Variabilidade cariotípica em populações de Hoplias malabaricus (Bloch, 1794) (Teleostei: Erythrinidae) em lagos do sudeste do Brasil

• Autor(a) principal: Jacobina, Uedson Pereira
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2199
• topic: Peixes; Citogenética; Polimorfismo cromossômico; Heterocromatina; Bitelomérica; Fishes; Cytogenetics; Chromosomal polymorphism; Heterochromatin; Bitelomerics; CNPQ::CIENCIAS BIOLOGICAS::GENETICA::GENETICA ANIMAL

The species Hoplias malabaricus popularly known as trahira occurs in almost all Brazilian basins. Seven cytogenetic forms, cytotypes are recognized within this nominal taxon. Two 2n=42 cytotypes (A and B) occur in the Doce River Basin are sympatric in the Carioca lake. This study aimed to determine the extension of sympatry of these cytotypes in other seven lakes: Tiririca, Curi, Juiz de Fora, Cristal, Lingüiça, Hortência e Marola. All populations were 2n=42 and males and females had differentiated sex chromosomes, belonging to cytotype B. Gross morphology (Giemsa staining) of cytotype B was highly stable, but high levels of variation were observed in NORs, C- banding and base-specific fluorochromes. All populations were characterized by a sex bias in bitelomeric NORs, which occurred in all males and only some females. CMA3 fluorescence of these regions was less evident. In females, an association of heterochromatin and NOR apparently defined a constant difference between the X chromosomes. Chromosomal polymorphism was more extensive and evident in heterochromatin variation, involving all chromosomes. A similarity analysis among lakes suggests an isolation by distance process of differentiation. This variation was considered as subespecific. We concluded that conditions of isolation along 14,000 years were restricted to independent processes of loss and gain of heterochromatin and that the lakes may be considered as units of management and conservation, even for a species that is resilient to the effects of introduced species.