Corrigendum: Evolutionary tracks of chromosomal diversification in surgeonfishes (Acanthuridae: Acanthurus) along the world's biogeographic domains.

[This corrects the article DOI: 10.3389/fgene.2021.760244.].

Evolutionary Tracks of Chromosomal Diversification in Surgeonfishes (Acanthuridae: Acanthurus) Along the World's Biogeographic Domains.

Fishes of the genus Acanthurus (Acanthuridae) are strongly related to reef environments, in a broad biogeographic context worldwide. Although their biological aspects are well known, cytogenetic information related to this genus remains incipient. In this study, Acanthurus species from populations inhabiting coastal regions of the Southwest Atlantic (SWA), South Atlantic oceanic islands (Fernando de Noronha Archipelago and Trindade Island), Greater Caribbean (GC), and Indo-Pacific Ocean (the center of the origin of the group) were analyzed to investigate their evolutionary differentiation. For this purpose, we employed conventional cytogenetic procedures and fluorescence in situ hybridization of 18S rDNA, 5S rDNA, and H3 and H2B-H2A histone sequences. The Atlantic species (A. coeruleus, A. chirurgus, and A. bahianus) did not show variations among them, despite their vast continental and insular distribution. In contrast, A. coeruleus from SWA and GC diverged from each other in the number of 18S rDNA sites, a condition likely associated with the barrier created by the outflows of the Amazonas/Orinoco rivers. The geminate species A. tractus had a cytogenetic profile similar to that of A. bahianus. However, the chromosomal macrostructures and the distribution of rDNA and hisDNA sequences revealed moderate to higher rates of diversification when Acanthurus species from recently colonized areas (Atlantic Ocean) were compared to A. triostegus, a representative species from the Indian Ocean. Our cytogenetic data covered all Acanthurus species from the Western Atlantic, tracked phylogenetic diversification throughout the dispersive process of the genus, and highlighted the probable diversifying role of ocean barriers in this process.

Co-located 18S/5S rDNA arrays: an ancient and unusual chromosomal trait in Julidini species (Labridae, Perciformes).

Wrasses (Labridae) are extremely diversified marine fishes, whose species exhibit complex interactions with the reef environment. They are widely distributed in the Indian, Pacific and Atlantic oceans. Their species have displayed a number of karyotypic divergent processes, including chromosomal regions with complex structural organization. Current cytogenetic information for this family is phylogenetically and geographically limited and mainly based on conventional cytogenetic techniques. Here, the distribution patterns of heterochromatin, GC-specific chromosome regions and Ag-NORs, and the organization of 18S and 5S rDNA sites of the Atlantic species Thalassoma noronhanum (Boulenger, 1890), Halichoeres poeyi (Steindachner, 1867), Halichoeres radiatus (Linnaeus, 1758), Halichoeres brasiliensis (Bloch, 1791) and Halichoeres penrosei Starks, 1913, belonging to the tribe Julidini were analyzed. All the species exhibited 2n=48 chromosomes with variation in the number of chromosome arms among genera. Thalassoma noronhanum has 2m+46a, while species of the genus Halichoeres Rüppell, 1835 share karyotypes with 48 acrocentric chromosomes. The Halichoeres species exhibit differences in the heterochromatin distribution patterns and in the number and distribution of 18S and 5S rDNA sites. The occurrence of 18S/5S rDNA syntenic arrangements in all the species indicates a functionally stable and adaptive genomic organization. The phylogenetic sharing of this rDNA organization highlights a marked and unusual chromosomal singularity inside the family Labridae.

Genetic multipartitions based on D-Loop sequences and chromosomal patterns in brown chromis, Chromis multilineata (Pomacentridae), in the Western Atlantic.

Connectivity levels among Brazilian reef fish fauna populations have attracted growing interest, mainly between mainland shores and oceanic islands. The Pomacentridae, whose phylogeographic patterns are largely unknown in the Atlantic, are a family of dominant fish in reef regions. We present data on the variability and population structure of damselfish Chromis multilineata in different areas along the northeast coast of Brazil and in the waters around the oceanic islands of Fernando de Noronha (FNA) and Saint Peter and Saint Paul Archipelago (SPSPA) through analysis of the HVR1 mtDNA sequence of the control region. The remote SPSPA exhibits the highest level of genetic divergence among populations. Conventional and molecular cytogenetic analysis showed similar karyotype patterns (2n=48 acrocentrics) between these insular areas. Our estimates reveal three genetically different population groups of C. multilineata on the Brazilian coast. The level of genetic structure is higher than previous data suggested, indicating complex panel of interactions between the oceanic island and coastal populations of Brazil.