Relict permafrost preserves megafauna, insects, pollen, soils and pore-ice isotopes of the mammoth steppe and its collapse in central Yukon

Permafrost microbial communities follow shifts in vegetation, soils, and megafauna extinctions in Late Pleistocene NW North America

“…Correlation plots (Figure 5; Figure S5) with hierarchical clustering of significantly differing prokaryotic and eukaryotic genera also recapitulate that communities of bacteria, archaea, fungi, plants, and animals cluster into two major groups—mammoth steppe and woody shrubland ecosystems—as we would expect based on previous research of the Late Pleistocene/Holocene transition in eastern Beringia (Guthrie, 2001; Monteath et al., 2021, 2023; Murchie, Monteath, et al., 2021; Wang, Pedersen, et al., 2021; Willerslev et al., 2014). Late Glacial megafauna (woolly mammoth, horse, bison, dall sheep, and caribou) correlate positively in these analyses with several bacteria (including Clavibacter , Amycolatopsis , Micromonospora , Clostridium , Nitrospira , Anaeromyxobacter , Oscillatoria , Sporosarcina , and Pseudoncardia), archaea ( Methanobrevibacter ), and plants ( Meconopsis and Papaver [poppies], Taraxacum [dandelions], Saxifraga [rockfoils], and Poaceae [grasses]), along with other herbaceous and graminoid species and fungi ( Glarea , Endocarpon , Rhizophagus , Pleosporineae).…”

“…(2021) and Monteath et al. (2023) observed a significant and rapid shift in multiple paleo‐ecological proxies at the Lucky Lady site between 13,480 and 13,210 cal BP, corresponding here with samples PHP‐5 (13,510 cal BP), PHP‐6 (13,335 cal BP), and PHP‐4 (13,176 cal BP). This period initially is associated with the development of a prominent paleosol, including the decline of steppe‐tundra indicators like Artemisia spp.…”

“…This period initially is associated with the development of a prominent paleosol, including the decline of steppe‐tundra indicators like Artemisia spp. (sage, as indicated by both pollen and eDNA) and steppe weevil ( Connatichela artemisiae ), and their replacement by 13,210 cal BP with sedges (Cyperaceae), ground‐nesting birds such as willow ptarmigan ( Lagopus lagopus ), and woody shrubs like Salix , Alnus , Betula , Populus and Ericaceae (Monteath et al., 2023; Murchie, Monteath, et al., 2021). It is during this transition in sample PHP‐6 that we see an increase in the signals from the genera Rhodoferax , Acidovorax , and Polaromonas , with Rhodoferax being commonly associated with stagnant, waterlogged environments exposed to light (Hiraishi et al., 1991; Jin et al., 2020).…”

“…The macro‐ecosystems of each sample (mammoth steppe, woody shrublands, and boreal forest) were used as proxies for both the age and climatic conditions. This is especially relevant as the mammoth steppe was more arid and cool than the Holocene‐aged core samples from latter woody shrubland and boreal forest periods (Mann et al., 2013; Monteath et al., 2023; Zimov et al., 2012). A mixed linear model was used to control for the preservation effects conferred by the sampling location as well as the mapped bacteria in relation to both the deamination and depurination rates.…”

“…The Pleistocene–Holocene transition (ca. 11,700 years ago) resulted in continental‐scale biogeographic range shifts in ecological communities of plants and animals (Bakker, Gill, et al., 2016; Bakker, Pagès, et al., 2016; Brault et al., 2013; Doughty et al., 2013, 2015, 2016; Guthrie, 1990, 1995, 2006; Malhi et al., 2016; Monteath et al., 2021, 2023; Murchie, Monteath, et al., 2021; Smith et al., 2015; Wang, Pedersen, et al., 2021; Willerslev et al., 2014). From at least the Last Glacial Maximum (LGM, 26,500–19,000 years before present [BP]) (Clark, 2009) until the end of the Late Pleistocene, the northern hemisphere was populated by cold‐ and dry‐adapted flora and fauna as part of what is generally referred to as the mammoth steppe biome (Froese et al., 2009; Graf, 2008; Guthrie, 2001; Hoffecker et al., 2014; Hopkins et al., 1982; Kuzmina et al., 2011; Zazula et al., 2003; Zimov et al., 2012).…”