Late Pleistocene beetle faunas of Beringia: where east met west

Aim To examine the issue of Beringian steppe-tundra from an entomological standpoint, 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 assemblages, leading to classification of major habitat types characterized by the faunal assemblages. Results Fossil beetle assemblages indicative of steppe-rundra are found mainly in the interior regions of Eastern Beringia, whereas these assemblages dominate nearly all late Pleistocene fossil sites in Western Beringia. Eastern Beringian faunas contain a much larger proportion of mesic to hygrophilous species and very few arid-habitat species. In contrast to this, the habitat requirements of the Western Beringian faunas are more evenly spread across the moisture spectrum. Main conclusions The taxonomic patterns of the two sets of fossil assemblages are remarkably different. Eastern Beringian faunal assemblages contain substantial 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 and Eastern Beringian landscapes undoubtedly contained mosaics of habitats ranging from dry uplands (steppe-tundra) through mesic tundra to bogs and riparian corridors.