Meeting Abstract
In marine invertebrate species, adults are often sessile or sedentary and populations exchange individuals via dispersal of gametes and larvae. This leads to a general pattern where species that have a long larval period are expected to have more connected populations than those without larval dispersal. However, in the northwestern Mediterranean Sea, even species with relatively long-lived larvae and correspondingly high dispersal potential show a surprising number of genetic breaks over a small spatial scale. We compiled data on genetic patterns, habitat, and life history traits in ten species spanning six phyla, focusing on a 50 km area near Marseille, France. We hoped to understand what factors (e.g. life history, habitat) best explain the patterns of genetic differentiation in this region. By using data from a single area, we minimized the effects of sampling at different sites and instead focused on traits that may influence connectivity. We found that total genetic differentiation in the region varies with larval type, but not with habitat or other species traits. Additionally, genetic breaks around Marseille correspond to known patterns of circulation in the area. We also found that genetic diversity within species is weakly correlated with species diversity. Our results re-emphasize the importance of ocean circulation (i.e. physical connectivity) and larval dispersal in determining genetic connectivity in marine populations, and therefore many different ecological and evolutionary processes.
