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Abstract : |
Astyanax fishes are among the most important food-web components of South America rivers. In the Iguaأ§u River basin, the Astyanax genus is represented mainly by endemic species. For millions of years, that hydrographic basin has been geographically isolated from the Paranأ، River basin by the Iguaأ§u Falls. Recently, a species from the Upper Paranأ، River basin identified as Astyanax bimaculatus was revised and described as a new species named Astyanax altiparanae Garutti & Britski, 2000. Fauna endemism and geographic isolation triggered interest in investigations to evaluate the identification and genetic relatedness among two A. altiparanae populations from the Upper Paranأ، River basin and the population identified as A. bimaculatus in the Iguaأ§u River, upstream from the Iguaأ§u Falls. Mitochondrial DNA sequences and RAPD markers revealed high genetic diversity within each population, as well as low genetic distance, high gene flow, and high mitochondrial DNA similarity among all three populations. In conjunction with morphological similarities, these results demonstrated that the population presently known as Astyanax bimaculatus in the Iguaأ§u River should actually be stated as Astyanax altiparanae. Furthermore, it could be inferred that the A. altiparanae population is not endemic and most likely it was recently introduced in the Iguaأ§u River basin, maintaining the ancestral genetic identity., |
