The Late Quaternary biogeographic histories of some Great Basin mammals (western USA)

The Great Basin of and western North America provides one of the most detailed late Pleistocene and Holocene mammal records available for any part of the world, though the record is by far strongest for small mammals. Of the 35 genera of now-extinct North American Pleistocene mammals, 19 are known to have occurred in the Great Basin, a list that is likely to be complete or nearly so. Of these 19, seven can be shown to have survived beyond 12,000 radiocarbon years ago, a proportion similar to that for North America as a whole. Horses, camels, mammoth, and helmeted musk-oxen appear to have been the most abundant of these genera. Pygmy rabbits (Brachylagus idahoensis), yellow-bellied marmots (Marmota flaviventris), and bushy-tailed woodrats (Neotoma cinerea) declined in abundance at the end of the Pleistocene, at about the same time as populations south of their current and western distributional boundary were extirpated. Subsequent declines occurred during the hot/dry middle Holocene. Pygmy rabbits also declined as modern pinyon-juniper woodlands developed across the Great Basin. The Snake Range of eastern Nevada has seen the late Pleistocene or Holocene extinction of both northern pocket gophers (Thomomys talpoides) and pikas (Ochotona princeps). Coupled with the rarity of yellow-bellied marmots here, these histories make the Snake Range a biogeographic oddity. These and other Great Basin mammal histories provide significant insights into the possible responses of Great Basin small mammals to global warming. (c) 2006 Elsevier Ltd. All rights reserved.