Genetic differentiation of the temperate-subtropical stony coral Leptopsammia pruvoti in the Mediterranean Sea.

Data on genetic structure of corals living in the Mediterranean Sea are very scarce. Leptopsammia pruvoti Lacaze-Duthiers, 1897, is a gonochoric and brooding solitary coral that colonizes shaded rocky habitats. It is very abundant under overhangs, in caverns, and in small crevices, with typical densities of thousands of polyps per square meter. In the present study, a hierarchical survey of spatial models of genetic structure and potential gene flow was conducted within and among seven shallow water Mediterranean populations, which ranged from 2 to 872 km apart. Within each population, polyps were randomly collected from three patches 5 m apart. Seven allozyme loci indicated a genetic structure characterized by (1) a marked departure from Hardy-Weinberg equilibrium, with a considerable deficit of heterozygotes; (2) most genetic differentiation occurring between patches within populations (F(ST) = 0.118 to 0.206), rather than among distant populations (F(ST) = 0.052); and (3) no significant correlation between genetic differentiation and geographic distance. Localized recruitment with consequent biparental inbreeding or Wahlund effect, associated with a proportion of larvae that undergo long-distance dispersal, could explain the observed pattern of genetic structure