Genetic Diversity and Structure of Cymodocea Nodosa Meadows in the Aegean Sea, Eastern Mediterranean

Genetic diversity and structure were investigated among seven meadows of Cymodocea nodosa in the Aegean Sea, eastern Mediterranean basin. Analysis of three genetic loci, corresponding to the nuclear rDNA operon, revealed 12 distinct multilocus RFLP genotypes. The observed F ST pairwise values revealed, in most cases, a previously unidentified genetic diversity in Aegean populations. A relative substructuring was revealed within Pagassitikos gulf, suggesting a fragmentation possibly due to the significant factor of the previously recorded cyclonic system within the studied gulf. Moreover, individual-based landscape approach analysis supports the latter observation, suggesting the presence of three different sub-populations overall in the studied area. The observed barriers maybe related to angiosperms re-colonization from warmer parts of the eastern Mediterranean, after the last glacial maximum. AMOVA indicated the existence of hierarchical significant genetic variation between meadows within gulfs and among samples within meadows, rather than between the two gulfs, as a potential consideration for unidentified limited dispersal and demographic habits of the species in question. On the other hand, sexual reproduction events may contribute to the maintenance of genetic diversity of C. nodosa structuring in the Aegean Sea, where the species is also exhibiting extensive morphological plasticity.