Meeting Abstract
Marine intertidal systems provide a useful, near-linear framework for examining the interactions between isolation and adaptation. Species with large geographic ranges are exposed to large environmental gradients and mechanisms that may isolate regions from one another, yet these species also tend to have broad dispersal potential. Here we expand geographic and genetic sampling of the intertidal barnacle Notochthamalus scabrosus to completely identify a cline in the distribution of two genealogical lineages, and use a coupled hydrodynamic particle tracking model to explore the likelihood that this cline is maintained by dispersal limitation alone as opposed to some form of natural selection. Our data indicate that although it is likely that the two lineages still hybridize and/or introgress, there has been considerable evolutionary divergence that is probably adaptive in nature. The relationship between these results and the overall biogeographic pattern along the Chilean coast is explored, and we suggest that oceanographic and environmental transitions near the island of Chiloé and Gulf of Ancud are likely factors in maintaining both the diversity in N. scabrosus as well as broader biogeographic transitions on the Chilean coast.
