Estudos cromossômicos clássicos e moleculares no complexo de espécies Astyanax scabripinnis (Characiformes, Characidae)

• Autor(a) principal: Martinez, Juliana de Fatima
• Data de Publicação: 2020
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFSCAR
• Texto Completo: https://repositorio.ufscar.br/handle/ufscar/13227
• topic: Citogenética de peixes; Complexo de espécies; Marcadores moleculares; CIENCIAS BIOLOGICAS::GENETICA; CIENCIAS BIOLOGICAS::GENETICA::GENETICA ANIMAL

Astyanax is a fish genus of Characiformes and currently is classified as incertae sedis. Astyanax scabripinnis, one of these species, is recognized as a species complex, which is composed of 33 species. This study propose to investigate karyotypic constitution of species of this complex, throughout classical and molecular analyzes: conventional Giemsa staining, C-banding, impregnation with silver nitrate and fluorescence in situ hybridization (FISH) with different repetitive DNA probes (rDNA 5S, rDNA 18S, As51, snRNA U2, H3, H4, Rex1, Rex3, telomeric sequence and microsatellites in three species from different rivers basins: 1) Astyanax aff. scabripinnis (Alto rio Paraná); 2) Astyanax cf. intermedius (Paraíba do Sul); 3) Astyanax cf. goyanensis (Tocantins). For the latter, two units were observed occurring in sympatry, and then the presence of two karyomorphs (A and B) was considered. The analyzes showed that the species have some conserved chromosomal characteristics, such as 2n=50 chromosomes, telomeric sites and chromosomal distribution pattern of repetitive elements Rex1 and Rex3. However, the presence of variable chromosomal characters stands out among the species, showing diversity regarding chromosomal morphology, C-banding pattern, number of sites and location of AgNORs, chromosomal distribution of repetitive DNAs (rDNA 18S and 5S, As51, snRNA U2, H3, H4 and microsatellites). These results demonstrate great diversification of the karyotypic microstructure of species of Astyanax scabripinnis complex and reinforce the biodiversity of the group. In addition, the data obtained has an important role in assisting the taxonomy and evolutionary biology of the group, since they reveal the presence of different units within the complex, which can be delimited with cytogenetic assistance, showing the occurrence of exclusive chromosomal characteristics of each species