JACKSON, Wyo. — While pikas have been labeled by research as happiest in the country in Grand Teton National Park (GTNP), increasingly frequent temperature and water-
availability extremes are notable risks to their survival. Uniquely, pikas’ comparatively low genetic diversity gives them both a substantial disadvantage locally and potential advantage range-wide in the face of climate change.
Erik Beever, a research ecologist for the U.S. Geological Survey’s (USGS) Northern Rocky Mountain Science Center who’s currently performing research on American pikas in GTNP, says that while cheetahs have famously low levels of genetic diversity due to population bottlenecks, some populations of pikas have even lower genetic diversity than that.
“Pikas have the lowest genetic diversity of any mammal,” Beever tells Buckrail.
Beever credits this low genetic diversity to pikas’ often small genetic neighborhoods; they rarely make long-distance journeys and have minimal gene flow outside of their isolated rockpile, or individual talus patch.
The Ecological Society of America (ESA) calls pikas notably inbred “to an unusually high degree.”
Long-distance movements are even rarer in places that are hotter and drier, so pikas living in such places tend to have particularly low genetic diversity locally.
But Beever says that because pikas exist across one-third of North America and typically don’t move very far, across the entire species there’s actually a lot of genetic diversity that collectively exists across these dispersed populations.
According to Beever, genetic diversity is important for providing species with greater opportunity for resilience to future climate change. Beever says that this genetic diversity across the species’ range allows for “portfolio effects,” comparing genetic differences across the species’ geographic range to a retirement plan where a diversified variation of options minimizes the risk of total collapse.
“The likelihood of any particular [pika] population having the requisite diversity to handle new changes is very low, but as a species the likelihood that there are going to be some populations able to handle a given stressor is high,” Beever says.
Beever emphasizes that pika resilience is critical to local ecosystems. Pikas have been called “ecosystem engineers” due to their patterns of selectively eating some but not other plant species and their urinating and defecating patterns that locally change nutrient availability. They’re also part of multiple food pyramids.
Pikas have often been termed as ‘early-warning indicators’ because they are uniquely positioned to be researched in relation to climate change. Unlike almost every other mammal critically threatened with loss of habitat due to human behavior, Beever says the amount and spatial arrangement of pika habitat is relatively unchanged over time. He credits this to the fact that their high-altitude, rocky talus habitat is not desirable for human development or land uses.
This unchanging distribution of talus habitat allows scientists to isolate aspects of temperature and water availability as most important to pika disappearances from certain areas. In this way, pikas give early warning signs of regions that are not bioclimatically suitable for survival and may present issues for other wildlife.
But Beever says so far in GTNP, pikas still occur in almost all of the Park with little evidence of decline. Whereas in other regions, Beever is able to compare the factors that exist in the places pikas used to be versus where they persist, the Tetons present a region where, so far, pikas are still able to thrive.
Data on this year’s low snowpack and how it may be affecting the local pika population is not yet available.
