Seasonal Habitat Quality and Landscape Characteristics Explain Genetic Differences Between Greater Sage-grouse Populations in Wyoming

FORT COLLINS, Colo. — Low-quality nesting and winter seasonal habitats are strong predictors of reduced gene flow between greater sage-grouse breeding locations, according to research just published in Ecology and Evolution and authored by the U.S. Geological Survey and their colleagues at the University of Waterloo.  

The study compared the genetic differences between greater sage-grouse breeding areas with seasonal habitat distributions or combinations of landscape factors – such as amount of sagebrush habitat, agriculture fields or roads – to understand how each factor or combination of factors influence effective dispersal of sage-grouse across the state.

Understanding how habitat and landscape features impact the effective dispersal of a species is important for informing management and conservation decisions across large landscapes. Dispersal effectiveness can be measured by gene flow, the rate at which genetic material moves between populations. When populations become small and isolated, a reduction in gene flow can lead to reduced genetic diversity, making those populations potentially less resilient to environmental stressors.

“This research identified which seasonal habitats and individual landscape features facilitate and impede gene flow across the state of Wyoming – which is a stronghold for sage-grouse populations,” said Brad Fedy, one of the authors of the paper and a scientist at the University of Waterloo in Ontario.

Greater sage-grouse are dependent upon sagebrush, so two populations separated only by sagebrush habitat would be expected to have more individuals moving between them and be more genetically similar than two populations separated by a barrier to sage-grouse movement, such as a mountain range or forest.

Researchers found that the juxtaposition and quality of nesting and winter seasonal habitats were the greatest predictors of gene flow for greater sage-grouse in Wyoming. Furthermore, the combinations of high levels of forest cover and highly rugged (steep and uneven) terrain or low levels of sagebrush cover and highly rugged terrain were correlated with low levels of gene flow among sage-grouse populations.

“Maintaining natural levels of gene flow among populations helps ensure resilience for the species,” said Sara Oyler-McCance, a USGS research geneticist and a co-author on the study. “Ultimately, land managers can use this information to identify habitats that are most important for maintaining effective dispersal between populations and to improve future sage-grouse conservation efforts.”

Greater sage-grouse occur in parts of 11 U.S. states and 2 Canadian provinces in western North America.  These birds rely on sagebrush ecosystems, which constitute the largest single North American shrub ecosystem and provide vital ecological, hydrological, biological, agricultural, and recreational ecosystem services. The U.S. Fish and Wildlife Service is formally reviewing the status of greater sage-grouse to determine if the species is warranted for listing under the Endangered Species Act.