Chromosomal studies in <Emphasis Type="Italic">Crenicichla lepidota</Emphasis> and <Emphasis Type="Italic">Australoheros facetus</Emphasis> (Cichlidae,Perciformes) from extreme Southern Brazil |
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Authors: | Giselle Perazzo Rafael Bueno Noleto Marcelo Ricardo Vicari Patricia Coelho Machado Adriana Gava Marta Margarete Cestari |
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Institution: | 1.Departamento de Genética,Universidade Federal do Paraná,Curitiba,Brazil;2.Departamento de Biologia,Faculdade Estadual de Filosofia, Ciências e Letras de Uni?o da Vitória,Centro, Uni?o da Vitória,Brazil;3.Departamento de Biologia Estrutural, Molecular e Genética,Universidade Estadual de Ponta Grossa,Uvaranas, Ponta Grossa,Brazil;4.Instituto de Biociências,Universidade Federal do Rio Grande,Rio Grande,Brazil |
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Abstract: | Fishes of the family Cichlidae generally show low karyotype variability. Nevertheless, karyotype variants have been identified within some genera, providing information about their evolutionary history. In the present study, karyotype characteristics of Crenicichla lepidota and Australoheros facetus, two sympatric species found in the São Gonçalo-Mangueira basin, were studied. Besides conventional procedures, double fluorochromes staining chromomycin A3/DAPI and fluorescent in situ hybridization (FISH) with rDNA probes were also used. Both species presented 2n = 48 chromosomes, but karyotypes were differentiated by fundamental number, which was equal to 70 in A. facetus and 56 in C. lepidota. Similar heterochromatin distribution patterns were also observed on the pericentromeric region of most chromosomes, although C. lepidota presented an additional heterochromatic block in the first pair. The Ag-NORs, 18S rDNA probe and CMA3/DAPI were coincident in location on the first and second pairs of C. lepidota and A. facetus, respectively. The minor rDNA loci (5S rDNA) were found in four sites located on two distinct chromosomal pairs in C. lepidota. Although the data obtained here to C. lepidota and to A. facetus show chromosomal characteristics considered ancestral to the family, new data are presented to both species. Additionally, this study corroborates the hypothesis in which evolutionary processes like non-Robertsonian rearrangements are involved in the diversification of the major groups of Neotropical Cichlidae. Thus, the karyotype diversification observed in A. facetus have the high fundamental number pathway while C. lepidota has others evolutionary chromosomal mechanisms. |
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