Low genetic diversity in an endangered species: recent or historic pattern?

Examining patterns of genetic diversity has become an integral component of many management plans concerning endangered species, yet interpreting the processes underlying such patterns remains challenging. We demonstrate low genetic diversity in a critically endangered small mammal population. A com mon interpretation of this pattern would be that it is the result of a know n, recent decline in this population. We test this interpretation and find it to be incorrect. Instead, by using museum voucher specimens, we show tha t the pattern of low genetic diversity is historical. This study demonstrat es the importance of choosing appropriate reference groups by which to inte rpret modern levels of genetic diversity in endangered species. We conclude that analysis of archival specimens may be essential in cases where geneti c diversity is driving conservation management decisions because it may all ow us to distinguish the effects of low genetic diversity from the process of losing diversity. We recognize that this approach can be limited due to several sampling issues: archival material may not be available, statistica l power needs to be evaluated, sample sizes and sequence lengths may be sub optimal due to intrinsic difficulties associated with amplification of degr aded DNA. These issues are discussed and possible solutions identified. (C) 2001 Elsevier Science Ltd. All rights reserved.