Metagenomic insights into the diet and past Kolyma Lowland habitat from the intestinal content of a Late Pleistocene steppe bison

During the last cold stage (115–11.7 cal kya BP), the non-glaciated part of Arctic Eurasia exhibited a distinctive plant composition consisting of steppe and xerophilous arctic plants. This vegetation formed the Pleistocene mammoth steppe, which provided a habitat for large herbivores like mammoths (Mammuthus primigenius) and steppe bison (Bison priscus). In this study, we analyzed the DNA sequences of well-preserved plant material from the intestinal tract of the frozen mummy of an extinct steppe bison discovered in the Kolyma Lowland, Northeastern Russia in 2009. Radiocarbon dating placed the specimen at >48 kyr. We leveraged genome-wide and skimmed genome accessions to maximize the retrieval of sequenced reads for identification. In line with macrofossil evidence, we identified alkali grass (Puccinellia), indicating high salinity, and Larch (Larix) in the DNA data of the steppe bison sample. The occurrence of larch north of the current tree line indicates warm temperatures during the growing season. Additionally, we confirmed the presence of plant genera typically associated with steppes and productive meadows under open and arid soil conditions such as Artemisia, Tanacetum, Koeleria, Festuca, Puccinellia, Taraxacum, Alopecurus, and Poa, while Phippsia suggests high soil water content, at least locally. We also attempted to infer the likely most closely related species for each genus. The most abundant authenticated genera, Artemisia and Puccinellia, align with their known prevalence in the mammoth steppe, reflecting broader environmental signals beyond the steppe bison's diet. Hence, the use of metagenomic approaches in combination with comprehensive reference databases offered insights into steppe bison diet, allowed us to obtain a more detailed view of the mammoth steppe vegetation, and provided extended interpretations of soil conditions.