Genetic diversity and connectivity in the Mediterranean seagrass Posidonia oceanica: state of art and future directions

Seagrasses are marine flowering plants providing key ecological services and functions in coastal zones and estuaries all across the globe. Posidonia oceanica is endemic to the Mediterranean Sea, where it forms highly productive meadows that enhance biodiversity of nearshore waters, prevent coastal erosion and contribute to climate change mitigation. Here, we aim to provide a comprehensive review on the status of the genetic knowledge of P. oceanica, with a special focus on the genetic structure of the species throughout the basin, the genetic and clonal diversities of studied populations and their potential and realized connectivity. We start providing basic information on the role of genetic and non-genetic diversity on supporting ecosystem functioning and resistance to environmental changes, in seagrasses and P. oceanica in particular. We further discuss drivers of population structure, connectivity and dispersal, and evidences of local adaptation of populations along environmental clines. An insight box is included to review the importance of sexual reproduction in P. oceanica and discuss recent massive flowering events in relation to ongoing seawater warming. We finally highlight the need and discuss the strategies to integrate current genetic knowledge with management actions to support and improve conservation of P. oceanica meadows.