Abstract
We investigated the genetic and morphological status of an endemic subspecies of deer mice ( Peromyscus maniculatus anacapae ) on Anacapa Island of California through mitochondrial DNA (mtDNA) analysis, morphometric discriminant function analysis, and population viability analysis. We sought to assist the development of a management plan that may include captive breeding, reintroduction, or translocation of mice following eradication of introduced rats. The genetic and morphological data were used to investigate whether the subspecies or populations on each of the three islets of Anacapa represent evolutionarily significant units for conservation. The status of the East Anacapa population was of particular concern because deer mice have recently been caught there following more than 15 years of no records of deer mice. Sequences of the mtDNA cytochrome oxidase c subunit II gene (COII ) indicated that the Anacapa subspecies had unique haplotypes not found on neighboring islands or the mainland and thus represents a distinct unit for conservation. Further, one of these haplotypes was shared among the islets, including most of the East Anacapa mice, suggesting that the East Anacapa population had either recovered from a severe bottleneck or had been recolonized by P. m. anacapae , but that it was not derived from other subspecies. Discriminant function analysis of morphological data also supported classification of the East Anacapa mice as P. m. anacapae . The mitochondrial mtDNA sequence data yielded estimates of two to seven migrants per generation among the Anacapa islets, suggesting a functioning metapopulation. Incorporating these data and information available on the life history and demographics of deer mice, we used a novel type of population viability analysis to develop a captive breeding and reintroduction plan for Anacapa deer mice should they be eradicated along with the rats. A sine wave was incorporated into the population viability analysis to simulate population size cyclicity. Our study provides baseline information needed for developing a comprehensive conservation and management plan for a threatened island endemic.