Genetic heterogeneity in natural beds of the razor clamEnsis siliquarevealed by microsatellites

Abstract

The aim of this study was to analyse the genetic diversity and population structure in the razor clamEnsis siliquaalong the European Atlantic coast taking into account their recent history of exploitation and the ‘Prestige' oil spill. To this end we examined the genetic variability of microsatellite markers in 211 razor clams from five populations in Ireland, Portugal and Spain. Microsatellite data revealed a low genetic differentiation between the Spanish and Portuguese populations (FST = 0–0.032) and a moderate differentiation of these populations and the Irish samples (FST = 0.071–0.100). Although we observed changes in genetic diversity in accordance with the level of exploitation and the distribution of the oil spill, these changes were mild and not significant after Bonferroni correction. This could be the result of a genuine low impact, lack of statistical power and/or the capacity of this species to recolonize quickly after the impact of anthropogenic stressors. Supporting the latter argument we found a significant temporal heterogeneity of allelic frequencies in samples coming from the same sampling locality that could be attributed to the movement of adults or larvae from unaffected source populations.