Karyotypic variability in Iheringichthys labrosus (Teleostei, Pimelodidae) from the Tibagi River basin (Paraná State, Brazil)

Abstract

ABSTRACT. Cytogenetic analyses were carried out in a populational sample of Iheringichthys labrosus from the Guaraúna River (Upper Tibagi River; Paraná State, Brazil) in order to provide a karyotypic comparison with another previously studied population from the Lower Tibagi River, characterized by the presence of 32m + 8sm + 6st + 10a (2n = 56, FN = 102) and occurrence of supernumerary chromosomes (80% of individuals). The 17 specimens of I. labrosus (6 females, 10 males and 1 of unknown sex) from the Upper Tibagi River showed 2n = 56 chromosomes, a karyotype formula of 14m + 32sm + 4st + 6a (FN = 106), without evidence of sex chromosome heteromorphism or supernumerary chromosomes. The heterochromatin was detected Karyotypic variability in Iheringichthys labrosusat telomeric and centromeric positions in several chromosomal pairs. The Ag-nucleolar organizer regions were heteromorphic and located at terminal position on short arms of the 16th chromosomal pair, suggesting a positive association with heterochromatic regions. The inter-populational karyotypic differentiation reported indicates distinct evolutionary pathways within I. labrosus in the Tibagi River basin.

Can DNA barcoding accurately discriminate megadiverse Neotropical freshwater fish fauna?

“…To reinforce our hypothesis, six of these 14 species are strongly suggested in the literature as species complexes by cytogenetic markers ( Ancistrus cirrhosus [73]; Iheringichthys labrosus [74]; Synbranchus marmoratus [75]; Astyanax altiparanae [76]; Hoplias intermedius [77]; Piabina argentea [78]). Furthermore, the intra-specific lineages of 10 species are allopatric, reinforcing the fact that such lineages have independent evolutionary histories.…”

Chromosomal polymorphism in Steindachneridion melanodermatum Garavello, 2005 (Siluriformes, Pimelodidae): a reappraisal the existence of sex chromosome system in the species

“…Bar = 10 lm common characteristic, particularly in the Sorubiminae group (Fenocchio and Bertollo 1992;Swarça et al 2007). These fishes exhibit considerable variation in the karyotype, mainly related to presence of supernumerary chromosomes, crossing-over between non-homologous segments, gene duplication and transposition, which are events generally involving nucleolar organizer regions (Swarça et al 1999, Swarça et al 2001Garcia and Moreira-Filho 2008;Treco et al 2008;Ribeiro et al 2008). A number of authors have proposed that 56 chromosomes is the diploid number in Siluriformes (Oliveira and Gosztonyi 2000; Garcia and Moreira-Filho 2005), representing a basal condition of the group, and alterations in this number could be considered a derivative character.…”

Cytogenetic analyses of five amazon lizard species of the subfamilies Teiinae and Tupinambinae and review of karyotyped diversity the family Teiidae

“…Furthermore, it was possible to observe a size heteromorphism of the sites between the homologue chromosomes in the four analyzed species, a fact also described for other lizard species (O’Meally et al 2009, Srikunath et al 2009b, Srikunath et al 2011). Such a size heteromorphism is likely associated with unequal crossing-over mechanisms, rearrangements such as transpositions, deletions and/or duplications or variations in the number of rDNA copies present in such regions that would entail some changes in ribosomal sites (Gross et al 2010, Ribeiro et al 2008). …”