Abstract
Lessepsian fishes, entering the Mediterranean through the Suez Canal, have showed so far little genetic structure, but notable exceptions suggest the importance of life-history factors that may influence their patterns of spatial genetic variation. In this study, by sampling two invasive fishes with different life histories (the rabbitfish Siganus rivulatus and the filefish Stephanolepis diaspros ), we looked at evidence of population structure and selection at the boundary between the Red Sea and the Mediterranean (the Suez Canal), using thousands of molecular markers. Results illustrate two divergent patterns of genetic patterns, with little genetic structure in S. rivulatus and strong population structure in S. diaspros, even at such small spatial scale. We discuss differences in ecological characteristics between the two species to account for such differences. In addition, we report that in the face of both high ( S. rivulatus ) and low ( S. diaspros ) gene flow, loci under selection were uncovered, and some protein coding genes were identified as being involved with osmoregulation, which seems to be an important feature of individuals crossing the salinity-variable Suez Canal. The presence of genes under selection in populations near the Suez Canal supports the idea that selection may be active and essential for successful invasions right out of the gate.
POPULATION STRUCTURE AND LEVELS OF GENE FLOW IN THE MEDITERRANEAN LAND SNAIL ALBINARIA CORRUGATA
(PULMONATA: CLAUSILIIDAE)