ABSTRACT
R. L. Garthwaite Institute of Marine Sciences, University of California, Santa Cruz, Calif., USA; and Osher Foundation Laboratory for Molecular Systematics, California Academy of Sciences, San Francisco, Calif., USA R. Lawson Osher Foundation Laboratory for Molecular Systematics, California Academy of Sciences, San Francisco, Calif., USA; and Leeds City Museum, Natural History Dept., Calverly St., Leeds, UK C. Sassaman Department of Biology, University of California, Riverside, Calif., USA
ABSTRACT
A survey of genetic variation at up to nine enzyme loci in the synanthropic oniscid isopod Armadillidium vulgare (Latreille, 1804) was conducted from 1980 to 1992 using 157 population samples comprising over 10,000 individuals from throughout Europe and North America. Based on analysis of F-statistics, most observed genetic variation in this species in both Europe and North America was found within populations. In Europe, allele frequencies were generally found to be highly variable among populations with large differences occurring over relatively short distances. Northern Europe was found to be substantially different from southern Europe. In contrast, in North America, allele frequencies were found to be more broadly similar with smaller differences among regions. Similarities of allele frequencies among regions of North America and Europe, as measured by F-statistics and allele distributions, were found to correlate with expected similarities based on the history of human colonization of North America by Europeans. However, due to the similarity in climatic and environmental factors between likely European source areas and areas of potential colonization in North America, the observed similarities in allele frequencies would also support a selective interpretation of the data. The patterning of genetic variation in A. vulgare in Europe and North America is discussed in light of selective and historic theories.
