Genomic analyses reveal the vital role of human activity in the Amazonian species’ genetic makeup.

Researchers from the German Max Planck Institutes of Geoanthropology and Biology Tübingen use genomic data to study the decline in genetic diversity in the Amazon Basin, particularly in Brazil Nut trees. The research uses genomic data to understand this keystone species’ genetic health and adaptability, help reconstruct its demographic history, and assess the long-term impacts of human interaction on forest ecosystems. The findings emphasise the need for conservation strategies to consider both ecological and anthropogenic factors.

The significant decline in genetic diversity in the Amazon Basin, following historical events such as European colonisation, deforestation and the extinction of species such as the sloth – the main seed dispersal agents, is of particular concern for the genetic health of Brazil Nut trees (Bertholletia excelsa). As one of the most impacted keystone species in rainforests, Brazil Nut trees are essential for biodiversity and a vital income source for local economies.
A new study led by researchers from the Max Planck Institute of Geoanthropology and the Max Planck Institute for Biology Tübingen unveils critical insights into the species' genetic diversity and population dynamics, providing valuable anthropogenic and biological information for this threatened forest ecosystem.
“This research provides an amazing opportunity to study see how human actions, even in the distant past, have affected genetic makeup in a wild species over short time scales,” states Detlef Weigel, director of the Department of Molecular Biology at the Max Planck Institute for Biology Tübingen.

Genomic analyses reveal the importance of Indigenous management practices

Using advanced genomic techniques, the researchers comprehensively analysed samples from 270 Brazil Nut trees growing in areas with differing instensitites of archaeological evidence. The study provides detailed genomic data, including identifying over 126,000 genetic variants in Brazil Nut, revealing valuable insights into the genetic structure, gene flow and adaptability of the species in the face of environmental changes.

The findings indicate that while the genetic diversity of Brazil Nut has drastically declined over the last 20,000 years compared to other species, areas with a history of Indigenous management show more complex genetic backgrounds. In these areas, evidence for improved gene flow and regeneration from long-term traditional human management is linked to increased genetic diversity. In particular, younger trees in the protected Tefé National Forest (TEF), estimated to be under 200 years old, exhibit complex genetic backgrounds compared to other studied groups, likely due to the interplay of natural disturbances and local communities’ management. This genetic diversity is crucial for the species’ resilience and adaptability in the face of environmental changes.
Victor Caetano-Andrade, Postdoctoral researcher in the Department of Coevolution of Land Use and Urbanisation at the Max Planck Institute of Geoanthropology, explains, “We aimed to bridge gaps in our understanding of the long-term anthropogenic influences on forest ecosystems. Our findings demonstrate how Indigenous land management practices play a significant role in maintaining the genetic diversity of Brazil nut populations.”
As evidence for the effectiveness of traditional ecological practices accumulates, not only in supporting genetic diversity but also in managing fire regimes, scholars and policy makers increasingly recognize the importance of Indigenous knowledge. Promoting collaboration between scientists and local Indigenous land stewards has the potential to create more effective and inclusive conservation policies.
Looking ahead, the researchers plan to expand their studies to include more regions and additional species within the Amazon rainforest. The goal is to develop comprehensive conservation frameworks that protect Brazil Nut trees and enhance the ecosystem's resilience.

This content is taken from Max Planck Institute of Geoanthropology

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"How human activity has shaped Brazil Nut forests’ past and future", MachPrinciple, August 02, 2025, https://machprinciple.com/post/How-human-activity-has-shaped-Brazil-Nut-forests-past-and-future1688db8e4efe84