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Pinna nobilis is the largest endemic Mediterranean marine bivalve. During past centuries, various human activities have promoted the regression of its populations. As a consequence of stringent standards of protection, demographic expansions are currently reported in many sites. The aim of this study was to provide the first large broad-scale insight into the genetic variability of P. nobilis in the area that encompasses the western Mediterranean, Ionian Sea, and Adriatic Sea marine ecoregions. To accomplish this objective twenty-five populations from this area were surveyed using two mitochondrial DNA markers (COI and 16S). Our dataset was then merged with those obtained in other studies for the Aegean and Tunisian populations (eastern Mediterranean), and statistical analyses (Bayesian model-based clustering, median-joining network, AMOVA, mismatch distribution, Tajima’s and Fu’s neutrality tests and Bayesian skyline plots) were performed. The results revealed genetic divergence among three distinguishable areas: (1) western Mediterranean and Ionian Sea; (2) Adriatic Sea; and (3) Aegean Sea and Tunisian coastal areas. From a conservational point of view, populations from the three genetically divergent groups found may be considered as different management units.

This study examined spatial relationships between rocky shore polychaete assemblages and environmental variables over broad geographical scales, using a database compiled within the Census of Marine Life NaGISA (Natural Geography In Shore Areas) research program. The database consisted of abundance measures of polychaetes classified at the genus and family levels for 74 and 93 sites, respectively, from nine geographic regions. We tested the general hypothesis that the set of environmental variables emerging as potentially important drivers of variation in polychaete assemblages depend on the spatial scale considered. Through Moran's eigenvector maps we indentified three submodels reflecting spatial relationships among sampling sites at intercontinental (>10000 km), continental (1000-5000 km) and regional (20-500 km) scales. Using redundancy analysis we found that most environmental variables contributed to explain a large and significant proportion of variation of the intercontinental submodel both for genera and families (54% and 53%, respectively). A subset of these variables, organic pollution, inorganic pollution, primary productivity and nutrient contamination was also significantly related to spatial variation at the continental scale, explaining 25% and 32% of the variance at the genus and family levels, respectively. These variables should therefore be preferably considered when forecasting large-scale spatial patterns of polychaete assemblages in relation to ongoing or predicted changes in environmental conditions. None of the variables considered in this study were significantly related to the regional submodel. Fil: Benedetti Cecchi, Lisandro. Università degli Studi di Pisa; Italia Fil: Iken, Katrin. University of Alaska; Estados Unidos Fil: Konar, Brenda. University of Alaska; Estados Unidos Fil: Cruz Motta, Juan. Universidad Simón Bolívar; Venezuela Fil: Knowlton, Ann. University of Alaska; Estados Unidos Fil: Pohle, Gerhard. Huntsman Marine Science Centre; Canadá Fil: Castelli, Alberto. Università degli Studi di Pisa; Italia Fil: Tamburello, Laura. Università degli Studi di Pisa; Italia Fil: Mead, Angela. University of Cape Town; Sudáfrica Fil: Trott, Tom. Suffolk University; Estados Unidos Fil: Miloslavich, Patricia. Universidad Simón Bolívar; Venezuela Fil: Wong, Melisa. Bedford Institute of Oceanography; Canadá Fil: Shirayama, Yoshihisa. Kyoto University; Japón Fil: Lardicci, Claudio. Università degli Studi di Pisa; Italia Fil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina Fil: Maggi, Elena. Università degli Studi di Pisa; Italia