Phylogeographic and demographic responses of Eurasian moose to climate change since the Late Pleistocene.

Large, cold-adapted ungulates are particularly sensitive to environmental changes and human pressure. Despite a decline in its geographic range and population size, the moose (Alces alces) remains one of the few extant representatives of Eurasian megafauna. We analysed the complete mitochondrial genomes (mtDNA) of 95 subfossil and 137 modern Eurasian moose specimens in order to assess how genetic diversity, effective population size (Nef), and phylogeographic patterns of the species have changed over the last 50,000 years in response to climatic oscillations and human impact. The European and Asiatic-American moose mtDNA lineages diverged approximately 100,000 years BP, occurring in regions with different environmental conditions. All extant mtDNA groups of the Eurasian moose originated before the Last Glacial Maximum (LGM), and subsequently diversified into several subgroups. Bayesian coalescent analyses indicate that Nef was lowest immediately after the LGM, and increased to a maximum during the Middle Holocene. Following this peak, Nef declined towards the present day, decreasing by approximately half in the Asiatic-American lineage and fourfold in the European lineage. The Central European group experienced the strongest range contraction, while the Eastern group remained largely stable and the Western group shifted geographically. The Nef in the Western group fluctuated the least, while that in the Central and Eastern groups declined substantially from the mid-Holocene. Although moose are cold-adapted and sensitive to high temperatures, the most significant factor contributing to the decline of their Nef during the Holocene was likely human impact (overhunting, habitat degradation) rather than climate warming.