Latest Pleistocene shrub expansion and steppe-tundra persistence in easternmost Beringia

The collapse of the mammoth steppe ecosystem at the end of the Pleistocene fundamentally restructured northern communities across Beringia, yet the spatial variability of this transition remains poorly understood. We present a multi-proxy analysis of the Mint Gulch site in the Klondike region, Yukon Territory, spanning ca. 16,000 to 13,000 calibrated years before present (cal yr BP), integrating sedimentary ancient DNA (sedaDNA), macrofossils, pore-ice isotopes (δ18O), and radiocarbon chronology. Pore-ice isotope values increase from −33.9‰ at ca. 16,000 cal yr BP to −21.4‰ by ca. 13,180 cal yr BP, reflecting regional warming and changing hydroclimate. SedaDNA records document grazing megafauna (woolly mammoth, horse, steppe-bison) and grasses and forbs until ca. 13,910 cal yr BP, when shrub-dependent taxa and browsing herbivores (moose, willow ptarmigan) first appear, or appear in greater abundance. However, macrofossil evidence from an Arctic ground squirrel midden (ca. 13,680 cal yr BP) reveals continued presence of steppe-tundra indicator taxa, including Artemisia sp., Potentilla sp., and the weevil Connatichela artemisiae. Our results demonstrate that despite regional hydroclimate change beginning ca. 14,000 cal yr BP, steppe-tundra vegetation persisted in locations where topography and aspect favoured xeric taxa. The Mint Gulch site provides rare documentation of the transitional period between steppe-tundra and shrub-tundra ecosystems, capturing co-occurrence of both communities around 13,910 cal yr BP. This study highlights the spatially heterogeneous nature of late Pleistocene ecosystem transitions in eastern Beringia and the importance of multi-proxy approaches for understanding local-scale persistence of steppe-adapted taxa.