Rapid range shifts and megafaunal extinctions associated with late Pleistocene climate change

Frederik V Seersholm,Gregory Mcdonald,Taryn Johnson,Michael R Waters,Anna Linderholm,Ernest L Lundelius,Barbara Winsborough,Anders J Hansen,Beth Shapiro,Alicia Grealy,Erin M Keenan Early,Rickard Toomey,Thomas W Stafford,Michael Bunce,Grayal Earle Farr,Daniel J Werndly

doi:10.1038/s41467-020-16502-3

Abstract

Large-scale changes in global climate at the end of the Pleistocene significantly impacted ecosystems across North America. However, the pace and scale of biotic turnover in response to both the Younger Dryas cold period and subsequent Holocene rapid warming have been challenging to assess because of the scarcity of well dated fossil and pollen records that covers this period. Here we present an ancient DNA record from Hall’s Cave, Texas, that documents 100 vertebrate and 45 plant taxa from bulk fossils and sediment. We show that local plant and animal diversity dropped markedly during Younger Dryas cooling, but while plant diversity recovered in the early Holocene, animal diversity did not. Instead, five extant and nine extinct large bodied animals disappeared from the region at the end of the Pleistocene. Our findings suggest that climate change affected the local ecosystem in Texas over the Pleistocene-Holocene boundary, but climate change on its own may not explain the disappearance of the megafauna at the end of the Pleistocene.

Highlights

Large-scale changes in global climate at the end of the Pleistocene significantly impacted ecosystems across North America
We excavated 32 sediment samples to characterise the floral assemblage across the Pleistocene–Holocene boundary (Fig. 1, Supplementary Table 4), from which we amplified two short chloroplast loci: the P6 loop of trnL26 and a fragment of rbcL27(Supplementary Table 2)
By comparing bulk-bone metabarcoding with sedimentary ancient DNA (sedaDNA) excavated from Hall’s Cave, we find multiple lines of evidence supporting dramatic ecological change in central Texas between the LGM and Holocene

Summary

Introduction

Large-scale changes in global climate at the end of the Pleistocene significantly impacted ecosystems across North America. While people were widespread across the Americas by at least 13,000 cal BP3,5,6, their population sizes were small, and it remains unresolved how strongly hunting affected megafauna populations[3,7]. This has led to the widely accepted “one–two punch” hypothesis[8], whereby the combined effects of climate change and human impacts led to the extinction of the North American megafauna by approximately 13.0–12.5 ka cal BP9,10

Methods

Results

Conclusion