Detection of two morphologically cryptic species from the cursor complex (Akodon spp; Rodentia, Cricetidae) through the use of RAPD markers.

The cursor complex is a group within the Akodon genus of South American rodents, formed by Akodon cursor and A. montensis. Correct distinction between these two species is of great importance since they can harbor different Hantavirus strains. These species are only distinguishable by means of karyotypic or internal anatomic features, requiring dissection; recently, some other genetic methods have become available. We developed RAPD markers capable of distinguishing between A. cursor and A. montensis. Samples included 42 individuals of A. cursor from four localities and 16 individuals of A. montensis from two localities. Fifty-five bands, 41 of which were polymorphic, were analyzed. A principal component analysis showed that this set of markers could successfully distinguish between the two species, mainly based on three RAPD bands. The number of bands in each population was compared within a 95% confidence interval as a measure of intraspecific variability. The A. cursor populations were found to have marked genetic structure across the study area (AMOVA; F(ST )= 0.21), which in part might be because of the relatively limited dispersal capabilities of this species. Species-specific bands, with potential for species identification, were identified.

Isolation and characterization of microsatellite DNA in the piracema fish Prochilodus lineatus (Characiformes).

We described five novel microsatellite loci for the piracema fish species Prochilodus lineatus (Characiformes), endemic to South America and of extreme importance to both commercial and artisanal fisheries across its occurrence area. A primary, unenriched genomic library was constructed and radioactively screened for repetitive motifs. Positive clones were automatically sequenced and based on the design of new primers, polymerase chain reaction assays were carried out to determine optimum reaction and electrophoretic conditions for each characterized locus. We evaluated its usefulness in population genetic studies by determining Hardy-Weinberg equilibrium, FIS and a jackknife estimate of the number of alleles for a sample of fish caught below the Funil Hydroelectric Power Plant dam (N = 95), Grande River, Brazil. The number of alleles varied from 3 to 21 and expected heterozygosities ranged from 0.58 to 0.91. Two of five loci were in Hardy-Weinberg equilibrium. Jackknife estimates of the number of alleles were higher than the observed number of alleles for three loci and could provide a measure of sampling bias. These markers should provide important tools for the determination of genetic structure, stock delimitation and reservoir fish management in the Grande River as well as to improve hatchery practices for environmental mitigation measures and to help sustain fisheries in the river.

Isolation and characterization of microsatellite DNA in the piracema fish Prochilodus lineatus (Characiformes)

We described five novel microsatellite loci for the piracema fish species Prochilodus lineatus (Characiformes), endemic to South America and of extreme importance to both commercial and artisanal fisheries across its occurrence area. A primary, unenriched genomic library was constructed and radioactively screened for repetitive motifs. Positive clones were automatically sequenced and based on the design of new primers, polymerase chain reaction assays were carried out to determine optimum reaction and electrophoretic conditions for each characterized locus. We evaluated its usefulness in population genetic studies by determining Hardy-Weinberg equilibrium, FIS and a jackknife estimate of the number of alleles for a sample of fish caught below the Funil Hydroelectric Power Plant dam (N = 95), Grande River, Brazil. The number of alleles varied from 3 to 21 and expected heterozygosities ranged from 0.58 to 0.91. Two of five loci were in Hardy-Weinberg equilibrium. Jackknife estimates of the number of alleles were higher than the observed number of alleles for three loci and could provide a measure of sampling bias. These markers should provide important tools for the determination of genetic structure, stock delimitation and reservoir fish management in the Grande River as well as to improve hatchery practices for environmental mitigation measures and to help sustain fisheries in the river.