Assessment of Population Connectivity in Caribbean Reef Fishes Using Microsatellite Loci

University Of Miami, Coral Gables FL

Investigators

Abstract

This research project focuses on resolving the vigorous debate over the importance of long distance dispersal versus very local dispersal of larval reef fishes. Most coral reef fish and invertebrates have a dispersive larval stage preceding a relatively sedentary juvenile and adult stage. Understanding the spatial scale at which larval dispersal operates is fundamental to understanding the connectedness of populations. Most older work suggests that wide dispersal is the dominant force, so all populations are well connected. Some recent work however, shows how oceanographic details and larval behavior may combine to favor very limited dispersal. The present research project is designed to show at what spatial scale dispersal is occurring by detecting genetic differentiation among populations. In addition to resolving this ongoing controversy, this activity will aid in the design of marine reserves by helping to identify sources and sinks of reef fish species in areas slated for protection. It may also be useful for other conservation purposes, such as the definition of separate management stocks of coral reef fish in the Caribbean and elsewhere, even in the absence of reserves Through choice of sampling sites, focal species, and genetic approach in experimental design, the likelihood of detecting population differentiation and therefore scale of dispersal has been maximized. Sampling sites have been arranged hierarchically, small sites (reefs) within larger areas (islands) within regions (groups of islands linked by large-scale currents). The three study species differ in duration of the larval stage likely to disperse: from long pelagic larval duration in bluehead wrasse to short in blue-striped grunts. Genetic analyses will involve genotyping individuals at microsatellite loci. These loci have been shown to detect subtle differentiation among fish populations where other approaches have failed. Analysis of genotype data will show at what spatial scale populations are differentiated, reef, island, or region, indicating the scale of larval dispersal. Comparison of results among species will indicate the generality of results, or their dependence of life history traits.