Gray wolves are among the largest predators to have survived extinction at the end of the last ice age around 11,700 years ago. Today, they can be found roaming the boreal forest and the Yukon tundra, with caribou and elk as their main food sources.
A new study led by the Canadian Museum of Nature shows that wolves may have survived by adapting their diet for thousands of years. – from a primary dependence on horses during the Pleistocene, to caribou and elk today. The results are published in the journal Paleogeography, Paleoclimatology, Paleoecology.
The research team, led by museum paleontologist Dr. Danielle Fraser and student Zoe Landry, analyzed evidence preserved in ancient (50,000 to 26,000 years ago) and modern gray wolf skull bones and teeth. All specimens were collected in Yukon, a region that once supported Beringia’s mammoth and 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 on the wolf’s bones,” says Landry, the lead author who completed the work as a student at Carleton University under Fraser’s supervision. “These can tell us a lot about how the animal ate and what it was eating throughout its life, up to a few weeks before dying.”
Landry and Fraser relied on established models that can determine an animal’s feeding behavior by examining microscopic patterns of wear on its teeth. The scratch marks indicate that the wolf would have been consuming meat, while the presence of pits would suggest chewing and gnawing on bones, probably as a scavenger.
The analysis showed that scratch marks were prevalent on both ancient and modern wolf teeth, meaning that wolves continued to survive as primary predators, hunting their prey.
So what were the gray wolves eating? The modern diet (caribou and elk) is well established. The diet of ancient wolves was evaluated by observing the ratios of carbon and nitrogen isotopes extracted from collagen in the bones. Relative isotope levels can be compared to indicators established for specific species. “Here the axiom comes into play, you are what you eat,” says Landry.
The results showed that horses, which became extinct during the Pleistocene, accounted for about half of the gray wolf’s diet. About 15% came from caribou and Dall sheep, with some mammoths mixed in. All this at a time when ancient wolves would have coexisted with other large predators such as scimitar cats and short-faced bears. The eventual extinction of these predators could have created more opportunities for wolves to transition to new species of prey.
“This is really a story of survival and adaptation to the ice age, and the construction of a species towards the modern form in terms of ecological adaptation,” says Dr. Grant Zazula, co-author of the study and paleontologist from the Government of Yukon, who is an expert on the ice age animals that populated Beringia.
The findings have implications for conservation today. “Gray wolves showed flexibility to adapt to a changing climate and a change in habitat from a steppe ecosystem to a boreal forest,” explains Fraser. “And their survival is closely related to the survival of the prey species that they can eat.”
Given modern gray wolves’ reliance on caribou, the study authors suggest that preservation of caribou populations will be an important factor in maintaining a healthy wolf population.
Reference: “Dietary reconstruction and evidence of prey movement in the Pleistocene and recent gray wolves (Canis lupus) from the Yukon Territory ”by Zoe Landry, Sora Kim, Robin B. Trayler, Marisa Gilbert, Grant Zazula, John Southon, and Danielle Fraser, March 20, 2021, Paleogeography, Paleoclimatology, Paleoecology.
DOI: 10.1016 / j.palaeo.2021.110368
This study was supported by an NSERC Discovery Grant awarded to Dr. Danielle Fraser. Isotope analysis was performed by Dr. Sora Kim and Dr. Robin Trayler at the University of California, Merced. In total, the research team acquired data from 31 Pleistocene skulls, as well as data from 17 modern skulls (most collected in the 1960s). All specimens are in the collections of the Canadian Museum of Nature and the Yukon Government.