A phylogeographic perspective on endemism in the Alexander Archipelago of southeast Alaska

Conservation plans for the North Pacific Coast are beginning to acknowledge that the old-growth forests remaining on the extensive archipelagos of the region may require a new management paradigm. Extensive timber harvesting activities on these islands may impact wildlife populations and be particul arly detrimental to the large number of endemics. Because insular biotas ha ve suffered a disproportionate number of documented extinctions worldwide, the documentation of taxonomic validity and spatial distribution of endemic s should be a priority for management efforts. To date, few North Pacific c oastal endemics have been reevaluated since their original descriptions. Th is study provides an independent view of endemism in the Alexander Archipel ago of southeast Alaska through a phylogeographic assessment of eight speci es of mammals (Sorex monticolus, Glaucomys sabrinus, Microtus longicaudus, Clethrionomys rutilus, Clethrionomys gapperi, Martes americana, Mustela erm inea, Ursus americanus). The molecular data (mitochondrial sequence variati on of the cytochrome b gene) suggest a dynamic history of faunal interchang e in the region. While some purported endemics show minimal levels of genet ic divergence from other conspecific populations, other taxa appear to be m ore divergent than recognized by current taxonomy. Some species in the regi on are comprised of multiple clades or evolutionarily significant units. Th ese reciprocally monophyletic lineages may be the result of multiple Holoce ne invasions (neoendemics) or they may have persisted in refugia (paleoende mics) in the region during Pleistocene glacial advances. This emerging hist orical perspective should have direct implications for the management of th ese endemic taxa. (C) 2000 Elsevier Science Ltd. All rights reserved.