Chromosomal rearrangements associated with pelagic larval duration in Labridae (Perciformes) Delanne Cristina Souza de Sena ⁎ , Wagner Franco Molina 1 Departamento de Biologia Celular e Genética, Universidade Federal do Rio Grande do Norte, 59078-970, Natal, RN, Brazil Received 15 June 2006; received in revised form 28 August 2007; accepted 29 August 2007 Abstract The family Labridae is one of the largest and most important groups of reef fishes in the Southern Atlantic. There is a remarkable ecologic interest in this family because of their complex interactions in the reef environment. Predictions of genetic variability in fish based on biological patterns have often been contradictory. The present work aimed to increase the cytogenetic data about the family and verify the possible correlation between larval pelagic phase and chromosomal rearrangements based on the putative basal Perciformes karyotype (2n = 48a). Therefore, cytogenetic analyses were performed in the species Halichoeres brasiliensis (2n = 48, 48a, FN = 48); Halichoeres radiatus (2n = 48, 48a, FN = 48) and in three populations of Halichoeres poeyi (2n = 48, 4m + 44st-a, FN = 52) from Brazilian coastline. A conserved diploid number was observed in all species and populations. Single NORs were identified in H. brasiliensis and in two populations of H. poeyi (BA and RJ), while multiple NORs were observed in H. radiatus and in H. poeyi from Rio Grande do Norte. The constitutive heterochromatin is reduced and distributed over centromeric and pericentromeric regions. The ribosomal sites allowed differentiating two groups of H. poeyi along the Brazilian coast; one of them comprising the population from RN, bearing multiple NORs, and another representing the populations from BA and RJ, bearing single NORs. The recently separated species, H. brasiliensis and H. radiatus, although presenting similar diploid numbers and chromosomal formulae, could be distinguished by the number of NOR-bearing chromosomes. The results revealed an evolutionary pattern chiefly derived from pericentric inversions. The correlation between larval pelagic phase and cytogenetic data on Labridae indicates that the degree of karyotypic diversification reported within this family, ranging from a highly conserved to a derived pattern, is probably influenced by the species-specific duration of larval pelagic phase. © 2007 Elsevier B.V. All rights reserved. Keywords: Fish cytogenetics; Halichoeres; Labridae; Pelagic period 1. Introduction The family Labridae represents the third largest group of Perciformes, comprising 4 subfamilies — Bodiani- nae, Corinae, Cheilininae and Pseudodacinae, 60 genera and about 500 species. Labrids are popularly known as wrasses and are widespread throughout the Brazilian coast. These marine fishes are found in reef sites and most species are asynchronic hermaphrodites (Kuwa- mura and Nakashima, 1998). The genus Halichoeres is widely distributed over the Atlantic Ocean and taxono- mical identification of some species are somewhat difficult. This genus is very specious, comprising about 20% of Labridae species ( Nelson, 1994). Journal of Experimental Marine Biology and Ecology 353 (2007) 203 – 210 www.elsevier.com/locate/jembe ⁎ Corresponding author. R. Almira Melo do Amaral, 1963, Lagoa Nova, 59076-750, Natal, RN, Brazil. Tel.: +55 84 3206 2465. E-mail address: del_sena@yahoo.com (D.C.S. de Sena). 1 Tel.: +55 84 3211 9209 (r-214); fax: +55 84 3215 3346. 0022-0981/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jembe.2007.08.020