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Mastodons migrated vast distances in response to climate change

New research suggests North American mastodons traveled great distances, moving northward as glaciers receded during the Pleistocene. Photo by D. Finnin/American Museum of Natural History
New research suggests North American mastodons traveled great distances, moving northward as glaciers receded during the Pleistocene. Photo by D. Finnin/American Museum of Natural History

Sept. 1 (UPI) -- Before their disappearance at the end of the Pleistocene, North American mastodons trekked hundreds of miles across the continent, altering their range in response to dramatic climatic shifts, according to research published Tuesday in Nature Communications.

In a largest-of-its-kind survey of mastodon mitochondrial genomes, using DNA collected from 33 individual animals, researchers were able to retrace the movements of ancient mastodon populations.

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"We used one genetic marker known as the full mitochondrial genome," Hendrik Poinar, evolutionary geneticist and director of the Ancient DNA Center at McMaster University in Canada, told UPI in an email. "This is a maternally inherited marker that does not recombine and allows us to trace migration history and female population size through time."

"We compared the mitochondrial genomes from all mastodons to say something about where they fall in relation to each other," Poinar said. "When combined with their geographical location you can make sense of migrational direction."

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The genomic data showed mastodons from farther north featured lower levels of genetic diversity, suggesting smaller subsets of southern populations migrated north.

By comparing differences in the number of genetic mutations between individual mastodons and geographically distinct groups of mastodons, researchers were able to better understand the relationships between different population subsets. They also were able to estimate when different branches of the family tree split off and migrated elsewhere.

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When researchers compared the timing of mastodon migrations with paleoclimate evidence, they were able to confirm that groups of mastodons headed north as temperature rose and glaciers receded.

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"The interglacial occupation of mastodons has been proposed for a few years now, but I think we show the strongest evidence of it," lead study author Emil Karpinski, graduate student at the Ancient DNA Center, told UPI.

Scientists have previously suggested North American mastodons were hunted to extinction by people of the Clovis culture, a prehistoric Paleoamerican culture that spread across the continent some 13,000 years ago. But the latest research suggests climate change likely played a role in the mastodon's disappearance.

"[The findings] certainly suggest that the mastodons migrated huge distances over the course of generations, tracking environments that favored their ecology, but ultimately that they were susceptible to changing climate, perhaps priming them for human predation," Poinar said.

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The researchers say their findings have implications for modern conservation science. Today, a variety of animal species, including elk and bears, are expanding their ranges northward as a result of anthropogenic greening.

"If these northern populations show the same pattern as mastodons, they might also be very similar genetically and the loss of populations in the southern ranges may have detrimental effects for the genetic health of the species," Karpinski said.

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