Native desert bighorn sheep in ecologically intact areas are less
vulnerable to climate change

Date:
August 26, 2020
Source:
Oregon State University
Summary:
In the American Southwest, native desert bighorn sheep populations
found in landscapes with minimal human disturbance, including
several national parks, are less likely to be vulnerable to
climate change.



FULL STORY ==========================================================================
In the American Southwest, native desert bighorn sheep populations found
in landscapes with minimal human disturbance, including several national
parks, are less likely to be vulnerable to climate change, according to
a new study led by Oregon State University.


==========================================================================
The study, published in the journal Frontiers in Ecology and Evolution,
is one of the largest genetic studies conducted on desert bighorn
sheep. The researchers used genetic information from more than 1,600 individuals in 62 populations in and around 10 National Park Service
units in four states - - Arizona, California, Nevada and Utah. Park
service units include parks as well as other administrative units,
such as reserves and recreation areas.

The researchers found that the least vulnerable bighorn populations are primarily in and around Death Valley National Park and Grand Canyon
National Park. The results suggest that protecting these landscapes
should be a priority for native bighorn conservation, said lead author
Tyler Creech, an OSU graduate now at the Center for Large Landscape Conservation in Bozeman, Montana.

Meanwhile, the researchers determined that the populations with the
highest overall vulnerability are primarily located outside of national
park units in the southern Mojave Desert and in southeastern Utah.

In the study, the researchers analyzed the genetic structure and
diversity of bighorn sheep populations and how connected they are to
other populations, both genetically and geographically, and used that information to infer their vulnerability to a changing climate.

"We used DNA samples from bighorn sheep to tell us how genetically
diverse populations are," Creech said. "The populations that are less genetically diverse and less connected to their neighbors are more likely
to be negatively impacted by climate change." "Genetic diversity allows populations to adapt to new environments," said study co-author Clint
Epps, a wildlife biologist and associate professor in the Department of Fisheries and Wildlife in OSU's College of Agricultural Sciences.

"This study highlights the important role our national park units can play
in keeping these populations up as the climate changes." The researchers primarily used fecal pellet samples to obtain DNA from up to 85 individual bighorn in each population, and combined genetic datasets from multiple projects covering different portions of the study area, dating back to
2000. After the samples were processed and genotyped, they grouped the individuals into populations based on the locations where they were
sampled, then quantified the isolation and genetics of each population.

They also considered how exposure to harsher climatic conditions
within bighorn sheep habitat "patches" could influence populations' vulnerability. Desert bighorn sheep live in some of the hottest and
driest landscapes in the U.S., and climate modeling shows those areas
could get hotter and drier.

To assess climate change exposure, they used an index known as "forward
climate velocity," which indicates the speed at which species must migrate
to maintain constant climate conditions. They considered two greenhouse
gas emissions scenarios for the 2050s developed by the Intergovernmental
Panel on Climate Change, one that models moderate emissions and the
other that models high emissions.

"We believe this approach was suitable for assessing relative exposure
of desert bighorn populations across a large geographic range because
although temperature and precipitation are known to influence fitness of
desert bighorn sheep, the specific climatic conditions to which bighorn
are most sensitive are not fully understood and may vary geographically," Creech said.


========================================================================== Story Source: Materials provided by Oregon_State_University. Original
written by Chris Branam. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Tyler G. Creech, Clinton W. Epps, John D. Wehausen, Rachel
S. Crowhurst,
Jef R. Jaeger, Kathleen Longshore, Brandon Holton, William B. Sloan,
Ryan J. Monello. Genetic and Environmental Indicators of Climate
Change Vulnerability for Desert Bighorn Sheep. Frontiers in Ecology
and Evolution, 2020; 8 DOI: 10.3389/fevo.2020.00279 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200826151258.htm

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