Estudos evolutivos no gênero Astyanax (Pisces, Characidae) / Evolutionary studies in the Astyanax genus (Pisces, Characidae).

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Astyanax is one of the species-richest genera within the order Characiformes. More than 100 representatives are widespread throughout nearly all the Neotropical region, inhabiting an array of environments, such as mountain areas, lotic and lentic river portions, lake systems and headwaters. This fish group has been a target of chromosomal studies for over 30 years, showing a remarkable cytogenetic diversity. Recently, the advances in molecular cytogenetics and DNA marker studies have provided new data about the evolutionary biology in this group, allowing revisiting former issues in species of this genus, such as their problematic taxonomical classification. In the present work, we attempted to obtain a cytogenetic characterization and analyze mtDNA segments (partial sequences of the genes ND2 and ATPase6/8) of different species and populations of Astyanax, in order to identify the evolutionary patterns and processes within the genus. Specimens from São Francisco, Tietê, Paranapanema, Mogi-Guaçu, Iguaçu, Paraíba do Sul, Ribeira de Iguape and Guapimirim hydrographic basins were collected. The results revealed phylogeographic scenarios and enabled us to establish the evolutionary relationships among the analyzed species, by associating data from two distinct classes of genetic markers. Through classic and molecular cytogenetic techniques, we present karyotypic data in A. altiparanae, A. aff. bimaculatus, A. bockmanni, A. aff. fasciatus, A. hastatus, A. mexicanus and A. ribeirae. For the phylogenetic studies, we also used, besides those sequences of the species abovementioned, data from the species Astyanax sp.B, A. giton, A. intermedius, A. lacustris, A. aff. scabripinnis, Bryconamericus iheringii, Mimagoniatis microlepis e Roeboides occidentalis. In the mtDNA analyses, sequences from the mtDNA of A. aeneus, and different haplotypes of A. mexicanus and A. bimaculatus available in the literature were included as well. Phylogeographic analyses coupled with chromosomal data were performed for the distinct populational samples in the groups A. altiparanae, A. aff. bimaculatus and A. aff. fasciatus. Both molecular and chromosomal analyses along Eastern drainage systems and nearby basins carried out in the present work provided additional information to the understanding of the evolutionary biology in the genus Astyanax. Another contribution of the present work refers to the inference on the evolutionary vi relationships in some of the most intensively studied species in the genus Astyanax, that, despite of their ecological importance and their role as a model for chromosomal and evolutionary studies, still lack more complete phylogenetic approaches. Furthermore, the association between chromosomal and molecular data revealed an interesting panorama about the evolutionary relationships in some species of this genus, as well as the evolutionary processes and patterns identified within Astyanax.

ASSUNTO(S)

astyanax karyotypic evolution astyanax evolução molecular molecular evolution. evolução cariotípica

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