Late Pleistocene beetle faunas of Beringia: where east met west

Aim To examine the issue of Beringian steppe-tundra from an entomological s tandpoint, using fossil beetle data collected from late Pleistocene sites. Location North-eastern Siberia (Western Beringia), the Bering Land Bridge ( Central Beringia), and Alaska and the Yukon Territory (Eastern Beringia). Methods Analysis of habitat preferences of beetle species found in fossil a ssemblages, leading to classification of major habitat types characterized by the faunal assemblages. Results Fossil beetle assemblages indicative of steppe-rundra are found mai nly in the interior regions of Eastern Beringia, whereas these assemblages dominate nearly all late Pleistocene fossil sites in Western Beringia. East ern Beringian faunas contain a much larger proportion of mesic to hygrophil ous species and very few arid-habitat species. In contrast to this, the hab itat requirements of the Western Beringian faunas are more evenly spread ac ross the moisture spectrum. Main conclusions The taxonomic patterns of the two sets of fossil assemblag es are remarkably different. Eastern Beringian faunal assemblages contain s ubstantial numbers of mesic tundra and riparian rove beetles (Staphylinidae ); this element is almost entirely lacking in the Western Beringian fossil assemblages. Taphonomic bias tends to overemphasize moisture-loving species at the expense of dry, upland species in the fossil record. Both Western a nd Eastern Beringian landscapes undoubtedly contained mosaics of habitats r anging from dry uplands (steppe-tundra) through mesic tundra to bogs and ri parian corridors.