The Mediterranean Sea is a two-basin system, with the boundary zone restricted to theStrait of Sicily and the narrow Strait of Messina. Two main population groups arerecognized in the Mediterranean endemic seagrass Posidonia oceanica, corresponding tothe Western and the Eastern basins. To address the nature of the East–West cleavage inP. oceanica, the main aims of this study were: (i) to define the genetic structure within thepotential contact zone (i.e. the Strait of Sicily) and clarify the extent of gene flow betweenthe two population groups, and (ii) to investigate the role of present water circulationpatterns vs. past evolutionary events on the observed genetic pattern. To achieve thesegoals, we utilized SSR markers and we simulated, with respect to current regime, thepossible present-day dispersal pattern of Posidonia floating fruits using 28-daynumerical Lagrangian trajectories. The results obtained confirm the presence of thetwo main population groups, without any indices of reproductive isolation, withthe break zone located at the level of the Southern tip of Calabria. The populations in theStrait of Sicily showed higher affinity with Western than with Eastern populations. Thispattern of genetic structure probably reflects historical avenues of recolonization fromrelict glacial areas and past vicariance events, but seems to persist as a result of the lowconnectivity among populations via marine currents, as suggested by our dispersalsimulation analysis.
|Numero di pagine||12|
|Stato di pubblicazione||Published - 2010|
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