Scott Mills, an N.C. State alumnus, has returned from the University of Montana to conduct research at N.C. State about the effects of climate change on hare populations.
Mills said 11 different species of known animals change from brown to white during the fall and winter and back to brown during the spring. According to Mills, these animals do this to match their environment and avoid becoming prey.
“The trigger for them to do that is based on day length. Over time that’s a really good signal for the hares to match snow being there,” Mills said. “Typically, when the days get shorter in the fall, snow comes and when days get longer is when snow goes away. That’s been a good signal for the seasonal changing animals to track the presence or absence of snow.”
Mills said there are a lot of variables that influence climate change in specific regions. Some areas are hotter while others are wetter, but the reduction of snow is a consistent factor.
“Seasonal places all over the world that get seasonal snow are getting fewer and fewer days of snow,” Mills said. “These hares encounter the shorter days in the fall and the longer days in the spring and they do their molt but find themselves mismatched against the background. They find themselves turning white and there is no snow.”
After two years of research, Mills said he believes that the reduction of snow is causing a mismatch. According to Mills, the mismatched hares die at a greater rate than those that blend with their environment. While mismatch is occurring, Mills said there has yet to be any noticeable decline in their populations.
“There is potential for evolution to change the timing of their molt, so [the hares] better track the presence and absence of snow,” Mills said. “While this mismatch is occurring, there is no noticeable decline in the hare population or in the populations of predators that rely on the hare.”
According to Mills, mismatch has been noted before but this is the first time coat color mismatch can be linked to climate change.
“We don’t really have any baseline to go back to and say ‘How does it compare now to 30 or 40 years ago?’ People were not thinking about climate change back then,” Mills said. “One of the interesting things about this trait is that in some places animals have evolved to just stay brown. This is evidence that nature has done a pretty good job shaping animals to their local environment.”
Mills said he is unsure whether or not the hares’ natural adaptations can keep up with the “superfast conditions of climate change.”
Mills began this research at the University of Montana and expects to continue this line of research at N.C. State.
“We have international connections to expand this work around the world,” Mills said. “We asked ‘Is mismatch happening,’ ‘Is mismatch more likely to increase in the future,’ and ‘Might there be a potential for animals to adapt to prevent mismatch?’”
Mills said he is interested in seeing how common the issue is around the world, and hopes to examine whether or not evolution can rescue the animals being mismatched. Mills said the research requires him to connect field data to an understanding of the genetic mechanism that causes animals to change color seasonally.
“We are studying that genetic mechanism with genetic tools also we are building a facility that will let us raise animals in very controlled conditions,” Mills said. “This will help us understand the evolution of the ability of animals to change to their conditions.”
