Evaluating Adaptations of Desert Bighorn Sheep to Climate Change in the Southwestern U.S.

In the southwestern U.S., climate change is expected to increase the frequency of extreme droughts and cause an overall decrease in precipitation and increase in temperatures. These changes could impact a wide range of species in the region, even those adapted to living in arid environments. It’s possible that some species may be able to adapt to changing conditions by migrating to new locations or altering their behavior, while others may have genetic traits that activate physiological changes to cope with heat and water stress.
 
This project focused on desert bighorn sheep and explored potential adaptations that may help them persist despite varying climates throughout their range. Previous research has shown that some sheep populations may already be declining due to the impacts of reduced rainfall on water availability and vegetation quality and quantity. This project sought to determine whether some populations carry genetic traits that enable them to tolerate hotter and drier conditions. Researchers compared DNA samples from desert bighorn sheep in three different desert ecosystems in the Southwest. Each of these ecosystems has a slightly different local climate, and it’s possible that bighorn sheep in the hotter and drier ecosystems have evolved mechanisms to better cope with the particularly harsh conditions.

This comparison was designed to inform our understanding of whether desert bighorn sheep may be vulnerable, given projected changes in temperature and precipitation. Further, the results can help wildlife managers determine which actions may allow for desert bighorn sheep to persist as the climate continues to change.