Collapse of the mammoth-steppe in central Yukon as revealed by ancient environmental DNA

Abstract

The temporal and spatial coarseness of megafaunal fossil records complicates attempts to to disentangle the relative impacts of climate change, ecosystem restructuring, and human activities associated with the Late Quaternary extinctions. Advances in the extraction and identification of ancient DNA that was shed into the environment and preserved for millennia in sediment now provides a way to augment discontinuous palaeontological assemblages. Here, we present a 30,000-year sedimentary ancient DNA (sedaDNA) record derived from loessal permafrost silts in the Klondike region of Yukon, Canada. We observe a substantial turnover in ecosystem composition between 13,500 and 10,000 calendar years ago with the rise of woody shrubs and the disappearance of the mammoth-steppe (steppe-tundra) ecosystem. We also identify a lingering signal of Equus sp. (North American horse) and Mammuthus primigenius (woolly mammoth) at multiple sites persisting thousands of years after their supposed extinction from the fossil record.

The Coronavirus Calendar (CoronaCal): a Simplified SARS-CoV-2 Test System for Sampling and Retrospective Analysis

“…Physical anthropologists, forensic practitioners, and historical epidemiologists often obtain valuable data from materials that do not meet the standards of clinical diagnosis. Most nucleic acid recovery from non-optimal and ancient materials has been DNA [19]. However, the recovery of RNA sequences from the 1918-1919 influenza via paraffin sections and victims exhumed from permafrost graves [20] and HIV from lymph node embeds from 1960s [21] shows that RNA under at least some circumstances is more stable than often assumed.…”

“…In addition to records of individuals, related approaches would be valuable if applied to wastewater [24, 25] and eco-environmental contexts. Archived biological diaries from multiple levels would add rich information to retrospective reviews aimed at improving pandemic response [26], public health more generally[27] and enhancing understanding of our relentlessly evolving world[19, 28, 29].…”

Bottom-up versus top-down megafauna–vegetation interactions in ancient Beringia

“…Second, bone frequency may carry a complex relationship to megafaunal population abundance, given the vagaries of collection efforts and given that past environmental change may alter the likelihood of bone preservation. This study also does not leverage some of the newer proxies for megafaunal presence and function, including coprophilous fungal spore records ( 20 ) and ancient sedimentary DNA ( 21 ). Ancient DNA records hint at the persistence of at least small populations of mammoth and horse from the central Yukon as late as 6,000 y ago, long after the apparent disappearance of these animals from the bone record ( 21 ).…”

“…This study also does not leverage some of the newer proxies for megafaunal presence and function, including coprophilous fungal spore records ( 20 ) and ancient sedimentary DNA ( 21 ). Ancient DNA records hint at the persistence of at least small populations of mammoth and horse from the central Yukon as late as 6,000 y ago, long after the apparent disappearance of these animals from the bone record ( 21 ). These critiques are not serious—the Monteath et al.…”

Metagenomic analysis of coprolites from three Late Pleistocene megaherbivores from the Southwestern United States

“…Terrestrial ecosystems have lost a significant proportion of their megafauna (species > 44.5 kg) (Stuart 2015; Malhi et al 2016; Smith et al 2016; Smith and Lyons 2011; Smith et al 2018), with many of these extinctions occurring during the Late Pleistocene due to anthropogenic pressures (Smith et al 2019; Sandom et al 2014; Barnosky et al 2004) and climate change (Barnosky et al 2004; Mann et al 2019; Monteath et al 2021; Wang, Zhang, and Kong 2021). Studies have shown that such dramatic extinctions of megafauna have had long-lasting effects on forest structure (Malhi et al 2016; Doughty, Faurby, and Svenning 2016), plant geographic ranges (Doughty et al 2016; Janzen and Martin 1982; Blake et al 2009; Beaune et al 2013), carbon storage (Doughty et al 2016), maintenance of high latitude grasslands (Murchie et al 2021; Zimov et al 2015; Bakker et al 2016), nutrient cycling (Doughty 2017; Wolf, Doughty, and Malhi 2013; Doughty et al 2016; Doughty, Wolf, and Malhi 2013), the perceived host specificity of parasites (Farrell et al 2021) and emergent zoonotic diseases (Doughty et al 2020). Additionally, the life-history traits of the megafauna are not yet classified, limiting our understanding of these big species and the accuracy of studies modelling their impact.…”