Unexpected fish diversity gradients in the Amazon basin

Thierry Oberdorff, Murilo S. Dias, Céline Jézéquel, James S. Albert, Caroline C. Arantes, Rémy Bigorne, Fernando M. Carvajal-Valleros, Aaike De Wever, R. G. Frederico, Max Hidalgo, Bernard Hugueny, Fabien Leprieur, Mabel Maldonado, Javier Maldonado-Ocampo, Koen Martens, Hernan Ortega, Jaime Sarmiento, Pablo A. Tedesco, Gislene Torrente-Vilara, Kirk O. WinemillerJansen Zuanon

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102 Scopus citations


Using the most comprehensive fish occurrence database, we evaluated the importance of ecological and historical drivers in diversity patterns of subdrainage basins across the Amazon system. Linear models reveal the influence of climatic conditions, habitat size and sub-basin isolation on species diversity. Unexpectedly, the species richness model also highlighted a negative upriver-downriver gradient, contrary to predictions of increasing richness at more downriver locations along fluvial gradients. This reverse gradient may be linked to the history of the Amazon drainage network, which, after isolation as western and eastern basins throughout the Miocene, only began flowing eastward 1–9 million years (Ma) ago. Our results suggest that the main center of fish diversity was located westward, with fish dispersal progressing eastward after the basins were united and the Amazon River assumed its modern course toward the Atlantic. This dispersal process seems not yet achieved, suggesting a recent formation of the current Amazon system.

Original languageEnglish
Article numbereaav8681
JournalScience advances
Issue number9
StatePublished - 11 Sep 2019

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