| Autor: |
Brandão KO; Leiden University Medical Center, Department of Anatomy and Embryology, S-1-P, P.O. Box 9600, 2300 RC Leiden, The Netherlands., Rocha-Reis DA; Universidade Federal de Viçosa, Campus Rio Paranaíba, Institute of Biological and Health Sciences, Laboratory of Ecological and Evolutionary Genetics, BR 354 - km 310, PO Box 22, ZIP 38810-000, Rio Paranaíba, MG, Brazil., Garcia C; Universidade Estadual do Sudoeste da Bahia, Campus Jequié, Department of Biological Sciences, Av. José Moreira Sobrinho s/n, Jequiezinho, ZIP 45206-190, Jequié, BA, Brazil., Pazza R; Universidade Federal de Viçosa, Campus Rio Paranaíba, Institute of Biological and Health Sciences, Laboratory of Ecological and Evolutionary Genetics, BR 354 - km 310, PO Box 22, ZIP 38810-000, Rio Paranaíba, MG, Brazil., de Almeida-Toledo LF; Universidade de São Paulo. Institute of Biosciences, Department of Genetics and Evolutionary Biology, Rua do Matão, 277 - Edifício André Dreyfus, Cidade Universitária, ZIP 05508090, São Paulo, SP, Brazil., Kavalco KF; Universidade Federal de Viçosa, Campus Rio Paranaíba, Institute of Biological and Health Sciences, Laboratory of Ecological and Evolutionary Genetics, BR 354 - km 310, PO Box 22, ZIP 38810-000, Rio Paranaíba, MG, Brazil. |
| Abstrakt: |
Several cytogenetic markers show chromosomal diversity in the fish such as "armoured catfish". Although studies have characterized many species in the major genera representing these Siluridae, particularly in the genus Hypostomus Lacépède, 1803, trends in chromosome evolution of this group remain unclear. The Paraíba do Sul river basin contains the armoured catfish Hypostomus affinis Steindachner, 1877, which is unique because of its distribution of repetitive DNAs, the 5S and 18S rDNA. Identified samples and registered collections in Brazilian museums were identified as the same typological species, while we observed wide variations in the physical location of this gene in the karyotype based on fluorescent in situ hybridization results. In this study, we propose that these species can represent evolutionarily independent units, as these fish frequently undergo processes such as dispersion and vicariance and that the rDNA is associated with DNA that spreads in the genome, such as transposons. Additionally, the absence of gene flow due to the distance of the sample location could intensify evolutionary processes. The phenotypes found for the 18S rDNA showed minor changes in relation to the number of sites between the lower and upper drainage regions of Paraíba do Sul. The large difference in the number of sites found for the 5S rDNA entered the same region (upper drainage of the basin) and the literature data could represent a population dynamics where an expansion of the 5S rDNA sites provides an extinct or non-sampled cytotype in this work. |
