B chromosomes in four different populations of Rhamdia quelen (Siluriformes, Heptapteridae): a comparative study of frequency and distribution.
In the present study 25 specimens of Rhamdia quelen from four different localities were analyzed cytogenetically. All showed a diploid number of 58 chromosomes, with a karyotypic formula of 36m + 16sm + 6st and FN = 116. Metacentric B chromosomes showing inter- and intraindividual variation were observed in all populations. C-banding revealed differences in the heterochromatin distribution pattern, with evidence of completely heterochromatic B chromosomes in three populations: Agua das Pedras, Agua dos Patos and Taquari rivers, and partially heterochromatic B chromosomes in the population at the fish farm station in Timbó/SC. The occurrence of B chromosomes in such distinct populations suggests that they could have arisen from the same ancestral state, before the geographic dispersal of this species.
Universidade Estadual de Londrina, Centro de Ciencias Biológicas, Departamento de Biologia Geral 86051-970, Londrina, Paraná, Brasil.
Vivian Patrícia Oliveira
VP
de Moraes
Juliana de Souza
Jde S
Carneiro
Ana Lúcia
AL
Dias
D000818:Animals; D001938:Brazil; D002397:Catfishes / Q000235:genetics*; D002875:Chromosomes / Q000235:genetics*; D005260:Female; D007621:Karyotyping; D008297:Male