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Ancient ‘cheetah’ adapted to a fish-based diet to survive

When the now-extinct American cheetah was enduring the last ice age, a glaciated barrier broke up its territory into two distinct territories — one in central North America and another much farther north.

Analysis from the Alaska Stable Isotope Facility at the 51�������� helped an international research team uncover how the ancient carnivore survived in those distinct regions. American cheetahs in the southern range hunted terrestrial prey like pronghorn antelope. Their counterparts in the Arctic adapted to their environment by making fish a staple of their diets.

Matthew Wooller, the director of the Alaska Stable Isotope Facility, said he was “mind-blown” when those differences came into focus.

“This species of carnivore has this massive range, all the way from the Arctic to the Lower 48,” said Wooller, who is also a professor at 51��������’s College of Fisheries and Ocean Sciences. “They’re demonstrating über-specialization at two ends of their range, while also feeding on two completely different food sources.”

The dietary discovery was part of a broader look into the history of the ancient cat, led by Molly Cassatt-Johnstone from the University of California, Santa Cruz. The study found that the separate populations of American cheetah (Miracinonyx trumani) were a single species more closely related to pumas than modern-day cheetahs.

The findings .

The research team analyzed samples from cheetahs that lived in Wyoming and the Yukon about 23,000 and 31,000 years ago, respectively. The team tested stable nitrogen isotopes in amino acids, a sophisticated technique for determining the cheetahs’ primary food sources.

It revealed that cheetahs living in the far North were aquatic specialists, subsisting largely on an undetermined anadromous fish species. Their reliance on fish far outpaced even that of modern salmon-eating bears in Alaska, according to the analysis.

The American cheetahs living in modern-day Wyoming had a much more typical diet of a terrestrial carnivore, with their prey consisting mainly of herbivores.

“It was just so cool to see that these cats behaved like totally different predators depending on where they were,” Cassatt-Johnstone said. “With extinct animals, it’s so much easier to flatten them into a single caricature. This was a great reminder that we need to let extinct species be just as dynamic and variable as the modern ones we live with today.”

Learning about the adaptations made by ancient species during and after the last ice age can inform our understanding of how more rapid changes could unfold in the far North today, Wooller said.

“With the ongoing impact of current climate change in the Arctic, we’re seeing pressures being applied to modern megafaunal species like caribou and polar bears,” Wooller said. “By studying the past we have the opportunity to study ecological experiments that took place over tens of thousands of years.”

ADDITIONAL CONTACT: Matthew Wooller, mjwooller@alaska.edu

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