Genetic structure among populations of two gorgonian species inside and outside a Mediterranean Marine Protected Area

Marine Protected Areas (MPAs) are spatially delimited areas of the marine environment that are managed to conserve its biodiversity. Genetic connectivity and variability are two important parameters to take in account for proper design and manage MPAs. Gorgonians have an important ecological role contributing to provide biomass and complexity to the benthic habitats. Here, I evaluate the potential role of the MPA of Tavolara-Punta Coda Cavallo, Sardinia, in maintaining genetic diversity and connectivity among populations of two Mediterranean gorgonians: Eunicella singularis and Eunicella cavolinii. Specifically, I answered these questions: 1) Are there differences in genetic variability inside and outside the MPA? 2) What are the genetic connectivity patterns among populations inside and outside? 3) Are there differences in genetic variability and structure between the two species? 259 colonies of the two species were collected in 6 populations (2 sites outside and 4 sites inside the MPA) and genotyped using 9 microsatellite loci. The results showed that both species do not present significant genetic variability between populations sampled inside and outside the MPA. The genetic structure among populations was very low with higher FST values for E. singularis compared to E. cavolinii. E. cavolinii showed a slight significant pattern of isolation by distance. These results suggest that the genetic variability is maintained at the spatial scale of the MPA (at least for E. cavolinii) but that, in the future, will be useful to continue to monitor this variability. Finally, it is important to apply the same sample design in other MPAs to compare the pattern of connectivity and to evaluate the efficiency of the Mediterranean MPAs network. In fact, establishing a network of multiple small and interconnected reserves could increase the resilience of natural populations, including conserving genetic diversity and promoting larval connectivity.