Extremely low genetic variation in endangered Tatra chamois and evidence for hybridization with an introduced Alpine population

Abstract

The Tatra chamois (Rupicapra rupicapra tatrica) is an endangered endemic subspecies living exclusively in the Tatra Mountains (Slovakia and southern Poland). In order to protect this evolutionary significant unit, a back-up population was established in the nearby Low Tatra Mts. in the 1970s. Before the subspecific status of Tatra chamois had been recognised, however, non-native Alpine chamois (R. r. rupicapra) were introduced to two adjacent mountain ranges. In order to assess their present conservation status, therefore, we undertook a thorough genetic analysis of all Slovak chamois populations (n = 363; 20 microsatellites, SRY gene, MHC class II DRB gene and mtDNA). We found low genetic variation and a high level of inbreeding in all populations, the least variable being the native Tatra chamois population (only one MHC allele), which we ascribe primarily to population bottlenecks. Introduced Alpine chamois showed greater variation, despite originating from few founders. One population, however, founded by just six individuals, also showed highest inbreeding. Male-biased introgressive hybridization between the back-up Low Tatra population and both introduced Alpine populations was detected using several approaches, with up to 19 % of the genome introgressed from Alpine chamois. Such hybridization can be viewed ambiguously as regards conservation in that, though it disrupts the integrity of the unique Tatra chamois genome in the back-up population it also improves its very low genetic variation and decreases inbreeding level, with no obvious signs of outbreeding depression.