Donor population size rather than local adaptation can be a key determinant of amphibian translocation success

Abstract

AbstractTranslocation of species to new locations is a widespread procedure in conservation biology. Conventional wisdom suggests using large numbers of donor stock from sites as close and as ecologically similar to the recipient location as possible to minimise risks from maladaptation and outbreeding depression. Here, we compare translocation success to a common receptor site of animals from a large but distant population with those from smaller proximal populations. Common toads (Bufo bufo) from a site far from the recipient locality and with very different habitat rapidly established a new population where three attempts with local animals failed. After 10 years, the new population retained allele frequency distributions at microsatellite loci almost the same as the donor site, whereas major histocompatibility complex allele frequencies changed to resemble local ones. Variations in phenology and climate could not readily explain the success of the distant translocation source. We postulate that success was due to the very large size of the donor population compared with local sources, implying that high levels of mean fitness or adaptive variation can be more important than local factors when considering translocations, at least in some circumstances.