Origins and diversity of the Bering Sea Island fauna: shifting linkages across the northern continents

We synthesize the historical biogeography of non-marine fauna (mammals, birds, fish, non-parasitic and parasitic invertebrates) occurring across Bering Sea islands, considering endemism, species with origins in both North America and Far East Asia, and the impacts of introduced species through the Bering region. Insular communities often constitute assemblages of unique evolutionary lineages that reflect both neutral and selective processes of diversification as a consequence of isolation and through responses to in situ environmental change. However, current knowledge of the basic distribution, ecology, and evolutionary identity of the majority of terrestrial species through the Bering Sea region is still generally lacking. A preponderance of scientific effort associated with these islands has instead focused on conservation and management of marine-associated species and economically viable biological resources. Given the critical role that terrestrial environments play in maintaining evolutionary and ecological linkages between land and sea, a greater understanding of existing biodiversity, and the biological processes that influence community integrity through this remote region is warranted. Resolving responses of resident insular species to rapidly warming Arctic climate and to modern human-associated disturbances provides valuable insight for effective management of future population trajectories and for revealing the dynamics of intra- and inter-specific connectivity across the northern hemisphere and between marine and terrestrial ecosystems. The location of this region at a high-latitude cross-roads has led to a preponderance of island taxa having trans-Beringian distributions. Species associated with the Palearctic or the Nearctic occur across a strong longitudinal gradient, reflecting the role of the Bering Sea as a dispersal filter between mainland areas. Aleutian oceanic islands reflect different biogeographic histories among taxonomic groups from land-bridge islands of the Bering Sea. We discuss evidence of recent biodiversity responses to modern environmental perturbations, including continued colonisations and novel species interactions, and call for increased scientific scrutiny of terrestrial fauna across these remote outposts.