Comparative Phylogeography and Patterns of Diversification
of Amazonian Fishes

The world's highest biodiversity is found in the lowland forests of Amazonia. Despite its enormous importance as a source of biodiversity, little is known about the evolutionary processes that generate diversification in Amazonia. This is particularly true for the extremely diverse and understudied Amazonian fish fauna. We are using powerful analyses of DNA data to elucidate the diversification of fishes from the Rio Negro floodplain (RNF), in central Amazonia. So far, we have explored over 2,200 km of flooded forests and sampled ~ 100 codistributed populations of four species groups of forest fish (Paracheirodon axelrodi, Nannostomus unifasciatus, Carnegiella martae and Hemigrammus bleheri).

The RNF covers an area of 0.75 million km2 of largely undisturbed primary forests. The unspoiled status of the RNF can be partly attributed to a thriving ornamental fishery that provides about 60% of the income of local riverine people. This study is linked to Project Piaba (piaba is the local name for small fish), a community-based interdisciplinary project established over ten years ago by Prof. Chao (Univ. do Amazonas, Brazil). That project aims to understand the ecological and socio-cultural systems of middle RNF for maintaining the ornamental fishery at commercially and ecologically sustainable levels. We will combine genetic with fishery data to identify conservation units and propose appropriate management strategies for the ornamental resources.

This project is genrating one of the largest molecular data sets for codistributed tropical rainforest species. For each of the ~ 2,000 individuals samples we are collecting data from microsatellite DNA markers, mtDNA and nuclear introns. Our data set will be analysed based on a statistical framework that will (i) describe and compare genetic and phylogeographic structure and (ii) estimate the chronology of evolutionary factors compatible with genetic patterns observed in extant populations. This will probably enable us to evaluate the relative contribution of ecological and geographic processes underlying population differentiation and population history and test multiple hypotheses about speciation in tropical rainforests. The project should make a significant contribution to understanding biological differentiation in the tropics, a topic that has challenged biologists for over 150 years.

Click here for photographs of our field expeditions to Amazonia

Selected publications

Beheregaray LB, Möller LM, Schwartz TS, Chao NL, Caccone G (2004) Microsatellite markers for the cardinal tetra Paracheirodon axelrodi, a commercially important fish from central Amazonia. Molecular Ecology Notes 4, 330-332.

Beheregaray LB, Schwartz TS, Möller LM, Call D, Chao NL, Caccone G (2004) A set of microsatellite DNA markers for the one-lined pencilfish Nannostomus unifasciatus, an Amazonian flooded forest fish. Molecular Ecology Notes 4, 333-335.

Beheregaray LB, Chae J, Chao NL, Caccone G (2005) Characterization of microsatellite loci for the rummy nose tetra Hemigrammus bleheri (Characidae), an Amazonian flooded forest fish. Molecular Ecology Notes.

Beheregaray LB, Piggott M, Chao NL, Caccone G (2006) Development and characterization of microsatellite markers for the Amazonian blackwing hatchetfish, Carnegiella marthae (Teleostei, Gasteropeloecidae). Molecular Ecology Notes 6, 787-788.

Cooke GM, Beheregaray LB (2007) Extremely high variability in the S72 intron of the Amazonian cardinal tetra (Paracheirodon axelrodi). Journal of Fish Biology. In press.