate that catastrophic losses of multilocus DNA variation, like single- locus variation, should not be regarded as an inevitable consequence of founder events and population bottlenecks.