Local and regional genetic connectivity in a Caribbean coral reef W sh

Coupled bio-physical models of larval dispersal predict that the Costa Rica–Panama (CR–PAN) reefs should constitute a demographically isolated region in the western Caribbean. We tested the hypothesis that CR–PAN coral reef Wsh populations would be isolated from Mesoamerican Barrier Reef System (MBRS) populations. To test that, we assessed population genetic structure in bicolor damselWsh (Stegastes partitus) from both regions. Adult Wsh were genotyped from Wve reefs in CR–PAN and from four reefs along the MBRS at 12 microsatellite loci. Between-region FST (FST = 0.0030, P < 0.005) and exact test (x = 74.34, df = 18, P < 0.0001) results indicated that there is weak but signiWcant genetic diVerentiation between regions, suggesting some restriction in connectivity along the Central American coastline, as predicted by bio-oceanographic models. Additionally, there is among-site genetic structure in the CR–PAN region, relative to the MBRS and between regions, suggesting higher self-recruitment within CR–PAN. This Wnding may be explained by diVerences in habitat characteristics. Introduction Most coral reef Wshes have a pelagic larval stage with potential to disperse long distances (Leis 1991). Because adult reef Wshes are relatively sedentary (Sale 1980), the pelagic stage is an important link for population connectivity between patchily distributed habitat. Connectivity plays key roles in local adaptation and speciation, population replenishment and the likelihood of local extinction. Connectivity is also important for coral reef management; for example, it provides a mechanism for no-take reserves to enhance Wsh production outside their borders (Botsford et al. 2001; Hilborn et al. 2004; Kritzer and Sale 2004). Caribbean reef ecosystems are experiencing serious decline (Gardner et al. 2003) and need urgent management action. The Mesoamerican Barrier Reef System (MBRS) and the reefs fringing the eastern coast of Central America constitute critically important regions of biodiversity concentration. A quantitative understanding of patterns of connectivity in that region is of particular relevance for management and conservation. Based on coupled bio-physical modeling of oceanographic data, habitat availability and larval behavior of coral reef Wsh in the Caribbean, four distinct regions of population isolation have been identiWed: the eastern Caribbean, the western Caribbean, the Bahamas–Turks and Caicos Islands, and the region at the periphery of the Panama–Colombia gyre (Cowen et al. 2006). Based on this, the Panama–Colombia reefs were predicted to be isolated from the remainder of the Caribbean, due to limited larval exchange (Cowen et al. 2006). Additionally, this region is predicted to have higher self-recruitment than the others, due to low importation from upstream locations (Cowen et al. 2006). Genetic work on corals has validated some of these regional connectivity predictions, for example the Communicated by T. Reusch. E. Salas (&) · H. Molina-Ureña Centro de Investigación en Ciencias del Mar y Limnología (CIMAR), Universidad de Costa Rica San Pedro de M.O. , 11501-2060 San Jose, Costa Rica e-mail: salas.e@gmail.com R. P. Walter · D. D. Heath Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON N9B 3P4, Canada