Project description:Anthropogenic reintroduction can supplement natural recolonization in reestablishing a species' distribution and abundance. However, both reintroductions and recolonizations can give rise to founder effects that reduce genetic diversity and increase inbreeding, potentially causing the accumulation of genetic load and reduced fitness. Most current populations of the endemic high-arctic Svalbard reindeer (Rangifer tarandus platyrhynchus) originate from recent reintroductions or recolonizations following regional extirpations due to past overharvesting. We investigated and compared the genomic consequences of these two paths to reestablishment using whole-genome shotgun sequencing of 100 Svalbard reindeer across their range. We found little admixture between reintroduced and natural populations. Two reintroduced populations, each founded by 12 individuals around four decades (i.e. 8 reindeer generations) ago, formed two distinct genetic clusters. Compared to the source population, these populations showed only small decreases in genome-wide heterozygosity and increases in inbreeding and lengths of runs of homozygosity. In contrast, the two naturally recolonized populations without admixture possessed much lower heterozygosity, higher inbreeding and longer runs of homozygosity, possibly caused by serial population founder effects and/or fewer or more genetically related founders than in the reintroduction events. Naturally recolonized populations can thus be more vulnerable to the accumulation of genetic load than reintroduced populations. This suggests that in some organisms even small-scale reintroduction programs based on genetically diverse source populations can be more effective than natural recolonization in establishing genetically diverse populations. These findings warrant particular attention in the conservation and management of populations and species threatened by habitat fragmentation and loss.
Project description:A small, shed antler fragment of a reindeer from Sjælland, Denmark has been dated to the Mid-Holocene, ca., 4700 cal B.C. Reindeer was an important component of the Lateglacial fauna in Denmark, and the species survived for ca. 1400 years into the Holocene. However, we consider it highly unlikely that this species inhabited Denmark during the Mid-Holocene, when dense forests characterized the vegetation and summer temperatures were somewhat higher than at present. We suggest that the reindeer antler came to Sjælland from Norway or Sweden as a result of trade, perhaps involving flint.
Project description:Pure wild forest reindeer (Rangifer tarandus fennicus) or hybrids? Whole genome sequencing approach to solve the taxonomical status