AN ICE-AGE REFUGIUM FOR LARGE MAMMALS IN THE ALEXANDER ARCHIPELAGO, SOUTHEASTERN ALASKA

Genetic and paleontological evidence are combining to provide a new an d surprising picture of mammalian biogeography in southeastern Alaska. Prior to our study, the brown and black bears of the Alexander Archip elago were considered postglacial immigrants that never had overlappin g ranges. Vertebrate fossils from caves on Prince of Wales Island now demonstrate that brown and black bears coexisted there (and even inhab ited the same caves) both before and after the last glaciation. Differ ences in mtDNA sequences suggest that living brown bears of the Alexan der Archipelago comprise a distinct clade and are more closely related to polar bears than to their mainland conspecifics. We conclude that brown bears, and perhaps other large mammals, have continuously inhabi ted the archipelago for at least 40,000 yr and that habitable refugia were therefore available throughout the last glaciation. (C) 1996 Univ ersity of Washington.