Environmentally-driven population structure of the bluefin tuna in the Mediterranean Sea

Atlantic Bluefin Tuna show a complex demography in the Mediterranean Sea despite it is a little basin in comparison to the long transatlantic migrations they perform. The weak population genetic structure detected through common summary statistics is difficult to infer using more sophisticated tools. An improved version of the Bayesian clustering program STRUCTURE, was used to analyse ABFT samples from the Mediterranean sea. To corroborate clustering results multivariate methods were applied to extract information from genetic markers without the use of the strong assumptions made by classical Bayesian clustering methods. Genetic and multivariate analyses detected the presence of a south to north genetic structuring through the Mediterranean Sea. Moreover correlation analyses suggested that environmental factors could have a role in shaping the identified genetic differentiation. This study confirms and defines ABFT structure in the Mediterranean Sea and highlight the influence of the environmental features on the genetic diversity of populations.