Cytotaxonomy and karyoevolution of the genus Crenicichla (Perciformes, Cichlidae)

Abstract

Karyotypes of six cichlid species of the genus Crenicichla were investigated. The species C. cincta, C. inpa, C. reticulata, C. lugubris, and C. cf. johanna were collected from Amazon basin, and C. britskii was collected from the Paraná-Paraguai basin. All of the analysed species showed 2n = 48 chromosomes; however, C. cincta, C. lugubris, C. cf. johanna, and C. britskii had a karyotype formula of 8M-SM+40ST-A, FN = 56, while C. inpa and C. reticulata exhibited the formula 6M-SM+42ST-A, FN = 54. Analysis of active Ag-NORs revealed two NOR-bearing chromosomes in all species; however, theses cistrons were located on different chromosome pairs and/or in different chromosome locations in each species. This condition bears evolutionary significance, since it is the main chromosome marker of the process of karyotypic evolution among the species of the genus Crenicichla. In general, C-banding revealed a similar constitutive heterochromatin pattern in all species, although it was possible to detect some features that led us to infer that Crenicichla also presents a species-specific heterochromatin pattern.

Chromosomal studies in Crenicichla lepidota and Australoheros facetus (Cichlidae, Perciformes) from extreme Southern Brazil

“…johana and C. britskii (Benzaquem et al 2008). The occurrence of secondary constriction and NOR was also observed in others species of this genus, like in Crenicichla sp., C. niederleinii (Loureiro et al 2000), C. iguassuensis (Mizoguchi et al 2007), C. cincta, C. inpa (Benzaquem et al 2008).…”

“…johana and C. britskii (Benzaquem et al 2008). The occurrence of secondary constriction and NOR was also observed in others species of this genus, like in Crenicichla sp., C. niederleinii (Loureiro et al 2000), C. iguassuensis (Mizoguchi et al 2007), C. cincta, C. inpa (Benzaquem et al 2008). This situation it has been usually found in Neotropical Actinopterygii (Galetti 1998), and the NORs staining by specific GC fluorochrome, like Chromomycin A 3 (CMA 3 ) and the Mitramycin, can be related with the presence of the heterochromatic blocks inside of NORs sites (Pendás et al 1993;Artoni and Bertollo 1999).…”

“…In the present work, were observed simple NORs on the first pair, evidenced for both silver nitrate impregnation and FISH with 18S rDNA probe, as observed in diverse species of Crenicichla. (Feldberg and Bertollo 1985a, b;MartinsSantos et al 1995;Loureiro et al 2000;Fenocchio et al 2003;Mizoguchi et al 2007;Benzaquem et al 2008). Thus, the occurrence of simple NORs in the first chromosome pair in C. lepidota from Polegar Lake and from São Gonçalo Stream corroborates with the hypothesis of this characteristic be a pleisiomorphy of this genus.…”

“…Others species of Crenicichla the observation of simple NOR was predominant (Feldberg and Bertollo 1985b;Loureiro et al 2000;Mizoguchi et al 2007;Roncati et al 2007;Benzaquem et al 2008), without the occurrence of multiple NORs in others species of this genus. In the present work, were observed simple NORs on the first pair, evidenced for both silver nitrate impregnation and FISH with 18S rDNA probe, as observed in diverse species of Crenicichla.…”

“…Most of cichlids from this region, analyzed until now, presents the fundamental characteristic, 2n = 48 chromosomes. However, they showed variation associated with chromosome markers, as the Nucleolar Organising Regions (NORs) (Martins-Santos et al 1995;Loureiro et al 2000;Vicari et al 2006;Mizoguchi et al 2007;Benzaquem et al 2008;Pires et al 2008Pires et al , 2010Artoni et al 2009).…”