Biogeografia histórica do lambari de ampla distribuição Astyanax aff. bimaculatus (Teleostei: Characidae) no sudeste brasileiro, com base em padrões de variação citogenéticos e moleculares

• Autor(a) principal: Cunha, Marina Souza da
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4810
• topic: Genética animal; Lambari (Peixe) - Citogenética; Lambari (Peixe) - Citogenética; Lambari (Peixe) - Morfologia; Astyanax bimaculatus; Astyanax lacustris; Brasil - Sudeste; Animal genetics; Tetra (Fish) - Cytogenetics; Tetra (Fish) - Cytogenetics; Tetra (Fish) - Morphology; Astyanax bimaculatus; Astyanax lacustris; Brazil - South east; CNPQ::CIENCIAS BIOLOGICAS::GENETICA::GENETICA ANIMAL

The species of the genus Astyanax are widely distributed in the Neotropical region and have few morphological, ecological and behavioral differences, which complicates the taxonomic classification of this taxon. The nominal species Astyanax bimaculatus was described by Linnaeus in 1758 and currently species with two oval spots that occur in several Neotropical basins are considered as belonging to bimaculatus complex. The objective of this study was to determine the cytogenetic and molecular characteristics (mitochondrial DNA) of 19 populations currently assigned to Astyanax bimaculatus from complex coastal basins of southeastern Minas Gerais using conventional staining, nucleolar organizer regions Ag-NORs, C-band, DAPI, FISH and the gene cytochrome oxidase I - COI. Data were compared with other species of the complex. The karyotype 6m +20 sm +18 st +6 t occurred in all populations, with Ag-NORs ranging from two to eight stained chromosomes. The C-banding showed centromeric and pericentromeric markings, evidenced by the fluorochrome DAPI. Fluorescent 18S and 5S rDNA probes marked one chromosome pair respectively. The phylogeny obtained with the COI gene indicated the presence of two haplogroups with large molecular distance between them: haplogroup I was more closely related to the populations of the São Francisco River Basin, while haplogroup II was subdivided into a group which was more related to populations from the upper Paraná (IIA) and another group formed exclusively by coastal haplotypes (IIB). The karyotype uniformity of coastal populations is greater than the recognized Astyanax altiparanae, suggesting the persistence of large populations. Polymorphisms involving C-band patterns indicate that the addition and reduction of heterochromatin blocks are compatible with intraspecific variation. The molecular data suggest that coastal basins received migrants from continental basins, with more recent geodispersion of a coastal haplogroup, probably related to the dynamic confluence of coastal basins during glacial periods. The genetic similarity between São Francisco River Basin and coastal basins indicates that the nominal species Astyanax lacustris does not represent a valid taxon. While the Upper Paraná Basin maintained a molecular identity consistent with the existence of the nominal taxon Astyanax altiparanae that, agreeing with the cytogenetic data, also occurs in the Paraíba do Sul River Basin. It is concluded that the bimaculatus complex in southeastern Brazil is composed by three lineages, including only two species Astyanax aff. bimaculatus present in São Francisco and coastal basins and A. altiparanae present in the Upper Paraná.