ABSTRACT
Until recently, it was generally believed that marine species with planktonic larval dispersal should be genetically homogeneous across their geographic range. Nowadays, however, there is increasing evidence for genetically structured marine populations among larval-dispersed species, and thus a higher degree of intraspecific local variability than expected. The sometimes very complex patterns of intraspecific genetic differentiation may be due to historical environmental factors related to habitat, currents and sea level fluctuations, and/or to present-day species-specific traits and ecological factors.
