Fifty thousand years of Arctic vegetation and megafaunal diet

Abstract

Although it is generally agreed that the Arctic flora is among the youngest and least diverse on Earth, the processes that shaped it are poorly understood. Here we present 50 thousand years (kyr) of Arctic vegetation history, derived from the first large-scale ancient DNA metabarcoding study of circumpolar plant diversity. For this interval we also explore nematode diversity as a proxy for modelling vegetation cover and soil quality, and diets of herbivorous megafaunal mammals, many of which became extinct around 10 kyr bp (before present). For much of the period investigated, Arctic vegetation consisted of dry steppe-tundra dominated by forbs (non-graminoid herbaceous vascular plants). During the Last Glacial Maximum (25-15 kyr bp), diversity declined markedly, although forbs remained dominant. Much changed after 10 kyr bp, with the appearance of moist tundra dominated by woody plants and graminoids. Our analyses indicate that both graminoids and forbs would have featured in megafaunal diets. As such, our findings question the predominance of a Late Quaternary graminoid-dominated Arctic mammoth steppe.

Combining paleo-data and modern exclosure experiments to assess the impact of megafauna extinctions on woody vegetation

“…The nine extinct Late Pleistocene proboscideans had divergent feeding strategies, from the predominantly grazing woolly mammoth (Mammuthus primigenius) to the browsing American mastodon (Mammut americanum) (57-59), the latter being supposedly most similar in feeding ecology to present-day browsing black rhinoceros (Diceros bicornis) or moose (A. americanus) (60,61). Whereas some niche separation was evident (57,61,62), recent multiproxy data on megaherbivore paleodiets suggests that many were mixed feeders that adapted their diets to local plant availability (62)(63)(64). Similarly, extant megaherbivores are mostly mixed feeders with a few grazing specialists like the hippopotamus (Hippopotamus amphibius) and white rhinoceros (Ceratotherium simum) (65).…”

Worldwide Analysis of Sedimentary DNA Reveals Major Gaps in Taxonomic Knowledge of Deep-Sea Benthos

“…These uncertainties should not undermine the potential of metabarcoding to better understand the diversity of poorly known communities. Indeed, the total information obtained from a large number of taxa in parallel provides a good estimator of environmental community diversity that has many practical applications for ecosystem assessment and monitoring (Chariton et al, 2010(Chariton et al, , 2014Czernik et al, 2013;Stephenson et al, 2013;Lallias et al, 2014;Pawlowski et al, 2014;Willerslev et al, 2014;Guardiola et al, 2015;Lejzerowicz et al, 2015;Pochon et al, 2015;Boschen et al, 2016).…”

High-throughput sequencing of African chikanda cake highlights conservation challenges in orchids

“…Most metabarcoding studies focusing on plants have used the plastid trnL P6 loop, as it has high primer universality, short amplicon length, high stability and high sequence variation. The combination of these characteristics has made trnL P6 the marker of choice for ancient DNA and ancient sediment DNA metabarcoding studies Parducci et al 2012;Taberlet et al 2012;Boessenkool et al 2014;Willerslev et al 2014). The use of nrITS1 and nrITS2 has been limited due to the shorter read length of previous highthroughput sequencing platforms, but the markers are more variable and have a greater potential for identification at finer taxonomic scales than the shorter and less variable trnL P6 loop.…”