Genetic subdivision of Roe’s abalone, Haliotis roei Grey (Mollusca : Gastropoda), in south-western Australia

Abstract

Starch-gel electrophoresis was used to investigate population structure of the commercially and recreationally exploited abalone, Haliotis roei. The standardized variance in allelic frequencies among 10 sites in south-western Australia indicated relatively high levels of gene flow across the 3000 km range sampled (mean F_ST 0.009). Sites showed no striking geographic trends in allelic frequencies or apparent clustering, on the basis of multidimensional scaling of G_ST as a measure of genetic dissimilarity. A population structure of isolation-by-distance was evident when pairwise measures of G_ST were related to geographic distance (r = 0.45, P <0.001). This relationship was evident beneath relatively high levels of variability among pairwise comparisons of G_ST for sites separated by small distances. The area of complete genetic mixing, or neighbourhood size, was estimated to be less than the distance between the two nearest sites, or 13 km. The apparent contradiction between relatively high levels of gene flow across the species’ distribution, as indicated by a low average F_ST, and substantial heterogeneity between sites separated by 10s of kilometres, is discussed in the context of the species’ biology, and management of the fishery.