Não informado.

Author(s)

Fernanda Simões de Almeida

• Document type: Doctoral Thesis
• Press: Ribeirão Preto. , gráficos, ilustrações, tabelas.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2003-04-22

Examining board members

Eucleia Primo Betioli Contel; Ricardo Macedo Corrêa e Castro; Fausto Foresti; Alberto José Prioli; Leda Maria Koelblinger Sodré

• Advisor: Eucleia Primo Betioli Contel
• Field of knowledge: Biological Sciences - Genetics
• Indexed in: Banco de Dados Bibliográficos da USP-DEDALUS
• Location: Universidade de São Paulo. Biblioteca Central do Campus de Ribeirão Preto; FMRP/Almeida, Fernanda Simões de

Abstract

The family Pimelodidae, to which the genus Pimelodus belongs, presents great economical importance as alimentary supply. The systematics of the family has been the objective of several studies for a better understanding of its classification. RAPD and rDNA 5S were used to study the genetic structure of Pimelodus species collected in five different rivers from the Paraná basin, and to accomplish a comparative analysis with species collected in Paraguay, Uruguay and Paraíba do Sul rivers basins. The species Pimelodus maculatus was analyzed in 4 rivers of the Paraná basin (Tietê, Paranapanema, Paraná e Tibagi); the population from the Paraná river showed the smallest genetic variability and the population from the Tibagi river the largest. All the populations were genetically structured according to the Theta test. The obtained dendrogram pointed to a grouping tendency among the individuals of each one of the subpopulations. P. heraldoi from the Tibagi river and P. ortmanni and Pimelodus sp from the Iguaçu river presented levels of polymorphism similar to the obtained for P. maculatus. Considering these tree species only P. heraldoi did not present evidence for genetic structuring. Pimelodus sp showed a tendency for genetic structuring as indicated by the genetic as well as the dendrogram analyses. P. ornatus from the Paraná river presented the smallest genetic variability among all the analyzed species, which may be explained by the fact that this species was collected in only one location from high Paraná river basin. Regarding electrophoretic patterns of RAPD, two different ones were observed among P. maculatus individuals, which were interpreted as belonging to different species. The comparative analysis between P. absconditus (Miranda river) and P. heraldoi (Tibagi river) indicates a great genetic identity among them although other data suggest that they may be considered as different species. Comparisons among P. maculatus\' individuals from different basins showed that only the Miranda river population (Paraguay river basin) is genetically different from the others, suggesting that it could be considered a new species. The use of genetic and morphometric data to compare Miranda river species (P. maculatus, P. argenteus and Pimelodus sp) and high Paraná river species (P. maculatus from Porto Primavera and Jupiá) indicated a great similarity between P. maculatus from Porto Primavera (Paraná river basin) and Pimelodus sp from Miranda river. We do suggest that these might be considered as the same species. The data also suggest that P. ornatus would belong to a different genus. (AU)