Mitochondrial DNA and Color Pattern Variation in Three Western Atlantic Halichoeres (Labridae), with the Revalidation of Two Species
Genetic surveys of widely distributed marine species often find previously undetected biodiversity. In the present study, populations of three species of Halichoeres were sampled across their entire geographical ranges: Halichoeres cyanocephalus and Halichoeres maculipinna were sampled on both sides of the Amazon freshwater outflow, the main biogeographic barrier in the tropical western Atlantic; and Halichoeres garnoti was sampled in the Caribbean and Bermuda. Genetic divergences between populations separated by the Amazon ranged from 2.3% in H. cyanocephalus to 6.5% in H. maculipinna. There is inconsistency between color differences and genetic partitions in the species surveyed. The color differences between populations of H. cyanocephalus and H. maculipinna correspond to deep genetic partitions at the cytochrome b locus. However, genetic similarity at this same locus was observed between populations of H. garnoti with striking color differences. Based on the combination of the observed genetic differences with diagnostic color differences, the Brazilian species Halichoeres dimidiatus (Agassiz) and Halichoeres penrosei Starks, 1913 are revalidated. In addition, a neotype is designated to H. cyanocephalus (Bloch, 1791), to clarify its taxonomic status and type locality. All species analyzed have a similar larval dispersal potential, but varying degrees of genetic divergences were observed, indicating that benthic stage ecology may also play a role in speciation in this group.Abstract
Tropical western Atlantic. Numbers represent sampled locations: 1. Bermuda; 2. Bahamas; 3. Florida Keys; 4. Belize; 5. St. Croix; 6. Venezuela; 7. northeast Brazil; 8. southeast Brazil; 9. Trindade Island. Solid arrows indicate direction of mean surface oceanic currents; broken lines indicate subsurface currents
Phylogenetic tree of Halichoeres cyanocephalus (Belize) and Halichoeres dimidiatus (Brazil) unique haplotypes. Neighbor-joining bootstrap support (> 50%) indicated on nodes, maximum-parsimony support below nodes. Branch lengths are according to indicated scale; the branch leading to the outgroup (Halichoeres garnoti) was reduced by 50%
Halichoeres garnoti at the Bahamas (A) and Bermuda (B). Halichoeres dimidiatus at northeastern Brazil (C) and Halichoeres cyanocephalus at Belize (D) Halichoeres penrosei at northeastern Brazil (E) and Halichoeres maculipinna the Bahamas (F). All photos taken by Luiz Rocha, except 5C (by Gerald Allen) and 5D (by Jack Randall)
Phylogenetic tree of all (55) Halichoeres garnoti unique haplotypes. No geographical signal was detected in the phylogeny. Arrows indicate haplotypes shared between Bermuda and one or more Caribbean location; haplotypes only found in Bermuda are marked with a B. Bootstrap support (> 50%) is indicated on nodes. Branch lengths are according to indicated scale; the branch leading to the outgroup (Halichoeres poeyi) was reduced by 50%
Phylogenetic tree of Halichoeres maculipinna (Caribbean) and Halichoeres penrosei (Brazil) unique haplotypes. Neighbor-joining bootstrap support (> 50%) indicated on nodes, maximum-parsimony support below nodes. Branch lengths are according to indicated scale; the branch leading to the outgroup (Halichoeres poeyi) was reduced by 50%
Neotype of Halichoeres cyanocephalus (UF 224284). Photo by Luiz Rocha
Adult Halichoeres dimidiatus, approximately 150 mm SL, Guarapari, southeast Brazil. Photo by João Luiz Gasparini
Halichoeres penrosei, approximately 50 mm SL, Guarapari, southeast Brazil. Photo by João Luiz Gasparini
Contributor Notes
Smithsonian Tropical Research Institute, NAOS Laboratory, Unit 0948, APO AA 34002-0949, USA. rochal@naos.si.edu