Beringian flora and fauna from sedaDNA at Duvanny Yar, Sakha Republic, during marine isotope stages 2 and 3

Beringia’s extensive late Quaternary deposits of yedoma silt provide rich floristic and faunal records. Sampling of frozen yedoma exposures typically uses multiple baydzherakhs (residual silt heaps developed as conical thermokarst mounds) that collectively straddle vertical and horizontal space in thaw slumps. We used radiocarbon-dated vertical and horizontal transects to assess stratigraphic and sampling consistency at Duvanny Yar (a critical late Pleistocene stratotype). Most samples are ascribed to later marine isotope stage (MIS) 3 or to MIS 2 (ca. 40,000 to 20,000 years ago). The horizontal (MIS 3) transect revealed an undulating paleolandscape. Sedimentary ancient DNA (sedaDNA) from frozen yedoma revealed floristic composition in time and space. Metabarcoding and shotgun metagenomic molecular floras and pollen spectra are ecologically consistent. Floristically, little separates MIS 3 and 2; xeric, treeless vegetation, dominated by grasses and forbs including disturbance indicators, characterizes both stages. Holocene samples have a distinct, woody-dominated flora. Ordination of metabarcoding samples from the horizontal transect shows samples are highly variable but do not form a discernible spatial gradient or mosaic, possibly reflecting microtopographically driven plant distribution across a largely homogeneous landscape. Mammals identified from MIS 3 and 2 include horse, steppe bison, woolly rhinoceros, woolly mammoth, reindeer, hare, and vole.