Résumé
Cladocora caespitosa (L.,1767) is the principal endemic bioconstructor coral of the Mediterranean Sea. Despite recent episodes of mortality have been documented all over the Mediterranean and a significant knowledge about the ecology, paleoecology and conservation status of this species exists, no description of its phylogeny and phylogeography is available. In order to supply this information, essential for any conservation plan, the genetic variability of some populations of C. caespitosa, collected in the northern Mediterranean Sea, has been evaluated. A 790 bp fragment of the ribosomal DNA has been amplified and cloned prior to sequencing. The genetic variability has been estimated at intraindividual, intraspecific and interspecific levels. An elevated degree of intraindividual polymorphism has been detected, but the presence of a clear phylogenetic divergence with the congener species excludes the retention of ancient phylogenetic lines, predating the origin of the species. At the intraspecific level more clades are described, yet the presence of a significant spatial genetic structure is excluded. The data also suggest a recent demographic expansion. Patterns of isolation due to biogeographic barriers within the Mediterranean Sea do not currently appear consistent for C. caespitosa, although the presence of past vicariance events is likely. This can be justified hypothesizing wide phenomena of secondary gene flow, following past divergences in few refugia areas