ABSTRACT
We made a cytogenetic study of the fish Rhamdia quelen collected from the Bodoquena Plateau, an isolated national park region in Mato Grosso do Sul State, Brazil. The diploid number was 2n = 58, with 36 metacentric + 16 submetacentric + 6 subtelocentric chromosomes. We found one to three B chromosomes, which were metacentric and submetacentric and of medium size, showing both intra- and interindividual variation. The nucleolus organizer region (NOR) was located in the terminal region of the short arm of submetacentric pair 20. Staining with CMA3 fluorochrome revealed the NOR location, while there was no evidence of fluorescent staining with DAPI. C banding revealed heterochromatin mainly in the terminal regions of the chromosome arms, including the NOR pair. In addition, metacentric pair 2 showed three heterochromatic blocks in the terminal portions and in the pericentromeric region. The B chromosomes appeared euchromatic. The CB + CMA3 staining combination demonstrated only one chromosome pair with fluorescence, probably the NOR-bearing one, while CB + DAPI gave various fluorescent signals, including metacentric pair 2, indicating that these heterochromatic regions are AT-rich in this population of R. quelen. The R. quelen population in this isolated region of Brazil is chromosomally distinct from that of other populations that have been studied.
Subject(s)
Animals , Male , Female , Chromosome Banding , Cytogenetic Analysis , Nucleolus Organizer Region , Catfishes/genetics , Azure Stains , Brazil , Chromosomes/metabolism , Karyotyping , MetaphaseABSTRACT
Herein we describe spawning and egg guarding in the erythrinid fish Hoplias malabaricus observed in the southern Pantanal (19° 34' S and 57° 00' W), state of Mato Grosso do Sul, Brazil. Nests were depressions built on sandy soil in flooded areas, and contained a mean of 8,197 ± 2,204 eggs (N = 4); the mean diameter of eggs was 1.44 ± 0.09 mm (N = 400). Among 11 nests observed, eight were guarded by males and three by the pair. One male remained in the nest for six days, and two pairs remained guarding the eggs for at least three days before being captured. Females (N = 2) captured in the nest contained oocytes in their ovaries. Our observations suggest that male parental care is the normal form of parental care in H. malabaricus, but biparental care also seems to occur.
Subject(s)
Animals , Female , Male , Fishes/physiology , Maternal Behavior/physiology , Nesting Behavior/physiology , Ovum , Paternal Behavior , BrazilABSTRACT
Herein we describe spawning and egg guarding in the erythrinid fish Hoplias malabaricus observed in the southern Pantanal (19° 34' S and 57° 00' W), state of Mato Grosso do Sul, Brazil. Nests were depressions built on sandy soil in flooded areas, and contained a mean of 8,197 ± 2,204 eggs (N = 4); the mean diameter of eggs was 1.44 ± 0.09 mm (N = 400). Among 11 nests observed, eight were guarded by males and three by the pair. One male remained in the nest for six days, and two pairs remained guarding the eggs for at least three days before being captured. Females (N = 2) captured in the nest contained oocytes in their ovaries. Our observations suggest that male parental care is the normal form of parental care in H. malabaricus, but biparental care also seems to occur.
No presente estudo, descrevemos os comportamentos de desova e cuidado parental para um membro da referida família, Hoplias malabaricus, os quais foram observados no Pantanal sul (19° 34' S e 57° 00' W), Estado de Mato Grosso do Sul, Brasil. As desovas foram observadas no início da cheia, depositadas em ninhos construídos em substrato arenoso em áreas alagadas. As desovas continham, em média, 8.197 ± 2.204 ovos (N = 4); o diâmetro médio dos ovos foi de 1,44 ± 0,09 mm (N = 400). Entre 11 ninhos observados, oito foram guardados por machos e em três observamos o casal. Um macho permaneceu no ninho por seis dias, e dois casais foram observados por três dias no ninho até serem capturados. As fêmeas (N = 2) capturadas nos ninhos continham óvulos nos ovários. O cuidado parental em Hoplias malabaricus é normalmente exercido pelos machos, mas nossas observações sugerem que o cuidado biparental pode ocorrer de forma facultativa.