Genetic population structure and phylogeny of the common octopus Octopus vulgaris Cuvier, 1797 in the western Mediterranean Sea through nuclear and mitochondrial markers

Genetic information is crucial for the proper exploitation of Octopus vulgaris, the most commercially valuable octopus species worldwide. The main aim of the present study was to investigate genetic structure, with the intent to inform effective management of the common octopus in Sardinia (western Mediterranean Sea), one of the most produc- tive areas within Italian waters. Patterns of population structure were assessed in 246 specimens from seven population samples. Variation in five nuclear-encoded microsatellites and sequences of two mitochondrial genes (COI and COIII) highlighted high variability and low but significant genetic differentiation among populations, which clustered into four groups corre- sponding to the north, northwest, south, and east coasts of Sardinia. Secondarily, the sequence data from Sardinia were compared with GenBank data from other areas. AMOVA and Bayesian analyses sup- ported the occurrence of significant differences within the Mediterranean Sea, and between Eastern Atlantic and Mediterranean samples. The described genetic differentiation at a regional geographical scale could be determined by a combination of historical and/or current events restricting gene flow. The occurrence of significant genetic structuring at different spatial scales is an important piece of information to define the most appropriate conservation strategies in the area, both at the local and regional level.