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 ~10,000 years, as well as interactions with the local plant community. We document a dynamic history of beaver presence in two subalpine 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 7200 years BP and intermittently thereafter. At nearby Taggart Lake, beavers were first detected at ~5900 years BP and continuously from 5200 years BP onward. Vegetation metabarcoding revealed a shift in plant community coinciding with beaver establishment in these two subalpine lakes, as well as an increase in taxonomic diversity. These changes coincide with regional trends toward 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 robust time series data of historical beaver occupancy dynamics.