The authors analyzed patterns of similarity of RAPD-PCR genomic markers of samples …

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• Materials and Methods
• Results
• Discussion
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Biology Articles » Biogeography » Molecular biogeography of the Neotropical fish Hoplias malabaricus (Erythrinidae:Characiformes) in the Iguaçu, Tibagi, and Paraná Rivers » Introduction

Introduction

- Molecular biogeography of the Neotropical fish Hoplias malabaricus (Erythrinidae:Characiformes) in the Iguaçu, Tibagi, and Paraná Rivers

Knowledge of geographical distribution patterns of freshwater fish in the Neotropical Region is still quite scarce. Research is complicated by insufficient sampling, poor accessibility of type material, and high levels of diversity of the fish fauna of this region (Böhlke et al., 1979). This is the case for the characin Hoplias malabaricus (Bloch, 1794), which has considerable morphological variation among and within populations (Eigenmann and Eigenmann, 1889) making it difficult to determine the origin of the recently established population in the Iguaçu River (southeastern Brazil) (Figure 1).

The basin of the Iguaçu River extends from the western slope of a coastal relief, Serra do Mar, to the Paraná River, along with several other rivers including the Tibagi and Ivaí. The Iguaçu is isolated from the Paraná River by the Iguaçu falls. These falls date from the Oligocene (Sampaio, 1988). The fall of approximately 100 m constitutes a formidable barrier for upstream dispersal of fish fauna of the Paraná into the Iguaçu. This long term isolation certainly played a critical role in the endemism of fish fauna of the Iguaçu, which was considered by Haseman (1911) as its most remarkable feature.A recent survey by the limnology research group (NUPELIA) of the Universidade Estadual de Maringá identified 52 fish species in the Iguaçu River (FUEM/NUPELIA/COPEL, 1995), 75% of which were considered endemic, 17% indigenous but not endemic, and 8% introduced.

Haseman (1911) reported the absence of H. malabaricus in the Iguaçu River, while Godoy (1979) gave the first published account of its presence. Locals assert that H. malabaricus was likely introduced during the last decades, perhaps during aquaculture stocking of other exotics such as carp and tilapia (Sampaio, 1988). These exotics are also established in the Iguaçu (FUEM/NUPELIA/COPEL, 1995).

To unravel the question of the origin of the Iguaçu River population of H. malabaricus, we analyzed patterns of variation of nuclear markers of one sample from the Iguaçu, and six samples from two neighboring basins. This information may be relevant for preventing (or explaining) invasions of other species of exotic fishes in the Iguaçu, as well as for future assessments of the degree of endemism of the Iguaçu River fish fauna.