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Island populations may have a higher extinction risk due to reduced genetic diversity and need to be managed effectively in order to reduce the risk of biodiversity loss. The Eurasian red squirrels (Sciurus vulgaris) in the south of England only survive on three islands (the Isle of Wight, Brownsea and Furzey islands), with the Isle of Wight harbouring the largest population in the region. Fourteen microsatellites were used to determine the genetic structure of red squirrel populations on the Isle of Wight, as well as their relatedness to other populations of the species. Our results demonstrated that squirrels on these islands were less genetically diverse than those in Continental mainland populations, as would be expected. It also confirmed previous results from mitochondrial DNA which indicated that the squirrels on the Isle of Wight were relatively closely related to Brownsea island squirrels in the south of England. Importantly, our findings showed that genetic mixing between squirrels in the east and west of the Isle of Wight was very limited. Given the potential deleterious effects of small population size on genetic health, landscape management to encourage dispersal of squirrels between these populations should be a priority. [ABSTRACT FROM AUTHOR]

Climate change accelerates biodiversity alterations in northern ecosystems. A prevalent example is that tundra regions are invaded by boreal species. This impacts negatively on native species through competition, predation and transmission of zoonoses. Scandinavian red foxes ( Vulpes vulpes) have emerged into the tundra and have altered the structure and function of the tundra community. For instance, they threaten persistence of the endangered Swedish Arctic fox ( Vulpes lagopus). County board administrations implement control of the tundra red foxes, but little is known about the underlying expansion dynamics. A broad-scale study revealed high connectivity where northern areas were supplemented with red foxes from surrounding population. However, red fox expansion is most prevalent in tundra regions and the fine-scaled expansion dynamics in these areas have not yet been disseminated. With the aim of identifying the invasive pathways of tundra red foxes, we present microsatellite data for 205 Swedish red foxes and mitochondrial sequence variation in 102 foxes sampled across the historical boreo-nemoral distribution and recently colonized tundra regions. Genetic structuring was low with high levels of ongoing, asymmetric dispersal from surrounding boreal zones into tundra habitats causing high genetic admixture. In both tundra and boreo-nemoral regions, inter-individual relatedness decreased with increasing geographic distance and data suggests male-biased dispersal patterns. Overall, fine-scaled expansion patterns were affected by multiple factors and we discuss its implications for future red fox management. [ABSTRACT FROM AUTHOR]

Introgression and admixture from domestic or foreign conspecifics into wild populations are of great concern in wildlife conservation. The issue is of particular interest in ungulates where translocations and re-introductions have been common practice. In Europe, the only large remaining wild populations of reindeer ( Rangifer tarandus L.) are found in the mountainous habitats of southern Norway. These populations have during the last centuries been exposed to extensive habitat modifications and periods of contact with domestic reindeer. Through analyses of ancient and extant mitochondrial DNA (mtDNA) we document extensive intra- and inter-population genetic changes during the last millennium. Our data indicate population reduction within a short time interval during the 11th-12th century during a period when mass trapping of reindeer was common. Significant differentiation between the ancient herds suggests an ancient genetic structuring of the reindeer herds in southern Norway, although not as strong as between modern herds. Two different mtDNA lineages characterized the ancient herds. A Bayesian approach to reconstruct the recent evolutionary history suggests that the reindeer herds in southern Norway originate from two populations separated in different refugia during the last glacial period. The presence of two additional extant lineages, characteristic of domestic herds, suggests substantial introgression into the native wild reindeer. The putatively different refugial origins of the lineages represented by the extant herds in Rondane/Dovre, Hardangervidda and those with a mainly domestic origin may well reflect different adaptations to environmental conditions, including degree of human interference. Further research on this issue would provide important insights for conservation priorities and a sustainable and flexible management strategy for the remaining wild reindeer herds in the Scandinavian mountains. [ABSTRACT FROM AUTHOR]