Filogeografia citogenética e molecular em populações de traíras Hoplias malabaricus (Bloch, 1794), do leste do Brasil

• Autor(a) principal: Santos, Udson
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4717
• topic: Peixes dulcícolas; Hibridização in situ; Relógio molecular; mtDNA; América do Sul; Freshwater fish; In situ hybridization; Molecular clock; mtDNA; South America; CNPQ::CIENCIAS BIOLOGICAS::GENETICA::GENETICA ANIMAL

The Neotropical freshwater fish fauna is considered the richest of the world. This diversity is the direct result of the complex palaeohydrological history of the Central and South-American rivers, a process that promoted vicariance and dispersion of the aquatic biota along millions of years. The common trahira H. malabaricus is a widespread, sedentary predatory Neotropical characin. Due to its abundance and tolerance to transportation and laboratory conditions, the trahira has become a relevant model organism for experimental biology. H. malabaricus populations are characterized by 7 karyomorphs named A-G. The allopatric and sympatric distribution of these karyomorphs has been considered as evidence for the existence of multiple lineages that behave as good species within this nominal taxon. To test this hypothesis, biogeographic, cytogenetic and molecular (mitochondrial DNA) patterns were analyzed in 17 populations (73 specimens) from 12 basins in northeasten and southeastern Brazil. Cytogenetic patterns indicated a XX/XY chromosome system in karyomorph 2n=40F. Molecular data indicated absence of gene flow among karyomorphs 2n=40 and 2n=42 and provided the first evidence of a coastal origin of the 2n=42 karyomorphs in the Jacaré River. The absence of a constant molecular rate of substitution hampered a correlation of past dispersal events and it was interepreted as an effect of extreme demographic fluctuations in this species complex. These results indicate that karyotypic identification is relevant and necessary for placing all experimental data in a phylogenetic context.