Fine-Grained Spatial Genetic Structure in the Bivalve Gemma gemma from Maine and Virginia (USA), as Revealed by Inter-Simple Sequence Repeat Markers
Gemma gemma is a small ovoviviparous bivalve distributed in shallow sand flats along the North American Atlantic and Gulf of Mexico coasts. Genetic variation in G. gemma was analysed by means of Inter-Simple Sequence Repeats (ISSRs) at the following levels: (i) between localities (Maine and Virginia), (ii) among 10-m-diameter patches within localities, and (iii) within patches. Thirty individuals/patch and three patches/locality were analysed. Individuals were genotyped for 67 ISSR polymorphic loci from five primers. The portion of the genetic variation found between localities (2%) was small compared to that found either among patches within localities (37%) or within patches (61%). ISSRs in G. gemma allowed the detection of significant differentiation at individual and patch levels. By contrast, a low degree of genetic variability was found between localities. The small-scale genetic heterogeneity does not follow a simple, consistent pattern. Our results contrast with the generally accepted rule that aplanic species are locally homogeneous and globally heterogeneous and teleplanic species are the inverse.
Casu, Marco, et al. "Fine-Grained Spatial Genetic Structure in the Bivalve Gemma gemma from Maine and Virginia (USA), as Revealed by Inter-Simple Sequence Repeat Markers," Journal of Experimental Marine Biology and Ecology 325.1 (November 2005), 46-54.