Giselle Xavier Perazzo

Trends of karyotypical evolution in the pearl cichlid, Geophagus brasiliensis, from southern Brazil

Chromosomal rearrangements such as inversions can facilitate speciation even in the presence of gene flow. The present study aims to analyze the karyotypic variation in six populations of Geophagus brasiliensis from southern Brazil. All specimens showed 2n=48 chromosomes, but three karyotypes were found to have one, two or three pairs of submetacentric chromosomes. Although G. brasiliensis did not exhibit variation in the diploid number, it presented a wide interpopulational variation mainly regarding the karyotype formula and specific chromosomal markers. Differences in the location of the major and minor rDNA loci were observed among the populations. Moreover, different patterns were observed in the distribution of the constitutive heterochromatin, presenting intra- and interpopulational variation. This supports the hypothesis that this taxon represents a complex species or that cryptic species are included in this group, indicating a possibleprocess of sympatric speciation. By potentially restricting gene flow between heterokaryotypes, the segregating chromosome rearrangements we describe for G. brasiliensis may play a role in diversification in this species complex.

Evaluating the copper water Uruguay river mutagenic potential

Analysis of Uruguay river water noted the presence of compounds at concentrations above the limits recommended by the brazilian legislation, such as the copp...

AQUATIC INSECTS BIOINDICATORS: INFLUENCE OF FISH FARM IN A STREAM OF BRAZILIAN PAMPA

Anthropic activities can cause alterations in physical, chemical and biological characteristics of aquatic ecosystems. Therefore, this work shows an assessment of water quality of a stream that receives fish farming effluents, using insects as bioindicators. Aquatic insects were sampled in summer and winter of 2012, in three sites (upstream – P01; in the effluent discharge site – P02; downstream – P03) of Felizardo Stream, Uruguaiana, Brazil. Network lock, drift nets and dip nets were used for insect capture, and aquatic physical-chemical parameters (temperature, dissolved oxygen, ammonia nitrogen, electric conductivity, and pH) were analyzed. In the summer, differences about family richness, abundance and density of specimens were observed, with the P02 site values lower than P01 and P03, and higher degree of dominance than P01 and P03. The physical-chemical parameters were in accordance with allowed values, according with legislation. However the biotic indices suggest the occurrence of direct influence of fish farming effluents in insect fauna in P02. Therefore, there is evidence of moderate effects of water pollution, or some organic pollution, according with these biotic indices. With these results, the waters of Felizardo Stream remain in the class II, even suffering influence of fish farming effluents.