THIS RESEARCH WILL HAVE YOU HOWLING
Zoe Landry describes her work as a dream. As a researcher, her passion for paleontology and animals combine, allowing her to contribute to conservation efforts in a fulfilling way.
Her research at the University of Ottawa is mostly focused on the Pleistocene megafauna, meaning large-bodied mammals over the past 50,000 years. She’s interested in answering questions about species extinction and how it can be applied as a model for ongoing climate change.
This week, Landry spoke with the Fulcrum to discuss her and Danielle Frasers’ research on dietary shifting in Pleistocene and recent grey wolves.
How do the past and previous environments for grey wolves differ?
According to Landry, the Pleistocene is a geological epoch that lasted from 2,580,000 to 11,700 years ago. Her specimens were dated, on average, 30,000 years old. The environment in which they lived was vastly different from the environment of today, referred to as the Yukon.
“So, during the Pleistocene, the Yukon was much colder and much drier. Not a lot of precipitation, and we call it a mammoth step, which is basically a step tundra. So very wide open grassland, some shrubs here and there, no trees, but with mammoths present, you need mammoths to have a mammoth step,” said Landry.
On the other hand, “nowadays, the Yukon is, of course, still cold, [but] is generally warmer and a little bit wetter. So they get a lot more precipitation in the form of snow. They have those annual winter summer cycles, and there are a lot more trees. So it’s a lot more of a boreal forest environment right now. So much closer, and not as open as it was during the Pleistocene,” added Landry.
What is dental microwear and stable isotope analysis and how does it work?
Microdental wear, according to Landry, can be described as the microscopic patterns left on animals’ teeth as they ate. For wolves, she was specifically looking for pits and scratches which can indicate the relative hardness of each food item, in addition to the wolves’ feeding behaviour.
More pits would show wolves were eating harder foods and possibly mimic the crunching behaviour seen more commonly in hyenas. Linear scratches are more likely formed from teeth sliding over the top of one another, in a type of chewing often known as “meat slicing,” which is associated with softer foods and tissue. For wolves, this technique is useful to determine whether they were eating harder or softer foods.
In terms of stable isotope dating, Landry explained, “basically with stable isotopes, the axiom is you are what you eat. So all animals and plants have a certain isotope signature, that’s based on the food that we consume or the soil in which a plant lives.”
Additionally, “carbon isotopes are really useful because they kind of tell you, if an animal was more feeding on like C3 plants or more C4 plants. So think like grasses versus corn. Nitrogen is really useful because it tells you where an animal sits in the food chain, so you can see if it’s a top carnivore or if it’s more of a herbivore.”
Stable isotope dating has an advantage over dental microwear because of its ability to pinpoint more specifically what the wolves were eating based on the isotope signature, meaning that researchers could identify a horse’s isotope signature versus a sheep or ox’s signature.
What were the results?
Based on Landry’s research she found that “they were eating the same types of material in the Pleistocene as they do now or recently (1960). So a lot of the scratches (those linear features) would show us that they were mostly consuming fleshy organs, all of those softer tissues.”
She continued, “there was, you know, some pitting because they can’t perfectly pull the flesh just off the animal, they’re gonna have some bone in there. But that showed us that they were probably able to be active hunters and catch and defend their own prey even from all these other carnivores.”
This finding disrupts any preconceived notions that Pleistocene wolves were located at the bottom of the carnivore levels. Their feeding behaviours were once thought to mainly consist of scavenging, when in reality, they were most likely actively competing against other carnivores for food resources.
Most interestingly, “the isotopes basically showed us that in the past, Yukon wolves were really feeding mostly on horses, more than 50 per cent. They probably ate some caribou, some Dall, sheep, probably scavenged mammoths. However, horses went extinct in North America during the Pleistocene extinction.”
What stood out to researchers was that wolves were able to switch their diets from primarily horses in the Pleistocene to what we observe today — larger hoofed mammals (caribou, moose). This flexibility is what Landry predicts may have aided grey wolves to survive the Pleistocene extinction event.
Why didn’t larger carnivores of the Pleistocene survive?
Some other large carnivores that dominated the landscape during the Pleistocene were the short-faced bear, which is the largest terrestrial carnivore to ever exist, the American lion, and the scimitar cat.
When asked why they didn’t survive the Pleistocene extinction, Landry responded, “there are some ideas, but it’s thought that potentially they were really reliant on very large animals. So they were possibly mammoth specialists that had been proposed. But again, more research is definitely needed to determine that.”
She added, “it’s also thought that these carnivores might have been a little less flexible than wolves and wolves actually almost have an advantage over them because they were the smallest. Meaning that their energetic needs are lesser even though they operate in pack systems.”
Other than Landry’s research, which suggests wolves were more flexible in their diets, allowing them to switch from horses to hoofed mammals, she stressed the importance of more research to answer this question in more detail.
What’s next for Landry?
Currently, Landry is in the process of publishing her master’s research on polar bear diets. This research may be able to shed some light on how future polar bears will be able to manage climate change. However, she’s mainly working on her PhD, studying the phylogeny, extinction chronology, and ecology of Beringian horses.