Sedimentary ancient DNA and the Palaeoecology of the Late Quaternary Extinctions

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Today, we are witnessing an acceleration of climate warming with potential environmental impacts unprecedented in the last 10,000 and perhaps even 125,000 years. Changes in artic and subarctic environments are largely exceeding those predicted, making the long-term effects of these changes on the macro (i.e. faunal, flora and insect community composition) and micro (i.e. bacteria, fungi and viruses) levels, a challenge to robustly model or predict. Here we propose to use ancient environmental DNA recovered from lake sediments and permafrost cores to closely track shifting ecological signatures in northwestern North America over the last ~25,000 years to disentangle long-term climate and ecological trends from the comparatively rapid peopling of the Americas. We will develop novel methodology and targeting strategies to enrich ecologically diagnostic palaeoenvironmental ancient biomolecules (DNA, proteins, RNA) from plants, fungi, animals, and microbiota to correlate with other multi-proxy indicators of ecological change, vertebrate restructuring, and archaeological mobility to holistically assess how and why terrestrial ecosystems trophically downscaled at end of the last ice age. Ancient biomolecules are transforming our ability to critically evaluate environmental and biotic change over intervals ranging from a few decades to hundreds of thousands of years. And there are few places on Earth where the need for such information is more vital than our warming Arctic, especially because the detection and assessment of trends now affecting the far north have potentially global significance. For this intent a baseline through previous climatic cycles (no anthropogenic forcing) is needed, against which change and its consequences can be reliably measured and compared. In this NSERC grant we intend to take our work an important step forward, by concentrating on developing and exploiting novel methodologies for fine-scale resolution of paleoecological change in well-calibrated, geologically significant sedimentary deposits (i.e. permafrost and lake sediments). We intend to work at all accessible levels, including not only floral and faunal studies but also previously untapped resources such as microbial community structure and pathways underlying active biogeochemical cycling. The short term-objectives outlined below will enable us to track, at unprecedented depth, how biodiversity was restructured in selected high-latitude and high-altitude areas of the Americas, through the Pleistocene/Holocene transition (~20,500-8,300 bp), an interval that witnessed with numerous megafaunal extinctions amid shifting influences from a changing climate, ecological reconfigurations, and ultimately anthropogenic forcing.