How was genetic diversity transferred with translocations from ex situ to in situ? A case study of the European mink translocation to Hiiumaa Island in Estonia

The European mink (Mustela lutreola) is one of the most threatened small carnivores, listed as Critically Endangered on the IUCN Red List. Tallinn Zoo started a conservation breeding operation in 1980, which in 1992 was shaped into the European mink EEP Program to maintain a demographically and genetically healthy population in captivity. Since 2000, mink have been translocated on a yearly basis from the breeding facility in the zoo to Hiiumaa Island (Estonia) until the formation of the wild island population in 2016. Maintaining a healthy genetic structure in a captive population was a priority, so genetically the least valuable animals, according to calculations made by a population management program, were used for translocation. This study aims to assess the amount of genetic diversity passed from an ex situ population on to the island population. Comparisons of the genetic diversity were made by mitochondrial, microsatellite and nuclear markers. In addition, our results were combined with the pedigree data from the European mink EEP Studbook to further evaluate the flow of genetic diversity from the founder population to the established wild population. According to the findings, the island population's allelic richness was comparable to that of the founder population, and no evidence was found that its genetic structure had diverged from that of the founder population. It seems that the formation of the island population has been a gradual process of no more than the last seven yearly translocations.