Should endemism be a focus of conservation efforts along the North PacificCoast of North America?

Most documented extinctions of vertebrates in the last 400 years have been island endemics. In this paper, we focus on the need to develop a historica l framework to establish conservation priorities for insular faunas and, in particular, to test the validity of nominal endemics. We use the example o f the islands of the North Pacific Coast (NPC) of North America, a region t hat includes approximately one-half of all mammals endemic to North America n islands north of Mexico (seven species and 67 subspecies). Few of these e ndemics have been re-evaluated since their original descriptions, although many of these islands have been heavily impacted by habitat conversion, spe cies introductions, over-exploitation, and secondary ripple effects. Eviden ce from molecular genetics and paleontology suggests that many taxa arrived in the region since the last glacial advance. Some of these nominal endemi cs show minimal differentiation, while others comprise multiple evolutionar y lineages. The NPC may also have played an important role in the in situ d iversification of some taxa (paleoendemics) during the Pleistocene. Evidenc e, such as new fossil discoveries and numerous described endemics, lends su pport for refugia hypotheses. However, these ideas cannot be tested until a better understanding of geographic variation and the evolutionary relation ships of the fauna and flora of the North Pacific Coast is developed. This framework would provide significant insight into the dynamic biogeographic history of the region and help prioritize conservation efforts. (C) 2000 El sevier Science Ltd. All rights reserved.