Ancient sedimentary DNA shows more than 5000 years of continuous beaver occupancy in Grand Teton National Park

Beaver-based restoration is emerging as a cost-effective conservation and climate adaptation strategy, but efforts are constrained by limited knowledge of pre-colonial beaver distribution and their long-term ecosystem impacts. Here, we apply sedimentary ancient DNA (sedaDNA) techniques to investigate the history of beaver occupancy at three lakes in Grand Teton National Park, Wyoming over the last ∼10 ka, as well as interactions with the local plant community. We documented a dynamic history of beaver presence in two sub-alpine lakes (Taggart and Jenny Lakes) and demonstrate no history of beaver occupancy at the higher-elevation alpine lake (Lake Solitude). Beavers were first detected at Jenny Lake around 7.2 ka and intermittently thereafter. At nearby Taggart Lake, beavers were first detected at ∼5.9 ka and continuously from 5.2 ka onwards. Vegetation metabarcoding revealed a shift in plant community coinciding with beaver establishment in these two sub-alpine lakes, as well as an increase in taxonomic diversity. These changes coincide with regional trends towards wetter conditions. Notably, beavers persist at Taggart Lake during inferred droughts, indicating a potential role in maintaining wetlands through extended periods of climatic stress. Our results demonstrate sedaDNA as a powerful, novel technique for reconstructing past beaver occupancy dynamics.