MCCARTNEY, Michael A.; SHULZITSKI, Kathryn; SZMANT, Alina M.; University of North Carolina, Wilmington; same; same: Multilocus Microsatellite Analysis of Species Boundaries Within the Montastrea annularis Coral Species Complex

Molecular studies of the Montastrea annularis species complex, which contains the most ecologically dominant reef building corals in the western Atlantic, have failed to yield a consensus on the status of speciation within the complex. Individual-based analyses of genotypes at multiple DNA microsatellite loci have served as sensitive indicators of reproductive isolation, and of introgression, between members of other groups of incipient species. Our study extends such an analysis to Montastrea, using genotypes at 5 microsatellite loci in over 100 colonies haphazardly collected with respect to morphological species designation off La Parguera, Puerto Rico. Bayesian analysis using STRUCTURE and assignment methods produced three clusters of genotypes in our sample. Montastrea faveolata colonies were placed exclusively within one of these clusters, hence confirming the distinctiveness of this morphospecies previously obtained at other loci. Curiously, however, the two remaining clusters each contain roughly equal numbers of M. annularis and M. franksi, a result that is qualitatively similar to that from previous DNA sequence analysis of a single nuclear (AFLP) locus on this population. We also discuss the results from microsatellite-based “hybrid index” calculations on a subset of colonies that showed evidence of introgression at the AFLP locus.