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Hydromedusa maximiliani is a vulnerable neotropical freshwater turtle endemic to mountainous regions …


Biology Articles » Genetics » Ecological Genetics » Estimating dispersal and gene flow in the neotropical freshwater turtle Hydromedusa maximiliani (Chelidae) by combining ecological and genetic methods » Introduction

Introduction
- Estimating dispersal and gene flow in the neotropical freshwater turtle Hydromedusa maximiliani (Chelidae) by combining ecological and genetic methods

The neotropical freshwater turtle Hydromedusa maximiliani (Chelidae) is endemic to the Atlantic forest of the coastal region of southeastern Brazil, with a geographical distribution ranging from the State of Espírito Santo to the State of São Paulo (Ernst and Barbour, 1989; Iverson 1992). Throughout its range, the distribution of H. maximiliani is disjunct, occurring in isolation at elevations above 600 m. Locally, its habitat is topologically complex, with sequences of ridges and valleys each drained by river and stream systems (Souza, 1995).

Capture-recapture studies have shown that these turtles have limited dispersal ability, with a mean daily displacement of 2 m (Souza 1995; Souza and Abe, 1997a). Dispersal over longer distances is apparently limited to the rainy season, when temporary or intermittent water systems are connected with the main watercourses (Souza and Abe, 1997a). The observed limited dispersal suggests that each H. maximiliani population inhabits a specific river within a given drainage system, and this hypothesis was addressed in a preliminary work on the population genetic structure of the species, which indicated a substantial partitioning of molecular variation across rivers and streams inhabited by this turtle (Souza et al., 2002). These findings of population structure on a small spatial scale defined by the complex topographical features of the species habitat, a region topologically complex, with ridges and valleys drained by numerous rivers and streams (Pfeifer et al., 1986; Souza and Abe 1998), could imply that there is little or no gene flow among turtles inhabiting different water courses or distinct drainage. In this study, we used random amplified polymorphic DNA (RAPD) markers (Williams et al., 1993) to assess levels of gene flow among local H. maximiliani populations, and briefly discuss the conservation and management implications of our findings.


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