A multidisciplinary study of a Late Pleistocene arctic ground squirrel (Urocitellus parryii) midden from Yukon, Canada

Abstract

Middens (nests and caches) of Late Pleistocene arctic ground squirrels (Urocitellus parryii) that are preserved in the permafrost of Beringia archive valuable paleoecological data. Arctic ground squirrels selectively include the plant material placed in middens. To account for this selectivity bias, we used a multi-proxy approach that includes ancient DNA (aDNA) and macro- and microfossil analyses. Here, we provide insight into Pleistocene vegetation conditions using macrofossils, pollen, phytoliths and non-pollen palynomorphs, and aDNA collected from one such midden from the Yukon Territory (Canada), which was formed between 30,740 and 30,380 cal yr BP. aDNA confirmed the midden was constructed by U. parryii. We recovered 39 vascular plant and bryophyte genera and 68 fungal genera from the midden samples. Grass and other herbaceous families dominated vegetation assemblages according to all proxies. aDNA data yielded several records of vascular plants that are outside their current biogeographic range, while some of the recovered fungi yielded additional evidence for local occurrence of Picea trees during glacial conditions. We propose that future work on fossil middens should combine the study of macro- and microfossils with aDNA analysis to get the most out of these environmental archives.

Predicting sample success for large‐scale ancient DNA studies on marine mammals

“…Previous studies have also revealed a certain degree of overlap between amplifiable DNA from Arctic and temperate conditions (Pruvost et al, 2007). Furthermore, the exceptional preservation conditions described for the most northerly latitudes (e.gCampos et al, 2010; Langeveld et al, 2017; Shapiro, 2004) may only be of benefit at much longer time‐scales of tens of thousands of years (e.g., Orlando et al, 2013; Schwarz et al, 2009). For comparatively younger samples as in this study, the slow rate of soil deposition and annual freezing‐thawing cycles may make them more vulnerable than initially expected (Kendall et al, 2017; Ping et al, 1998).…”

“…Previous studies have also revealed a certain degree of overlap between amplifiable DNA from Arctic and temperate conditions (Pruvost et al, 2007). Furthermore, the exceptional preservation conditions described for the most northerly latitudes (e.gCampos et al, 2010;Langeveld et al, 2017;Shapiro, 2004) may only be of benefit at much longer time-scales of tens of thousands of years (e.g., Orlando et al, 2013;Schwarz et al, 2009).…”

Modern botanical analogue of endangered Yak (Bos mutus) dung from India: Plausible linkage with extant and extinct megaherbivores

“…It is clear that pollen and spores incorporated into the stomach contents also reflect the composition of local vegetation and also reflects regional climate [16,17]. The study of the macrobotanical remains from a dung midden of an arctic ground squirrel and horse [17,18] provided information on both the animal’s diet and the local vegetation. The distribution of herbivorous animals within an ecosystem is often dependent on vegetation composition and its regional distribution [19–22].…”