Reduced genetic variation in insular northern flying squirrels (Glaucomys sabrinus) along the North Pacific Coast

Nearshore oceanic archipelagos are natural laboratories that could provide valuable insight into the role of evolutionary processes such as founder ef fects and incipient speciation in biotic conservation. The Alexander Archip elago of Southeast Alaska is an example of such a complex, yet few biologic al investigations have been conducted. For the past 50 years, the region ha s experienced intense anthropogenic disturbances (particularly timber harve sting), causing habitat fragmentation and potential disruption of biotic co mmunities. As part of a series of studies of mammals endemic to Southeast A laska, we examined mitochondrial DNA sequences from 118 flying squirrels to investigate genetic diversity across Southeast Alaska. Mitochondrial seque nce divergence corroborates the subspecific designation of the endemic Prin ce of Wales flying squirrel (Glaucomys sabrinus griseifrons). This island l ineage exhibits severely reduced genetic variation and may be the result of an early Holocene founder event. Nearly all of the animals we examined on Prince of Wales Island and ten islands to the west had identical cytochrome b (52 of 53) and control region (21 of 21) sequences. In contrast, substan tial polymorphism and little genetic structuring were found in comparable p opulations on the mainland of Southeast and Interior Alaska. Because flying squirrels in the Pacific Northwest are associated with old-growth forest, forest-use plans should aim to conserve this unique lineage of island squir rels.