The scale of genetic differentiation in Leptosynapta clarki (Heding), an infaunal brooding holothuroid

Abstract

The direct developmental mode and sedentary habit of Leptosynapta clarki (Heding), an infaunal, brooding holothuroid, suggest that this species has limited dispersal capabilities. Using starch gel electrophoresis, we estimated allele frequencies at two polymorphic enzyme loci in three populations to look for consequences of limited dispersal on genetic structure of populations. Genetic composition within populations was characterized by linkage equilibrium and heterozygote frequencies which equalled or exceeded Hardy-Weinberg expectations, indicating that inbreeding does not occur and self-fertilization is not a common reproductive mode in this species. Comparisons among populations separated by 11–24 km showed significant differences in allele frequencies at both loci, indicating that populations are genetically differentiated. These differences are probably due to genetic drift or local adaptation occurring in the absence of high levels of gene flow.