Non-indigenous introgression into the Norwegian red deer population

Abstract

Rates of introgression from non-indigenous into native populations are increasing worldwide, often as a result of anthropogenic translocation events. In ungulates translocations have been common, especially among deer. European red deer consists of two distinct lineages, one western and one eastern. These probably originate from different glacial refuges, but it is unknown to what extent they hold different adaptations. Here we address dispersal and introgression into the Norwegian mainland population from an introduced island stock consisting of an admixture of both European lineages. The last decade this stock has grown considerably in number and dispersal could be expected to have increased. We therefore used samples separated by a 5 year interval from Otteroya, adjacent mainland areas and a more distant sub-population. Bayesian assignment analysis verified the genetic structure and identified dispersal between the Otteroya stock and the adjacent mainland coastal areas. Three individuals (two newly sampled) with second or third generation non-indigenous origin were found among the adjacent mainland samples (5 and 3 %, respectively). Two individuals with first and second generation mainland-origin were found on Otteroya (old samples). This suggests some non-indigenous introgression from Otteroya into the mainland Norwegian population.