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Sustaining the Greater sage-grouse may come down to maintaining genetic connectivity

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This figure depicts the overall ranking of node importance to genetic connectivity across the contiguous range of greater sage-grouse (as measured by “betweenness” calculated in Cross et al. 2018).

MISSOULA, Mont., May 10, 2018 – The Greater sage-grouse, once estimated to have a population of 16 million across the western United States, is now believed to number less than one million. The population decline is related to their habitat, much of which has been degraded by non-native grasses and fragmented by development. Because of the location-specific nature of their mating ritual, greater sage-grouse are particularly vulnerable to habitat disruption. New research builds the case for optimism for this species of concern. A new USDA Forest Service Rocky Mountain Research Station study, The genetic network of greater sage-grouse: range-wide identification of keystone hubs of connectivity, provides tools for decisionmakers to inform which areas of habitat are most critical to conserve, not just for the bird, but for other species as well.

For over a decade, a broad set of partners worked together to collect feathers from sage-grouse across their range. Researchers at the U.S. Forest Service Rocky Mountain Research Station genotyped 5,950 individual sage-grouse using DNA collected from these samples. Scientists set out to map the mating areas called “leks” and identify the birds that use each of these areas. They grouped 1,200 leks into “nodes,” or a collection of leks, within the network of greater sage-grouse. The nodes were then categorized as “hubs” or spokes” based on their importance to facilitating gene flow within and across the range of sage-grouse. To visualize how these nodes relate to one another, think of the leks as airports: Denver, Colorado would be a “hub,” while a smaller town, like Bozeman, Montana, would be a “spoke” served by the hub. In terms of sage-grouse, hubs foster gene flow out to the spokes. If a hub were to be lost, the birds in the connected spokes would be at risk of genetic isolation.

This research can help land managers prioritize where to locate a proposed development or management action in light of its proximity to leks of high importance to genetic connectivity — and how restoration or an easement could reconnect the birds with their leks. By ranking the importance of hubs across the range, partners can prioritize where to invest conservation dollars in order to ensure a resilient and viable sage-grouse population.

“Say you have a high-priority area for genetic connectivity, and over the years conifers have encroached due to fire suppression. To help preserve that genetic hub, you might consider cutting back the conifers,” said Todd Cross, lead author on the study from the USDA Forest Service Rocky Mountain Research Station.

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Hubs were found across the species’ range, with concentrations in north-central Montana, southern Wyoming, northeastern Colorado, northwestern Utah, and central Idaho. The study showed that this research can also be applied to many of the 350-plus species that call the sagebrush home. According to Cross, “The greater sage-grouse is a great poster-child for western landscapes but there are other animals like winter mule deer and elk, antelope and pygmy rabbits that may benefit from this research. Through this research, we’re getting a picture of how genetics fit into the landscape of the West.”

Related Publications:

Cross, Todd B. ; Schwartz, Michael K. ; Naugle, David E. ; Fedy, Brad C. ; Row, Jeffrey R. ; Oyler-McCance, Sara J. , 2018

The Rocky Mountain Research Station is one of seven units within the U.S. Forest Service Research and Development. RMRS maintains 14 field laboratories throughout a 12-state territory encompassing parts of the Great Basin, Southwest, Rocky Mountains, and the Great Plains. RMRS also administers and conducts research on 14 experimental forests, ranges and watersheds and maintains long-term research databases for these areas. While anchored in the geography of the West our research is global in scale. To find out more about the RMRS go to 
www.fs.fed.us/rmrs. You can also follow us on Twitter at www.twitter.com/usfs_rmrs.

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