Global warming is causing chipmunks in the High Sierra to seek higher, cooler ground as the average temperature in the Yosemite region has increased by about 5.4 degrees over the past 100 years, a study from the University of California Berkeley revealed, according to an article published by Summit Voice.

At the turn of the 20th century, alpine chipmunks were sighted at elevations of 7,800 feet, according to research conducted by Joseph Grinnell, UC Berkeley’s first director of the Museum of Vertebrate Zoology, and colleagues. Now, the chipmunks appears to be moving to even higher elevations, shifting its range upward by about 1,640 feet.

According to the study, the chipmunks’ habitat has become more divided, resulting in small, isolated populations that are becoming genetically impoverished.

“Climate change is implicated as the cause of geographic shifts observed among birds, small mammals and plants … Under continued warming, the alpine chipmunk could be on the trajectory towards becoming threatened or even extinct,” study lead author Emily Rubidge, who conducted the research while earning a Ph.D. at UC Berkeley’s Museum of Vertebrate Zoology and the Department of Environmental Science, Policy and Management, said, according to Summit Voice.

Alpine chipmunks are high-elevation creatures so it’s not surprising that they would be more sensitive to global warming, the researchers said, according to Summit Voice.

According to the UC Berkeley News Center: “To test the genetic impact from that loss of geographic range, researchers compared genetic markers from 146 modern-day alpine chipmunks with those from 88 of their historical counterparts. Samples were collected from seven paired sites throughout Yosemite.

“As a control, the researchers also looked at the genetics – both historic and modern – of lodgepole chipmunks (Tamias speciosus), a lower elevation species that had not changed its range over the past century.

“The analysis of genetic markers revealed a significant decline in “allele richness” among the recently sampled alpine chipmunk populations compared with their historic counterparts. Moreover, the researchers noted that the modern chipmunks were more genetically differentiated across sites than in the past, a sign of increased fragmentation in the alpine chipmunk population.

“In comparison, there were no significant changes in genetic diversity detected among the lodgepole chipmunks, a species found at elevations from 4,900 to 9,800 feet.”

Justin Brashares, associate professor in the Department of Environmental Science, Policy and Management, told Summit Voice: “Much of what we read and hear about the effects of climate change on biodiversity is based on model projections and simulations, and these models typically involve many moving parts and lots of uncertainty. Thanks to the baseline provided by Joseph Grinnell’s pioneering efforts in the early 20th century, we are able to go beyond projections to document how climate is altering life in California. The research led by Emily is novel and important because it shows empirically that climate change has led to the loss of genetic diversity in a wild mammal over the last several decades.”

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