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bioRxiv · 10.1101/2025.09.01.673595

Ancient bridges, modern threat: Conserving landscape heterogeneity ensures sustenance of living root-bridges in Meghalaya

Ghosh, T.·Ramakrishnan, U.·Borges, R. M.
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Abstract

The Anthropocene, marked by rapid biodiversity loss, has renewed attention on natures contributions to people, which include ecological, cultural, and spiritual values. A striking example of such nature-culture interactions are the living root-bridges of Meghalaya, India, where Khasi people ingeniously train the aerial roots of Ficus elastica across river valleys to form natural bridges. These structures, currently under consideration for UNESCO World Heritage recognition, exemplify sustainable resource use in one of the wettest and most landslide-prone regions of the world. However, increasing tourism and unregulated construction is threatening to this nature culture relationship in a biodiversity hotspot. In such situations, understanding the factors governing the geneflow is vital to the preservation of interactions between the pollinating fig wasps, the fig tree and its seed dispersers. Despite its ecological and cultural significance, little is known about the population biology or dispersal potential of F. elastica. Here, we investigated dispersal potential of natural populations of F. elastica across Meghalaya. Using ddRAD-SNP genotyping ([~]12K SNPs from 308 individuals), we detected four genetic clusters corresponding to E. Khasi, W. Khasi, W. Jaintia, and Ribhoi hills. Redundancy analysis and resistance modelling revealed that wind regimes and topography jointly structure these populations, enabling gene flow within but not across river valleys. Analysis of spatial distribution of related individuals indicates short dispersal distance of 1-4km varying across different populations. Given F. elasticas association with riparian ecosystems, and with UNESCO recognition pending, our study underscores the need for strict guidelines to curb habitat destruction and ensure the long-term survival of both the species and its cultural legacy.

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Ghosh, T., Ramakrishnan, U., Borges, R. M.. 2025-09-03. Ancient bridges, modern threat: Conserving landscape heterogeneity ensures sustenance of living root-bridges in Meghalaya. https://doi.org/10.1101/2025.09.01.673595

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