Comparative cytogenetics of nine species of Hypoptopomatinae (Teleostei: Siluriformes: Loricariidae): the importance of structural rearrangements in chromosome evolution

Abstract

-Fishes of the subfamily Hypoptopomatinae are very common and found in the lowlands of cis-Andean South America from Venezuela to the north of Argentina. With the main objective of contributing for a better understanding of the importance of chromosome rearrangements in the loricariid evolution, cytogenetic analyses were conducted in nine species of Hypoptopomatinae. The results showed a marked gross karyotypic conservation with the presence of 2n=54 chromosomes in all species analyzed. The main differences were found in the karyotypic formulae level. Most species had a single interstitial Ag-NORs, however terminal Ag-NORs were observed in three species. One species exhibited two Ag-NOR-bearing chromosome pairs. The distribution of C-band positive segments was species specific but chromosome markers were observed among the species analyzed. The gross cytogenetic characteristics observed among the Hypoptopomatinae species are similar to those observed in other primitive Loricariidae species suggesting that small changes, mainly paracentric and pericentric inversion were the main events in the karyotypic evolution of this fish group.

Unrevealing the Karyotypic Evolution and Cytotaxonomy of Armored Catfishes (Loricariinae) with Emphasis in Sturisoma, Loricariichthys, Loricaria, Proloricaria, Pyxiloricaria, and Rineloricaria

“…53 From an evolutionary point of view, some authors claim that the contemporary Loricariids diversified from an ancestor with a karyotype consisting of 54 chromosomes, simple interstitial NORs, and few heterochromatin blocks. 28,54 Indeed, this pool of characteristics has been often reported in species of Trichomycteridae 55,56 and Astroblepidae, 57 two families phylogenetically close related to Loricariidae, as well as occur in most species of the basal subfamilies of Loricariidae, as in Hypoptopomatinae 54,[58][59][60] and Neoplecostominae. 39,61 However, in the Loricariinae subfamily, few species exhibit such plesiomorphic characteristics; furthermore, the representatives of this subfamily are characterized by a high numerical and structural chromosome variability, with diploid number ranging from 2n = 36 in R. latirostris to 2n = 74 in S. nigrirostrum (Table 1).…”

Ficha de Otothyris travassosi

“…Estados Bahia, Espírito Santo, Minas Gerais Biomas Mata Atlântica, Sistema Costeiro-Marinho Bacias Hidrográficas Sub-bacia Doce, Sub-bacia Jequitinhonha, Sub-bacia Litoral BA ES, Sub-bacia Litoral ES Distribuição Endêmica do Brasil: Sim Otothyris travassosi é endêmica do Brasil e ocorre nas bacias costeiras, nos estados da Bahia, Minas Gerais e Espírito Santo (Cristina et al, 2005;Pompeu, 2005;Pompeu & Martinez, 2007;Sarmento-Soares, 2007;Sarmento-Soares et al, 2007, 2008, 2009, 2013Burger et al, 2011;Roldi et al, 2014).…”