97 New Perspectives on Beringian Paleoecology, Paleoclimate, and Paleoceanography

This session will showcase the use of new sedimentary records and analytical techniques to augment reconstructions of Beringian and North Pacific Gateway paleoclimate and paleoecology and elucidate the role of terrestrial and marine linkages.

Monday, 20 October 2025
8:00 AM - 12:00 PM
HBGCC, 303C

Sedimentary Ancient DNA Indicates Continuity of Beringian Megafauna Phylogenetic Genetic Diversity Following Deposition of the Late Pleistocene Dawson Tephra 29,000 Years Ago

Paper number: 97-12
Program: Technical Sessions
Time: 11:00 AM – 11:20 AM

Authors

Abstract

Volcanic eruptions can deposit ash, also known as tephra, across the landscape hundreds to thousands of kilometers from the source volcano. Although the ecological effects of ancient ashfall events are only known from the geological record, DNA analyses have shown that past volcanic events contributed to modern population structure and genetic diversity of some species. Here, we explore the effects of an ancient ashfall on the genetic diversity of four megafauna species. Around 29,000 years ago, a volcanic eruption in the Aleutian archipelago with an estimated eruption volume of >50 km3 and volcanic explosivity index (VEI) of 6 deposited ash across the eastern Beringian steppe. The resulting Dawson tephra is visible in loess deposits in interior Alaska and Yukon, with thicknesses ranging from 5 to 80 cm at a distance of 1700 km from its source. We used sedimentary ancient DNA (sedaDNA) approaches to isolate genomic data from several exposures of Dawson tephra in the Klondike region of Yukon, Canada, and examine differences in population-level mitochondrial diversity in the region before and after the ashfall. We found no significant change in horse, bison, mammoth, or caribou genetic diversity after the ashfall. Our results suggest that the effects of the ashfall on these populations were minimal and did not cause population turnover or bottlenecks. This study reinforces the value of sedaDNA to investigate past environmental dynamics.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412409

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