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

Translocation of species to new locations is a widespread procedure in conservationbiology. Conventional wisdom suggests using large numbers of donor stockfrom sites as close and as ecologically similar to the recipient location as possibleto minimise risks from maladaptation and outbreeding depression. Here, wecompare translocation success to a common receptor site of animals from a largebut distant population with those from smaller proximal populations. Commontoads (Bufo bufo) from a site far from the recipient locality and with very differenthabitat rapidly established a new population where three attempts with localanimals failed. After 10 years, the new population retained allele frequency distributionsat microsatellite loci almost the same as the donor site, whereas majorhistocompatibility complex allele frequencies changed to resemble local ones.Variations in phenology and climate could not readily explain the success of thedistant translocation source. We postulate that success was due to the very largesize of the donor population compared with local sources, implying that highlevels of mean fitness or adaptive variation can be more important than localfactors when considering translocations, at least in some circumstances.