Ancient DNA found in soil samples reveals mammoths, Yukon wild horses
survived thousands of years longer than believed

Date:
December 8, 2021
Source:
McMaster University
Summary:
Mere spoonsful of soil pulled from Canada's permafrost are opening
vast windows into ancient life in the Yukon, revealing rich new
information and rewriting previous beliefs about the extinction
dynamics, dates and survival of megafauna like mammoths, horses
and other long-lost life forms.



FULL STORY ==========================================================================
Mere spoonfuls of soil pulled from Canada's permafrost are opening vast
windows into ancient life in the Yukon, revealing rich new information
and rewriting previous beliefs about the extinction dynamics, dates
and survival of megafauna like mammoths, horses and other long-lost
life forms.


==========================================================================
In a new paper, published in the journal Nature Communications,
researchers from McMaster University, the University of Alberta, the
American Museum of Natural History and the Yukon government present a 30,000-year DNA record of past environments, drawn from cored permafrost sediments extracted from the Klondike region of central Yukon.

Researchers used DNA capture-enrichment technology developed at McMaster
to isolate and rebuild, in remarkable detail, the fluctuating animal and
plant communities at different time points during the Pleistocene-Holocene transition, an unstable climatic period 11,000-14,000 years ago when a
number of large species such as mammoths, mastodons and sabre-toothed
cats disappeared.

They reconstructed the ancient ecosystems using tiny soil samples which
contain billions of microscopic genomic sequences from animal and plant species.

The analysis reveals that mammoths and horses were already in steep
decline prior to the climatic instability, but they did not immediately disappear due to human overhunting as previously thought. In fact, the
DNA evidence shows that both the woolly mammoth and North American horse persisted until as recently as 5,000 years ago, bringing them into the mid-Holocene, the interval beginning roughly 11,000 years ago that we
live in today.

Through the early Holocene the Yukon environment continued to experience massive change. Formerly rich grasslands -- the "Mammoth Steppe" --
were overrun with shrubs and mosses, species no longer held in check
by large grazing herds of mammoths, horses and bison. Today, grasslands
do not prosper in northern North America, in part because there are no megafaunal "ecological engineers" to manage them.

"The rich data provides a unique window into the population dynamics of megafuana and nuances the discussion around their extinction through more subtle reconstructions of past ecosystems" says evolutionary geneticist
Hendrik Poinar, a lead author on the paper and director of the McMaster
Ancient DNA Centre.

This work builds on previous research by McMaster scientists who had
determined woolly mammoths and the North American horse were likely
present in the Yukon approximately 9,700 years ago. Better techniques
and further investigation have since refined the earlier analysis and
pushed forward the date even closer to contemporary time.

"Now that we have these technologies, we realize how much life-history information is stored in permafrost,"explains Tyler Murchie, a
postdoctoral researcher in McMaster's Department of Anthropology and a
lead author of the study.

"The amount of genetic data in permafrost is quite enormous and really
allows for a scale of ecosystem and evolutionary reconstruction that is unparalleled with other methods to date" he says.

"Although mammoths are gone forever, horses are not" says Ross MacPhee
of the American Museum of Natural History, another co-author. "The horse
that lived in the Yukon 5,000 years ago is directly related to the horse species we have today, Equus caballus. Biologically, this makes the
horse a native North American mammal, and it should be treated as such." Scientists also stress the need to gather and archive more permafrost
samples, which are at risk of being lost forever as the Arctic warms.

========================================================================== Story Source: Materials provided by McMaster_University. Original written
by Michelle Donovan. Note: Content may be edited for style and length.


========================================================================== Related Multimedia:
* Ancient_sediment_DNA ========================================================================== Journal Reference:
1. Tyler J. Murchie, Alistair J. Monteath, Matthew E. Mahony, George S.

Long, Scott Cocker, Tara Sadoway, Emil Karpinski, Grant Zazula,
Ross D.

E. MacPhee, Duane Froese, Hendrik N. Poinar. Collapse of
the mammoth- steppe in central Yukon as revealed by ancient
environmental DNA. Nature Communications, 2021; 12 (1) DOI:
10.1038/s41467-021-27439-6 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211208090008.htm

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