Genetic studies of the venerid clam genus Katelysia

摘要

Two samples of Katelysia scalarina, one of K. rhytiphora, and one of K. peronii were compared for 16 allozyme loci. Diagnostic loci were identified, one of which (SOD*) provided unambiguous discrimination of all three clam species. Katelysia rhytiphora and K. peronii were found to be the most similar pair(D = 0.34). Variability levels were high, with average observed heterozygosities per locus ranging from 0.257 to 0.314, and percentage polymorphism from 62.5 to 81.3. Six samples of K. scalarina (three from Tasmania and one each from Victoria, South Australia, and Western Australia), examined for six variable loci, revealed three distinct groups: the three Tasmanian samples; the Victorian and South Australian samples; and the Western Australian sample. Differentiation between the Tasmanian and mainland subpopulations was striking, especially for the PGM* locus. Coastal gene flow mediated by stepping-stone migration between adjacent subpopulations may account for the similarities between subpopulations on the same land mass; whereas, the 10 to 12-day larval period is likely to kinder gene flow across the Bass Strait between Tasmania and the mainland. It is suggested that any future Tasmanian hatchery production should use Tasmanian rather than mainland broodstock, and vice versa, to prevent the introduction to native populations of possibly ill-adapted genotypes.