WARREN, D.L.*; YOUNG, C.; IGLESIAS, T.; University of California, Davis; University of California, Davis; University of California, Davis: Reevaluating Claims of Ecological Speciation in Halichoeres bivittatus

Rocha et al. (2005) hypothesize cryptic speciation across an ecological gradient in the Slippery Dick wrasse (Halichoeres bivittatus), a widely distributed marine fish that occurs from Brazil to the southern United States. This hypothesis is based on a study of geographic variation in the mitochondrial cytochrome B gene, which exhibits a deep phylogenetic break between northern and southern lineages. Where these lineages come into contact in Bermuda and the Florida Keys spatial haplotype segregation exists on a local scale, with significant differences in haplotype frequencies between habitats separated by as little as 2 km. It was also reported that no obvious morphological differences exist between the putative species in question, although no morphological measurements have been made. I present new molecular and morphological data from specimens collected in the Florida Keys, northern Florida, the Bahamas, and Belize. Molecular data from samples taken from a broad range of habitat types in the central Florida Keys is used to assess the degree of habitat segregation, and the addition of sequences from other loci and more distant locales allows further examination of the nature of the divergence seen in cytochrome B. Measurements of jaw adductor muscle mass are also presented along with an analysis of the degree to which this morphological variable correlates with ancestry and habitat type. The hypotheses of cryptic speciation and ecological differentiation are reexamined in the light of these analyses.