Wallace, Lisa , Helenurm, Kaius .
Microsatellite loci reveal population genetic history of Crossosoma californicum (Crossosomataceae), an endemic species of the Channel Islands.
The Channel Islands off the coast of California comprise an archipelago which, despite being geographically close to continental North America, have never been connected to them, and contain a rich flora with many species endemic to one or a few of the islands. Crossosoma californicum (Crossosomataceae) is a deciduous shrub primarily found on San Clemente and Santa Catalina Islands (CA), although it also occurs on Guadalupe Island (Mexico), where it is almost extinct, and the Palos Verdes peninsula (CA), where it is represented by only three, possibly introduced, individuals. Populations on San Clemente Island are widely scattered, range in size from one to only four individuals, and are expected to harbor low levels of genetic variability. Previous studies, in fact, support this prediction as electrophoretic data from 14 allozyme loci indicate very low levels of genetic variation in populations on San Clemente Island. In contrast, populations on Santa Catalina Island are considerably larger, and are therefore expected to be more genetically variable. In the present study we examine population genetic structure in populations of this rare insular species from both San Clemente and Santa Catalina Islands using variation at microsatellite loci. Substantially higher levels of variation were found at microsatellite loci compared to allozyme loci. Additionally, the San Clemente populations, despite being small and scattered, do not appear to be genetically depauperate in comparison to populations from Santa Catalina Island. The level and structure of variation at microsatellite loci will be discussed in the context of the origin of populations on each of the islands and the potential for and patterns of gene flow among populations and between islands, thereby providing a context in which conservation management decisions can be made.
1 - University of South Dakota, Department of Biology, 414 East Clark Street, Vermillion, South Dakota, 57069, USa
Presentation Type: Paper
Location: Peruvian (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 11:15 AM