Southeastern Fishes Council, Chattanooga, TN, Nov 2011.

Using GIS to predict how changes in sea level potentially influence phylogeographic patterns in freshwater and coastal marine fishes.

P.J. Unmack.

Most research within phylogeography has concentrated on first identifying a biogeographic pattern from their phylogenetic results and then explaining this pattern due to some earth history event. My goal is to shift the focus in the opposite direction. That is, to map relevant aspects of earth history across the landscape and then see how consistent these earth history patterns are relative to the phylogenetic data. If these aspects of earth history are important in determining biogeographic patterns then phylogeographic patterns should be fairly consistent with them. If the patterns are not consistent then it suggests that we need to find alternative explanations for the observed phylogeographic patterns and that the earth history factors are not strong forces with broad impact. Here I present two examples using different aspects of continental shelf width to predict phylogeographic patterns. The first quantifies the relative degree and difficulty of movement of obligate freshwater organisms between drainage basins via low sea level connections. The second aspect of this research is to quantify potential habitat for coastal marine fishes at different sea level heights to contrast potential changes in population size since the last low sea level stand. Using GIS I have developed datasets that allow researchers to visualize and quantify continental shelf width for any region of the world. I provide some examples that demonstrate the utility of this approach.