 Through genetic observations of diverse regional "P. dominula" populations, an allelic richness and distribution of private alleles was shown in the introduced population, as well as the oldest population (Massachusetts) had the lowest level of genetic variation.Various dispersion mechanisms existed amongst the "P. dominula" species and its origin might not be confined to a single regional area.Furthermore, the genetics of Southern Californian population differed from those of both Eastern and Northern California, suggesting the source of the Southern Californian population may be from either an unsampled area with the introduced range or from a different geographic area from within the native range.