Genetic studies of white grunt, Haemulon plumieri, indicate restricted gene flow and deep phylogeographic divergence between Caribbean, Trinidadian and Atlantic Coast populations

R. W. Chapman and G. R. Sedberry
South Carolina Department of Natural Resources, Marine Resources Research Institute, 217 Fort Johnson Road, Charleston South Carolina, 29412; Ph. 843-762-5402, Fax 843-762-5110, chapmanr@mrd.dnr.state.sc.us

White grunt, Haemulon plumieri were taken from North Carolina, South Carolina, Florida, the Yucatan peninsula, Belize, Puerto Rico, and Trinidad. Genetic variation was assessed in the ND-1 region of the mtDNA molecule and at microsatellite loci. Analysis of mtDNA variation found three highly distinctive lineages. A northern type was found from the Carolina's and Gulf of Mexico south to the Florida Key's. A southern form was found in the Florida Keys, Yucatan, Belize and Puerto Rico. A third haplotype was found exclusively in Trinidad. Analysis of DNA sequences indicate that the Caribbean and Carolinian forms are more closely related (2% divergence) to each other than either is to the Trinidad (7% divergence). These data are subject to at least two interpretations. First, the may indicate zoogeographic structuring in white grunt. If true, this indicates that genetic exchange is far more restricted than one might expect in a pelagically dispersed organism. Second, the magnitude of genetic differences were compatible with that found between closely related species and may that white grunt, as currently, recognized is actually three distinct species. Analysis of nuclear gene variation strongly supported the first hypothesis.