Interpopulational comparative cytogenetics analysis among three Astyanax (Characiformes: Incertae Sedis) species of two streams of upper Paraná River basin, Brazil

Abstract

Populations of Astyanax paranae, Astyanax fasciatus and Astyanax altiparanae collected from the Pindorama and Lopei streams (upper Paraná river basin, Brazil) were cytogenetically studied, checking for chromosomal differentiation and the evolutionary trend in the three species. Forty-eight chromosomes (8m + 20sm + 10st + 10a) were observed in both populations of Astyanax paranae. Astyanax fasciatus exhibited 50 chromosomes (8m + 18sm + 10st + 14a, Pindorama stream; 8m + 14sm + 12st + 16a, Lopei stream). The diploid number for A. altiparanae was 50 chromosomes in both populations (6m + 30sm + 4st + 10a). The three studied species exhibited multiple AgNORs with differences among the populations of A. paranae and A. fasciatus. Regarding the heterochromatin distribution, interpopulational differences were observed in the three species. The data of the present study demonstrate that both A. paranae and A. fasciatus exhibit karyotypical interpopulational differences more conspicuous than A. altiparanae populations, probably due to the characteristics that restricted both the A. paranae and the A. fasciatus to the upper portion of the streams, leading to the fixation of different chromosomal rearrangements in the populations. However, the absence of conspicuos interpopulational karyotypical differences in A. altiparanae suggests a gene flow between both populations. In the present study, the role of the streams as an environment which maintains the diversity of fish with different genetic pools became evident.

Chromosomal Microstructure Diversity in Three Astyanax (Characiformes, Characidae) Species: Comparative Analysis of the Chromosomal Locations of the 18S and 5S rDNAs

“…24,26 According to Ferro et al, 24 multiple Ag-NORs occur in A. scabripinnis, and this condition may be typical of Astyanax species (see e.g., Refs. [27][28][29].…”

New Protocol for Cell Culture to Obtain Mitotic Chromosomes in Fishes

“…Considering the possible advantages of cell culture, the aim of this study was to develop a quick and easy methodology for fish cell culture, with a direct application, to obtain mitotic chromosomes for cytogenetic studies. The species Astyanax altiparanae (Characiformes) was used as a model, since this species has been the subject of different types of cytogenetic studies [18,19,20,21,22].…”

Cytogenetic markers as tools in delimiting species of the highly diverse Neotropical fish Bryconamericus (Characiformes: Characidae)

“…ecai differed from other populations already studied (Santos et al, 2012(Santos et al, , 2017. This indicates a high degree of chromosomal rearrangements, common in other Stevardiinae genera such as Piabina (Fernandes et al, 2010;Pazian et al, 2012;Piscor et al, 2018) and Piabarchus (Fernandes et al, 2010, cited as Bryconamericus), and in other complex groups of Characidae, such as the Serrasalmus (Martins-Santos et al, 1994;Centofante et al, 2002), Cheirodon (Soto et al, 2018) and Astyanax (Yano et al, 2014;Paiz et al, 2015;Nishiyama et al, 2016, among others).…”