Diferenciação vicariante recente de Oligosarcus argenteus Günther, 1864 e Oligosarcus solitarius Menezes, 1987 nas bacias dos rios Doce e São Francisco, Minas Gerais, Brasil

• Autor(a) principal: Barros, Lucas Caetano de
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2260
• topic: Genética; Conservação; Biodiversidade; Endemismo; Genetic; Conservation; Biodiversity; Endemism; CNPQ::CIENCIAS BIOLOGICAS::ZOOLOGIA

The Rio Doce Basin is a coastal drainage isolated from the São Francisco Basin by the Serra do Espinhaço Mountains. Of this basin s 77 known native species, 37 are considered endangered with one of them, Oligosarcus solitarius Menezes 1978, being the only species endemic to the Quaternary lakes. Its sister species, Oligosarcus argenteus Günther, 1864, occurs in the same basin but is restricted to the main channel and tributaries headwaters. The present work aims to determine the specific status of Oligosarcus in the Doce River Basin and included 21 populations from the Doce River Basin and one from the upper Das Velhas River in the São Francisco Basin. This study used morphological, cytogenetic and molecular techniques. Principal Component Analysis (PCA) indicated three groups of populations: one restricted to the headwaters of the Das Velhas River, a second that occurs in the main channel of the headwaters of the Doce River, and a third occurring in the Quaternary lakes. Cytogenetic data (conventional stain, Ag-NOR and C-banding, fluorochromes, FISH, and microsatellite markings) partially corroborated the hypothesis of two groups geographically corresponding to the locals of occurrence of O. solitarius and O. argenteus in the Rio Doce Basin, but also indicated high levels of chromosomal differentiation within each group. The chromosomal variation was similar to that observed in other species of this genus. Molecular data confirmed that the speciation of the two species was recent. Considered together, the data confirmed the occurrence of differentiated but closely related populations in the Quaternary lake system and the existence of two more species in the headwaters of the Das Velhas and Doce Rivers, suggesting the need to re-evaluate the material type collected by Günther in 1861. Considering that the highest degree of chromosomal variation in O. solitarius occurred in the last 14,000 - 3,365 years, we concluded that these sister species present the highest rate of chromosomal evolution in Neotropical fish.