Environmental genomics of Late Pleistocene black bears and giant short-faced bears

Analysis of ancient environmental DNA (eDNA) has revolutionized our ability to describe biological communities in space and time,1–3 by allowing for parallel sequencing of DNA from all trophic levels.4–8 However, because environmental samples contain sparse and fragmented data from multiple individuals, and often contain closely related species,9 the field of ancient eDNA has so far been limited to organellar genomes in its contribution to population and phylogenetic studies.5,6,10,11 This is in contrast to data from fossils12,13 where full-genome studies are routine, despite these being rare and their destruction for sequencing undesirable.14–16 Here, we report the retrieval of three low-coverage (0.03×) environmental genomes from American black bear (Ursus americanus) and a 0.04× environmental genome of the extinct giant short-faced bear (Arctodus simus) from cave sediment samples from northern Mexico dated to 16–14 thousand calibrated years before present (cal kyr BP), which we contextualize with a new high-coverage (26×) and two lower-coverage giant short-faced bear genomes obtained from fossils recovered from Yukon Territory, Canada, which date to ∼22–50 cal kyr BP. We show that the Late Pleistocene black bear population in Mexico is ancestrally related to the present-day Eastern American black bear population, and that the extinct giant short-faced bears present in Mexico were deeply divergent from the earlier Beringian population. Our findings demonstrate the ability to separately analyze genomic-scale DNA sequences of closely related species co-preserved in environmental samples, which brings the use of ancient eDNA into the era of population genomics and phylogenetics. [Display omitted] •We recovered genomic data from ancient bears directly from cave sediments•Ancient Mexican black bears are ancestrally related to Eastern American black bears•The Mexican and Yukon populations of extinct giant short-faced bears were distinct•Our results bring ancient eDNA into the era of population genomics To date, ancient eDNA has been limited to simple taxonomic profiling of biological communities rather than population or phylogenetic studies. Using genome-wide analysis of American black bear and giant short-faced bear DNA extracted from cave sediments, Pedersen et al. show that population genomics is now possible using ancient eDNA.