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Made in Brazil: new evidence for anthropogenic dispersal of the brazil nut (Bertholletia excelsa, Lecythidaceae) in ancient Amazonia

Glenn Shepard Jr. (accredited professor, Instituto Nacional de Pesquisas da Amazonia (INPA))
Rogerio Gribel (Instituto Nacional de Pesquisas da Amazonia)
Maristerra Lemes (Instituto Nacional de Pesquisas da Amazonia)

Abstract

The Brazil nut, a colossal tree of upland primary forest, is the most important non-timber forest product of Amazonia. Its peculiarly inefficient seed dispersal strategy and discontinuous distribution in groves throughout Amazonia have lead some to hypothesize anthropogenic origins, but evidence to date has been inconclusive. Here we present results of a multidisciplinary study addressing this question. Genome sequencing of eight widespread Brazil nut populations (up to 2800 km apart) revealed no variation for six non-coding cpDNA regions, some of which show polymorphisms even at local scales for related Lecythis species. Eight polymorphic microsatellite markers showed no geographical structuring (93% of variation is contained WITHIN populations), further suggesting rapid and geologically recent irradiation from an ancestral population, most likely by humans. Comparative linguistic analysis and ecological and ethnographic observations reinforce the hypothesis that ancient Amazonian peoples played a key role in establishing this emblematic and economically important rainforest landscape.