| The introduction of exotic species in lake ecosystems has been greatly highlighted in the literature worldwide. Since introduction may threaten diversity of native fish, the issue turns up to be of paramount importance. Ecological effects may be predation, competition, parasitism or genetic, that is, changes in the genetic pool of populations owing to the occurrence of hybrids. Although the Tucunaré fish (Cichla) is native to the Amazon region, it can be found in other hydrographic basins in which it has been introduced. RAPD molecular marker research showed that there are two species (Cichla kelberi and C. piquiti) belonging to the genus Cichla in the rivers of the Paraná basin. Different morphotypes in the region may also be due to hybridization. Current... |
