The 'central-marginal’, 'southern richness and northern purity' or 'leading-edge vs. In a majority of organisms, genetic diversity is unevenly distributed within the range of a species. If this decline happens, it will greatly impoverish the genetic, phylogeographic and phylogenetic diversity of Scots pine, that may ultimately affect adaptive potential of the species. By the end of 2080, approximately one-third of the current distribution of Scots pine in Europe might be lost, with southern stands being most affected 5, 6. In the South Caucasus and Asia Minor Scots pine is a Tertiary relic with a patchy distribution in mountainous areas separated from the current main boreal range by a distributional gap of over 1,000 km. Scots pine ( Pinus sylvestris L.) is the most widely distributed pine species, yet its occurrence is seriously threatened by climate change, especially in the isolated and relic populations at the southern fringes of its range 5, 6. All these facets of genetic biodiversity should be more explicitly embodied in the conservation priorities that have been recently articulated by the scientific community 2, 4. Three perspectives of biodiversity that mirror the evolutionary legacy of the species are genetic diversity (neutral and adaptive DNA polymorphisms), phylogeographic diversity (intraspecific evolutionary lineages) and phylogenetic diversity (intraspecies taxonomic units, e.g. However, the genetic components of our trees should be a conservation priority as well 2, 3. Since the beginning of the industrial era we have lost 32% of the world’s forest, and over 8,000 of the world’s 60,065 tree species are threatened with extinction 1. By threatening the stability of the forest ecosystems, this would dramatically affect the biodiversity of the Caucasus hot-spot. From our predictions, over 90% of the current distribution of Scots pine may be lost in this century. However, the current genetic resources of Scots pine are under high pressure from climate change. Scots pine currently grows under a broad spectrum of climatic conditions in the Caucasus, which implies high adaptive potential in the past. We found that the high genetic variability of the Caucasian populations mirrors a complex glacial and postglacial history that had a unique evolutionary trajectory compared to the main range in Europe. We explored demographic and biogeographical processes that shaped the genetic diversity of Scots pine in the Caucasus ecoregion and its probable future distribution under different climate scenarios.
Pine forests are an important reservoir of biodiversity and endemism in this region. A significant part of its range is located in the Caucasus, a global hot-spot of diversity. Scots pine is one of the most widely occurring pines, but future projections suggest a large reduction in its range, mostly at the southern European limits.