Intra- and inter-individual chromosome variation in Hoplerythrinus unitaeniatus (Pisces, Erythrinidae): a population from the Brazilian São Francisco river basin

Abstract

Chromosomal studies were carried out on a population of the fish Hoplerythrinus unitaeniatus (jeju) from Prata river in the São Francisco river basin, Minas Gerais, Brazil using conventional Giemsa staining, C-banding, silver nitrate nucleolar organizer region (Ag-NOR) staining and fluorescent in situ hybridization (FISH) with 18S and 5S rDNA probes. We found a high degree of inter-and intra-individual variability with the identification of 2n = 50, 2n = 51 and 2n = 52 karyotypes at nearly the same frequency within the population. Intra-individual variation in chromosomal morphology and, consequently, karyotype formulae was also observed, chiefly in the specimens with 2n = 50 and 2n = 52 chromosomes. Ag-NORs and 18S rDNA sites also showed numerical and chromosomal variation similar to that found for the 5S rDNA sites. Some putative hypotheses are considered in order to explain these results.

Dispersal and vicariance of Hoplias malabaricus (Bloch, 1794) (Teleostei, Erythrinidae) populations of the Brazilian continental margin

“…The H. malabaricus species group is better adapted to less oxygenated waters (Rantin et al ., ), lives in isolated populations and has seven karyotypes. Continuous, facultative air breathers of the genera Hoplerythrinus and Erythrinus (Graham, ) have five and four karyomorphs respectively, and show even larger levels of chromosome variation (Diniz & Bertollo, ; Morelli et al ., ). This familial pattern is consistent with at least three demography‐dependent chromosomal speciation models (reviewed in Rieseberg, ).…”

Differential chromosomal markers between sympatric karyomorphs of the fish Hoplias malabaricus (Bloch, 1794) (Characiformes: Erythrinidae)

“…Cuvier, 1819 , Serrasalmus spilopleura Kner, 1858 (Nakayama et al, 2000), Laetacara prope dorsigera (Heckel, 1840) (Martins-Santos et al, 2005), Hoplerythrinus unitaeniatus (Agassiz, 1829) (Giuliano-Caetano, Diniz, Bertollo, 2006), among others. Among these fi sh, the species Hoplias malabaricus represents an interesting model for the study of chromosomal rearrangements.…”

A New Report of Karyotype in the Chevron Snakehead Fish, Channa striata (Channidae, Pisces) from Northeast Thailand

“…All that we mentioned before the variations on chromosome number and morphology in Thai and Indian snakehead fish. Variations on chromosome number and morphology can be found between different populations of the same species or among different individuals of the same population and even in different cells of the same specimen (Diniz and Bertollo 2006). Furthermore, interpopulational chromosome variation has also been observed in the Erythrinid fish, Hoplerythrinus unitaeniatus (Giuliano-Caetano et al 2001, Diniz andBertollo 2003).…”