Comparative Cytogenetics of Hoplerythrinus unitaeniatus (Agassiz, 1829) (Characiformes, Erythrinidae) Species Complex from Different Brazilian Hydrographic Basins

Abstract

Chromosomal characteristics of Hoplerythrinus unitaeniatus populations from 5 Brazilian river basins, namely Arinos (Amazonas basin), Araguaia, Paraguai, Alto Paraná, and São Francisco were analyzed by conventional Giemsa staining, C-banding, silver nitrate impregnation, and fluorescence in situ hybridization (FISH) with 18S and 5S rDNA and telomeric sequence (TTAGGG)_n probes. The diploid chromosome number was 2n = 48 in representatives of the populations from Paraguai and Alto Paraná River basins and 2n = 52 for those from the Arinos and Araguaia River basins. The São Francisco population had individuals with 2n = 50 and 52 occurring in sympatry. C-banding showed heterochromatic blocks mainly located at interstitial and pericentromeric positions in most of the chromosomes. Silver nitrate impregnation demonstrated simple NORs for representatives from Arinos and Araguaia River populations and multiple NORs for specimens from Paraguai, Alto Paraná, and São Francisco River populations. FISH with 18S and 5S rDNA probes revealed many chromosomes carrying these cistrons, with up to 21 chromosomes bearing 18S rDNA sites (Alto Rio Paraná basin) and up to 12 chromosomes with 5S rDNA sites (Paraguai basin), besides the occurrence of colocalization in all populations. FISH with telomeric sequence (TTAGGG)_n detected sites in the terminal portion of the chromosomes in all populations. These data reinforce the idea that H. unitaeniatus is a species complex. Evolutionary and biogeographical aspects of the group in the Neotropical region are discussed.

Sex Chromosome Evolution and Genomic Divergence in the Fish Hoplias malabaricus (Characiformes, Erythrinidae)

“…When compared to other members of the Erythrinidae family, similar degree of cytotaxonomic diversity can be found in Erythrinus erythrinus and Hoplerythrinus unitaeniatus groups (Bertollo, 2007 ; Cioffi et al, 2012 ; Rosa et al, 2012 ; Martinez et al, 2015 , 2016 ), while—in stark contrast—the Hoplias lacerdae species complex exhibits highly conserved karyotype structure (Blanco et al, 2011 ; de Oliveira et al, 2015 ). It is likely that the chromosomal diversity inside some Erythrinidae species might be associated with their species-specific lifestyles.…”

Evolutionary Relationships among <b><i>Boulengerella</i></b> Species (Ctenoluciidae, Characiformes): Genomic Organization of Repetitive DNAs and Highly Conserved Karyotypes

“…In this regard, the single NORs of the ctenoluciids contrast with the multiple NORs found in most erythrinids [Dergam and Bertollo, 1990;Oliveira et al, 1991;Bertollo et al, 1997;Cioffi et al, , 2011 and lebiasinids [Oliveira et al, 1991;Moraes et al, in preparation]. However, although multiple NORs are common in the erythrinids, with up to 8 sites in H. malabaricus and Erythrinus erythrinus , and 4-6 sites in Hoplerythrinus unitaeniatus , this is not a general rule in the Erythrinidae family, since species of the Hoplias lacerdae group have single NORs [Bertollo, 2007;Martinez et al, 2016;Oliveira et al, 2016].…”

High Genetic Diversity despite Conserved Karyotype Organization in the Giant Trahiras from Genus Hoplias (Characiformes, Erythrinidae)

“…Such a situation is particularly true for the Erythrinidae family, in which intra-specific chromosomal differentiation has been highlighted for several of its representatives [6,7]. A significant amount of cytogenetic data highlight the diversity displayed by populations of its three genera, including karyotypes with different diploid numbers (2n), chromosomal morphology, and sex chromosome systems, some of which are already well differentiated while others display an early stage of differentiation [6][7][8][9][10][11][12].…”