Sedimentary ancient DNA and the Palaeoecology of the Late Quaternary Extinctions

今天，我们正在目睹气候变暖的加速，潜在的环境影响在过去10,000年甚至可能是125,000年来都是前所未有的。北极和亚北极环境的变化在很大程度上超过了预测，这使得这些变化对宏观(即动物、植物群和昆虫群落组成)和微观(即细菌、真菌和病毒)水平的长期影响成为一个强有力的模型或预测的挑战。在这里，我们建议使用从湖泊沉积物和永久冻土岩芯中恢复的古代环境DNA来密切跟踪北美西北部过去约25,000年来生态特征的变化，以将长期气候和生态趋势与美洲相对快速的人口增长区分开来。我们将开发新的方法和目标策略，以丰富来自植物、真菌、动物和微生物群的生态诊断古环境古生物分子(DNA、蛋白质、RNA)，以与生态变化、脊椎动物重组和考古流动性的其他多指标相关联，以全面评估陆地生态系统如何以及为什么在上一次冰河时代结束时营养缩减。古老的生物分子正在改变我们批判性地评估环境和生物变化的能力，时间间隔从几十年到数十万年不等。地球上很少有地方比我们正在变暖的北极更需要这样的信息，特别是因为检测和评估目前影响远北的趋势具有潜在的全球意义。为了达到这一目的，需要通过以前的气候周期(不需要人为强迫)确定基线，对照这个基线，可以可靠地衡量和比较气候变化及其后果。 在NSERC的这笔赠款中，我们打算通过集中开发和开发新的方法来推动我们的工作向前迈出重要的一步，以精细地解决校准良好的、具有地质意义的沉积沉积物(即永冻土和湖泊沉积物)中的古生态变化。我们打算在所有可获得的层面上开展工作，不仅包括动植物研究，而且还包括以前未开发的资源，如微生物群落结构和活跃的生物地球化学循环的途径。下面概述的短期目标将使我们能够以前所未有的深度追踪美洲选定的高纬度和高海拔地区的生物多样性是如何通过更新世/全新世过渡(约20,500-8,300 BP)进行重组的，在这段时间里，由于气候变化、生态重组和最终的人为强迫的影响，见证了许多大型动物的灭绝。

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.