Cytogenetic studies in six species of Scinax (Anura, Hylidae) clade Scinax ruber from northern and northeastern Brazil

Abstract

Scinax species are still underrepresented in cytogenetic studies, mainly with respect to populations from northeastern and northern Brazil. In this study, we provide new chromosomal information on Scinax boesemani, S. camposseabrai, S. garbei, S. pachycrus, S. trilineatus and S. x-signatus, all belonging to clade S. ruber. They were collected at two locations in the Caatinga biome (northeastern Brazil) and at one in the Amazon (northern Brazil) biomes. Chromosomes were analyzed by conventional staining, C-banding, Ag-NOR staining, and fluorochrome staining. All species shared a modal diploid value of 2n = 24 and fundamental arm number (FN) of 48. Moreover, both chromosomal size and morphology were similar to other species in this Scinaxclade. C-banding revealed centromeric heterochromatin in all species, along with terminal species-specific C-bands in some species. Active nucleolar organizer regions (Ag-NORs) were identified at 11q in most species, except for S. boesemani and S. garbei (Ag-NORs at interstitial region of 8q). Differing from most anurans, GC-rich regions were not restricted to NORs, but also coincident with some centromeric and terminal C-bands. These data contribute to the cytotaxonomy of Scinax by providing chromosomal markers and demonstrating the occurrence of microstructural rearrangements and inversions on chromosomal evolution of Scinax.

Comparative analysis based on replication banding reveals the mechanism responsible for the difference in the karyotype constitution of treefrogs Ololygon and Scinax (Arboranae, Hylidae, Scinaxinae)

“…Nevertheless, the data obtained herein for species of Ololygon and Scinax and those of Nogueira et al (2015a), Nogueira et al (2015b), and Peixoto et al (2015) for the species of the former Scinax catharinae and Scinax ruber clades are inconsistent for a clear-cut differentiation of the two karyotypic constitutions with this chromosome marker.…”

“…Nevertheless, a possible third karyotypic constitution that had been suggested by that author was not confirmed here or by Cardozo et al (2011) who studied a large sample of species of Scinax (lato sensu). Subsequent studies (Oliveira 2011, Nogueira et al 2015a, Nogueira et al 2015b, Peixoto et al 2015, Lourenço et al 2016, and Peixoto et al 2016 confirmed that the two chromosome constitutions remained invariably the same, indicating that the karyotypes are relatively conserved within each of the two taxonomic groups.…”

“…Additionally, the combined analysis with phylogeny allowed these authors to establish that the characteristic Ag-NORs marker in small pair 11, as exhibited by the species in the S. ruber clade, was considered a plesiomorphy, whereas the location in pair 6 in the species of the S. catharinae clade is a derivative condition. Only recently, a small number of species of Scinax (lato sensu) have had their karyotypic analyses extended through the use of more advanced cytogenetic techniques, such as investigation of the nature of repetitive regions using fluorochrome staining or fluorescent in situ hybridization (FISH) with microsatellite probes, and the location of ribosomal or telomeric sequences using the FISH technique (Oliveira 2011, Nogueira et al 2015a, Nogueira et al 2015b, Peixoto et al 2015, Peixoto et al 2016.…”

Comparative analysis based on replication banding reveals the mechanism responsible for the difference in the karyotype constitution of treefrogs Ololygon and Scinax (Arboranae, Hylidae, Scinaxinae)

“…Additionally, the combined analysis with phylogeny allowed these authors to establish that the characteristic Ag-NORs marker in small pair 11, as exhibited by the species in the S. ruber clade, was considered a plesiomorphy, whereas the location in pair 6 in the species of the S. catharinae clade is a derivative condition. Only recently, a small number of species of Scinax ( lato sensu ) have had their karyotypic analyses extended through the use of more advanced cytogenetic techniques, such as investigation of the nature of repetitive regions using fluorochrome staining or fluorescent in situ hybridization (FISH) with microsatellite probes, and the location of ribosomal or telomeric sequences using the FISH technique (Oliveira 2011, Nogueira et al 2015a, Nogueira et al 2015b, Peixoto et al 2015, Peixoto et al 2016). …”

Karyological study of Ololygon tripui (Lourenço, Nascimento and Pires, 2009), (Anura, Hylidae) with comments on chromosomal traits among populations

“…In Hylidae, high level of karyotypical diversity has been reported in genera Aplastodiscus Lutz, 1950, Hypsiboas Wagler, 1830, and Phyllomedusa Wagler, 1830 (Carvalho et al 2009, Ferro et al 2012, Gruber et al 2012, Gruber et al 2013). On the other hand, karyotypes of Ololygon and Scinax Wagler, 1830 are highly conserved: all species show 2n = 24, and FN = 48, and morphological differences are restricted to slight variations between corresponding homeologous chromosomes (Nunes and Fagundes 2008, Cardozo et al 2011, Nogueira et al 2015, Peixoto et al 2015). Within Ololygon , only 19 recognized species and four unnamed taxa have been karyologically studied.…”