Abstract
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 Tucunare 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 Parana basin. Different morphotypes in the region may also be due to hybridization. Current research used SPAR molecular markers to confirm the presence of hybrids and the rupture of isolation mechanisms. Seventy-two specimens collected in several sites of the river Parana and Amazon basins were analyzed. Since exclusive SPAR molecular markers were obtained for Cichla kelberi and C. piquiti populations, the introduction of the two species in the region has been confirmed. Identification of the markers in specimens of the Parana river basin confirmed hybridization between these exotic species.
Highlights
The introduction of species of fish in lacustrine ecosystems has been a prominent target in international literature, focusing on the studies that aim at evaluating the causes and effects of these introductions in native aquatic communities
The aim of this paper was to find molecular markers Single Primers Amplifications Reactions (SPAR) for the different Cichla species introduced in the Paraná river basin, besides obtaining data that corroborate the break of isolation mechanisms and the hybridization process already spoken, finding evidences of introgression of nuclear genes in the gene pool of both exotic species
The SPAR technique is being used for many searchers for identification of fish species, since that has been established a pattern of bands specific species (ALBERT et al, 1999; PRIOLI et al, 2004)
Summary
The introduction of species of fish in lacustrine ecosystems has been a prominent target in international literature, focusing on the studies that aim at evaluating the causes and effects of these introductions in native aquatic communities. The country has been receiving a high number of not native species of fishes (BUCKUP; MENEZES, 2003) and this introduction has been recognized as one of main direct causes of loss of biodiversity (AGOSTINHO et al, 2005). This practical has been carried out for increase of reservoirs fishing production, in grow of species appreciated by its taste and good development, for sportive intentions or accidentally, because of uninformation or escaping of tanks of fish culture. In the Brazilian Northeast, for example, species of the Cichla genus have been introduced, successfully, for increase of the reservoirs fishing production (CHELLAPPA et al, 2003)
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