Postdoctoral Fellow

Exploring environmental correlates of range limits across a marine biodiversity hotspot

PI(s): Elizabeth J Sbrocco
Start Date: 1-Jan-2012
End Date: 31-Dec-2013
Keywords: biodiversity, biogeography, ecological niche modeling, dispersal, ecology

Steep latitudinal and longitudinal gradients in species richness coupled with high levels of species endemism make the Coral Triangle the global epicenter of marine biodiversity. Although the mechanisms behind the origins and maintenance of this pattern are poorly resolved, insight can be gained by looking for common phylogeographic patterns within co-distributed species – concordance in the spatial locations of genetic breaks suggests common physical processes are at work in limiting dispersal. When phylogeographic barriers match boundaries between sister species or regions of high endemism, the suggested mechanism can be inferred to be temporally stable on an evolutionary timescale.

Marine phylogeographic breaks are often attributed to ocean currents that act to reinforce patterns formed during historical isolation through Pleistocene glacial periods. I argue that environmental barriers could also serve to reinforce these patterns and I propose two mechanisms that can be tested: 1) adaptive divergence to environmentally distinct refugial habitats limit the ability of divergent lineages to expand their ranges, or 2) divergent lineages are found in environmentally similar habitats but are bound to refugial ranges by zones of unsuitable habitat. I will test these hypotheses using an integrative synthetic approach, combining phylogeographic datasets, GIS methods, ecological niche modeling, and Bayesian statistics. Until very recently, such approaches were impossible due to data and methodological limitations, thus this work will pave the way for future studies investigating environmental limits to the ranges of marine species. It also fills a major gap in our understanding of diversification within the world's hottest marine biodiversity hotspot.