Population genetic structure of the introduced North American population of the hornet, Vespa crabro Germana Christ.

摘要

The European hornet, Vespa crabro was introduced to North America during the mid 19th century, and since that time has spread across the eastern half of the United States and parts of Canada. This study was performed to ascertain some basic aspects of the founding group as well as determine whether the level of variation in this population differs from that of native populations. Using mitochondrial DNA, I investigated the effective population size of the founding group and the probable source of this population. Utilizing nuclear microsatellite DNA, I investigated overall levels of genetic variation in the North American population relative to those of European populations, and characterized the spatial distribution of alleles in North America.;Mitochondrial sequence data revealed that the probable source for the North American population was Germany. The data also suggested that the founding group was small; there was but a single mitochondrial haplotype represented for North America at the three loci investigated (COI, COII and Cytochrome-B). Microsatellite data indicated that North American V. crabro have an exceedingly low level of genetic variation, both overall and when compared with levels of variation found in Europe. Wright's FST values significantly differed between North American and European populations as did numbers of alleles per locus and allele frequencies. Perhaps the most compelling data from this investigation was that, for one locus, there was but a single allele found for all of North America. This confirmed the earlier conclusion from the mitochondrial dataset, that the founding population for North America was small. Finally, my investigation of the spatial distribution of alleles indicated that variation decreases as the population has spread. At each locus, there were fewer alleles detected for each of the subpopulations (Northeast, Southeast, Midwest) moving away from the introduction site. There was also a significant shift in the relative allele frequencies between the Northeast and Midwest subpopulations, indicating a loss of variation. These data represent the first molecular genetic investigation of North American V. crabro. I anticipate that these data will establish a baseline for future studies of this and other introduced social hymenopterans.