Genetic differentiation in populations of the freshwater amphipod \u3cem\u3eGammarus minus\u3c/em\u3e Say in a karst area

The genetic makeup of populations in a particular geographic area should conform, in part, to environmental structure. Three polymorphic enzyme loci in the amphipod Gammarus minus are geographically differentiated in gene frequencies in the mid-Appalachian Mountains of the eastern United States, and genetic breaks usually coincide with topographical features and stream divides. Areas with well integrated drainage systems have a high degree of genetic uniformity