Abstract:The genetic variability of the "curimba", Prochilodus lineatus, from three locations in the Paraná river basin, was investigated by starch gel electrophoresis. A total of 160 specimens were analyzed for 19 enzymes, 12 of which permitted successful interpretation of electrophoretic patterns. Eighteen loci were identified and six of them proved to be polymorphic (EST-1*, EST-2*, IDH-1*, PGM-1*, PGM-2*, LDH-2*). Mean heterozygosity was considered high (13%) by comparison with the literature. A low level of differ… Show more
“…Previous enzyme electrophoresis, used to quantify the genetic variations of P. lineatus collected from three sites in the Paraná river basin, detected no genetic divergences among the three samplings, suggesting a unique genetic pool of P. lineatus spread along the studied area (Revaldaves et al, 1997).…”
Many factors have contributed to the destruction of fish habitats. Hydroelectric dams, water pollution and other environmental changes have resulted in the eradication of natural stocks. The aim of this study was to detect the genetic variation in Prochilodus marggravii from three collection sites in the area of influence of the Três Marias dam (MG) on the São Francisco river (Brazil), using the RAPD technique. The results obtained revealed that the fish in the downstream region nearest the dam have a higher similarity coefficient than those from the other sampling sites that may be related to differences in environmental characteristics in these regions. Additionaly, significant differences in the band frequencies were observed from one collection site to another. These both findings suggest the occurrence of a structured population and have important implications for the conservation of the genetic variability of distinct natural P. marggravii stocks.
“…Previous enzyme electrophoresis, used to quantify the genetic variations of P. lineatus collected from three sites in the Paraná river basin, detected no genetic divergences among the three samplings, suggesting a unique genetic pool of P. lineatus spread along the studied area (Revaldaves et al, 1997).…”
Many factors have contributed to the destruction of fish habitats. Hydroelectric dams, water pollution and other environmental changes have resulted in the eradication of natural stocks. The aim of this study was to detect the genetic variation in Prochilodus marggravii from three collection sites in the area of influence of the Três Marias dam (MG) on the São Francisco river (Brazil), using the RAPD technique. The results obtained revealed that the fish in the downstream region nearest the dam have a higher similarity coefficient than those from the other sampling sites that may be related to differences in environmental characteristics in these regions. Additionaly, significant differences in the band frequencies were observed from one collection site to another. These both findings suggest the occurrence of a structured population and have important implications for the conservation of the genetic variability of distinct natural P. marggravii stocks.
“…Nevo (1978) estimated from data in the literature a mean P value of 15.2%, for 51 species of Teleostei. Studies carried out in fish species from Brazilian rivers show P values with a wide range of variation: Zawadzki (1996) found values from 11.45 to 19.23% in three species of the genus Hypostomus (Iguaçu River); Revaldaves et al (1997) observed 33.3% for Prochilodus lineatus (Paraná River) and Almeida and Sodré (1998) observed values from 6.67 to 20% in three Pimelodidae species (Tibagi River). Ward et al (1992) estimated an He value of 0.051 for about 150 marine and fresh water fish species.…”
Section: In Four Leporinus Species (Including L Friderici)mentioning
Genetic variability was studied in five fish species (Anostomidae): Schizodon intermedius and S. nasutus and Leporinus friderici, L. elongatus and L. obtusidens, collected at one location on the Tibagi River (Paraná, Brazil). The protein data from seven systems coded collectively for 19 loci in the liver, muscle and heart. Nine of these loci were polymorphic. The estimated proportion of polymorphism loci (P) varied from 16.7% in S. intermedius to 36.9% in L. friderici; the mean heterozygosity observed (Ho) was 0.027 ± 0.015 and 0.109 ± 0.042, respectively. The estimated value of the genetic identity among L. friderici and S. intermedius (0.749) and S. nasutus (0.787) suggested that these are "congeneric" species. Morphological characteristics indicate that these species belong to distinct genera, while isoenzymatic data show that they are very similar at the genetic/biochemical level.
“…Marine fish populations have fewer barriers to gene flow and usually show less genetic differentiation than freshwater fishes (Gyllensten, 1985;Ward et al, 1994). Some migratory freshwater fish species such as P. lineatus (Revaldaves et al, 1997;Sivasundar et al, 2001) and P. corruscans (Sekine et al, 2002) show low genetic differentiation while poorly migratory or resident species such as H. malabaricus show high genetic differentiation (Dergam et al, 1998).…”
Section: Resultsmentioning
confidence: 99%
“…The wide geographical range of H. regani not only contrasts with the narrow distribution of most Hypostomus species but can also raise doubts about the conspecificity of H. regani populations. Studies of the genetic population structure of Neotropical fish have mainly focused on known migratory species such as Prochilodus lineatus (Characiformes, Prochilodontidae) (Revaldaves et al, 1997) and Pseudoplatystoma corruscans (Siluriformes, Pimelodidae) (Sekine et al, 2002), with studies on nonmigratory fish having been restricted to Hoplias malabaricus (Characiformes, Erythrinidae) (Dergam et al, 1998;Peres et al, 2002). We have no data about migratory behavior of H. regani, whether it is resident, short, medium or long distance migratory.…”
Three Brazilian populations of the armored catfish Hypostomus regani (Ihering, 1905) were sampled, one from the Corumbá Reservoir in Goiás state, another from the Itaipu Reservoir in Paraná state and a third from the Manso Reservoir in Mato Grosso state. Allozyme electrophoresis was used to establish the genetic structure of the species, with the analysis of liver, heart and muscles tissues allowing the scoring of 25 loci from 14 enzymatic systems. Although no diagnostic loci were found, some exclusive rare alleles were recorded for the three populations. The genetically most similar populations were those from Corumbá and Itaipu, and the most distant were the populations from Manso and Corumbá. The allozyme data showed three structured populations belonging to the same species H. regani (F ST = 0.173).
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