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Tracking late-quaternary extinctions in interior Alaska using megaherbivore bone remains and dung fungal spores

Tracking late-quaternary extinctions in interior Alaska using megaherbivore bone remains and dung fungal spores
Tracking late-quaternary extinctions in interior Alaska using megaherbivore bone remains and dung fungal spores

One major challenge in the study of late-Quaternary extinctions (LQEs) is providing better estimates of past megafauna abundance. To show how megaherbivore population size varied before and after the last extinctions in interior Alaska, we use both a database of radiocarbon-dated bone remains (spanning 25-0 ka) and spores of the obligate dung fungus, Sporormiella, recovered from radiocarbon-dated lake-sediment cores (spanning 17-0 ka). Bone fossils show that the last stage of LQEs in the region occurred at about 13 ka ago, but the number of megaherbivore bones remains high into the Holocene. Sporormiella abundance also remains high into the Holocene and does not decrease with major vegetation changes recorded by arboreal pollen percentages. At two sites, the interpretation of Sporormiella was enhanced by additional dung fungal spore types (e.g., Sordaria). In contrast to many sites where the last stage of LQEs is marked by a sharp decline in Sporormiella abundance, in interior Alaska our results indicate the continuance of megaherbivore abundance, albeit with a major taxonomic turnover (including Mammuthus and Equus extinction) from predominantly grazing to browsing dietary guilds. This new and robust evidence implies that regional LQEs were not systematically associated with crashes of overall megaherbivore abundance.

Beringia, Coprophilous fungal spores, Fossil, Herbivore, Last glacial maximum, Megafauna, Paleoecology, Sordaria, Sporormiella, Transition
0033-5894
99-110
Conroy, Keziah J.
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Baker, Ambroise G.
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Jones, Vivienne J.
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Van Hardenbroek, Maarten
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Hopla, Emma J.
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Collier, Robert
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Lister, Adrian M.
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Edwards, Mary E.
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Conroy, Keziah J.
26fe526f-8690-4983-834f-f5dae9b1fa8d
Baker, Ambroise G.
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Jones, Vivienne J.
f416e53b-b5bf-407f-887c-fe2db8f3dd53
Van Hardenbroek, Maarten
b68dde18-5726-4964-b01e-72417b5f149f
Hopla, Emma J.
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Collier, Robert
3c208280-ac53-4f8b-9c62-3278e63bffb4
Lister, Adrian M.
31dcc974-f8aa-47f9-94e5-e30c3d0ee187
Edwards, Mary E.
4b6a3389-f3a4-4933-b8fd-acdfef72200e

Conroy, Keziah J., Baker, Ambroise G., Jones, Vivienne J., Van Hardenbroek, Maarten, Hopla, Emma J., Collier, Robert, Lister, Adrian M. and Edwards, Mary E. (2020) Tracking late-quaternary extinctions in interior Alaska using megaherbivore bone remains and dung fungal spores. Quaternary Research (United States), 97, 99-110. (doi:10.1017/qua.2020.19).

Record type: Article

Abstract

One major challenge in the study of late-Quaternary extinctions (LQEs) is providing better estimates of past megafauna abundance. To show how megaherbivore population size varied before and after the last extinctions in interior Alaska, we use both a database of radiocarbon-dated bone remains (spanning 25-0 ka) and spores of the obligate dung fungus, Sporormiella, recovered from radiocarbon-dated lake-sediment cores (spanning 17-0 ka). Bone fossils show that the last stage of LQEs in the region occurred at about 13 ka ago, but the number of megaherbivore bones remains high into the Holocene. Sporormiella abundance also remains high into the Holocene and does not decrease with major vegetation changes recorded by arboreal pollen percentages. At two sites, the interpretation of Sporormiella was enhanced by additional dung fungal spore types (e.g., Sordaria). In contrast to many sites where the last stage of LQEs is marked by a sharp decline in Sporormiella abundance, in interior Alaska our results indicate the continuance of megaherbivore abundance, albeit with a major taxonomic turnover (including Mammuthus and Equus extinction) from predominantly grazing to browsing dietary guilds. This new and robust evidence implies that regional LQEs were not systematically associated with crashes of overall megaherbivore abundance.

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6205DF07-4EE6-4727-83B8-1370E66A7618 - Accepted Manuscript
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Published date: 1 September 2020
Additional Information: Funding Information: This work was funded by NERC; Lakes and the arctic carbon cycle NE/K000306/1. Radiocarbon dating was supported by the NERC Radiocarbon Facility NRCF010001 (allocation numbers 1726.0813 and 1847.1014), and we kindly acknowledge the efforts of Dr. Charlotte Bryant. Tony Stuart kindly shared some dates from the Lister/Stuart megafaunal extinctions project (NERC grants GR3/12599 and NE/D003105/1). We thank Dr. Xiaomei Xu at the Keck Carbon Cycle AMS Facility, University of California, Irvine, USA, for her expertise in low current AMS. We also thank Hannah Laurens, Tom Roland, and Kim Davies for their invaluable help in the field, and Nancy Bigelow and the Alaska Quaternary Center for the loan of equipment. The manuscript was greatly improved by the comments of two anonymous referees, Associate Editor Jeff Pigati, and Senior Editor Derek Booth. Funding Information: This work was funded by NERC; Lakes and the arctic carbon cycle NE/K000306/1. Radiocarbon dating was supported by the NERC Radiocarbon Facility NRCF010001 (allocation numbers 1726.0813 and 1847.1014), and we kindly acknowledge the efforts of Dr. Charlotte Bryant. Tony Stuart kindly shared some dates from the Lister/Stuart megafaunal extinctions project (NERC grants GR3/ 12599 and NE/D003105/1). We thank Dr. Xiaomei Xu at the Keck Carbon Cycle AMS Facility, University of California, Irvine, USA, for her expertise in low current AMS. We also thank Hannah Laurens, Tom Roland, and Kim Davies for their invaluable help in the field, and Nancy Bigelow and the Alaska Quaternary Center for the loan of equipment. The manuscript was greatly improved by the comments of two anonymous referees, Associate Editor Jeff Pigati, and Senior Editor Derek Booth. Publisher Copyright: Copyright © 2020 University of Washington. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.
Keywords: Beringia, Coprophilous fungal spores, Fossil, Herbivore, Last glacial maximum, Megafauna, Paleoecology, Sordaria, Sporormiella, Transition

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Local EPrints ID: 453734
URI: http://eprints.soton.ac.uk/id/eprint/453734
ISSN: 0033-5894
PURE UUID: 385cf7a5-33b2-4ad1-a157-751568a03623
ORCID for Mary E. Edwards: ORCID iD orcid.org/0000-0002-3490-6682

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Date deposited: 21 Jan 2022 17:42
Last modified: 13 Aug 2022 01:39

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Contributors

Author: Keziah J. Conroy
Author: Ambroise G. Baker
Author: Vivienne J. Jones
Author: Maarten Van Hardenbroek
Author: Emma J. Hopla
Author: Robert Collier
Author: Adrian M. Lister
Author: Mary E. Edwards ORCID iD

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