MISSOULA – White-tailed jackrabbits can change their color with the seasons, growing snowy white fur in the winter and brown fur during the summer. But shorter winters brought on by rapid climate change can create color mismatch, making jackrabbits stand out like lightbulbs for predators on snowless landscapes.

Populations of jackrabbits can display brown, white, or intermediate-colored coats during the winter, depending on how snowy their environment is. Now an international team led by University of Montana scientists has discovered three genes that determine jackrabbit color variation from white to brown. The genes control the production of pigments – the same pigments that determine if hair is darker or lighter in people. Understanding how the color variation evolved allowed the researchers to predict that certain jackrabbit populations will be better able to adapt to future declines of snow cover.

Winter landscapes provide formidable challenges for many animals.

“A dark animal will be more easily noticed by predators on a white snowy landscape. For prey like hares and jackrabbits, the ability to remain camouflaged can be the difference between life and death,” said Mafalda Ferreira, a Portuguese scientist who led the study while a graduate student working at UM.

Jeffrey Good, a UM professor of ecology and evolution who coordinated the study, said they applied the same cutting-edge technologies used to study human diseases to decode the genomes of jackrabbits with brown, white, or intermediate-colored winter coats. They then combined genetic results with climate projections to reveal that populations with higher variability in their color genes are better prepared to face the likely reductions in snow cover that will occur during the next century.

Scott Mills, a UM wildlife biology professor who was involved in the study, said this critical variation may help rescue white-tailed jackrabbits from population declines caused by climate change.

Nevertheless, the authors offer a cautionary note to this optimistic prediction. A final and striking result is that this adaptive capacity was found most often in populations threatened by habitat loss, diseases, and targeted extermination by humans. For the team, this highlights how maintaining connectivity between populations will be essential to ensure the conservation of this species and others in the long run.

“Although this might be good news for jackrabbits, our discoveries also serve as a cautionary tale for other animals facing the impact of climate change,” Good said. “When people think about wildlife conservation, what normally comes to mind is the protection of populations and habitats. The jackrabbits and their coat colors show how the genetic diversity of a species is just as important, particularly in this rapidly changing natural world.”

The team’s work was published March 23 in Science Magazine in an article titled “The evolution of white-tailed jackrabbit camouflage in response to past and future seasonal climates.” The article is online HERE.

- by UM News Service -

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