How grey wolves survived ice age extinction

Toronto: Grey wolves which are among the largest predators to have survived the extinction at the end of the last ice age around 11,700 years ago probably did so by adapting their diet over thousands of years, from a primary reliance on horses during the Pleistocene, to caribou and moose today, says a new study.

The study led by the Canadian Museum of Nature analysed evidence preserved in teeth and bones from the skulls of both ancient (50,000 to 26,000 years ago) and modern grey wolves. The research team, led by museum palaeontologist Danielle Fraser and student Zoe Landry, published their results in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

All the specimens were collected in Yukon, a region that once supported the Beringia mammoth-steppe ecosystem, and are curated in the museum's national collections as well as those of the Yukon government.

"We can study the change in diet by examining wear patterns on the teeth and chemical traces in the wolf bones," says Landry, the lead author who completed the work as a Carleton University student under Fraser's supervision. "These can tell us a lot about how the animal ate, and what the animal was eating throughout its life, up until about a few weeks before it died."

Landry and Fraser relied on established models that can determine an animal's eating behaviour by examining microscopic wear patterns on its teeth. Scratch marks indicate the wolf would have been consuming flesh, while the presence of pits would suggest chewing and gnawing on bones, likely as a scavenger.

Analysis showed that scratch marks prevailed in both the ancient and modern wolf teeth, meaning that the wolves continued to survive as primary predators, hunting their prey. What then were the grey wolves eating? The modern diet — caribou and moose — is well established.

The diet of the ancient wolves was assessed by looking at the ratios of carbon and nitrogen isotopes extracted from collagen in the bones. Relative levels of the isotopes can be compared with established indicators for specific species.

"The axiom, you are what you eat comes into play here," said Landry. "This is really a story of ice age survival and adaptation, and the building up of a species towards the modern form in terms of ecological adaptation," noted Grant Zazula, study co-author, and Government of Yukon paleontologist.

The findings have implications for conservation today. "The grey wolves showed flexibility in adapting to a changing climate and a shift in habitat from a steppe ecosystem to boreal forest," explained Fraser. "And their survival is closely linked to the survival of prey species that they are able to eat."

Given the reliance of modern grey wolves on caribou, the study's authors suggest that the preservation of caribou populations will be an important factor in maintaining a healthy wolf population.

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