Rising Above Climate Change

Pikas are small rabbit relatives that live at high elevations and are adapted to the cold.  As temperatures warm, lower elevations within their range are often becoming inhospitable.  Higher elevations are cooler, but oxygen is limited:  can pikas survive with less?   As keystone species and ecosystem engineers, pikas are fundamental to their environments.  Their long-term survival impacts ecological and geological networks and is of particular importance to landscape resilience as Anthropocene impacts bear down.

A new Stanford study reports potentially good news for pikas, showing that they may be able to acclimate to low oxygen levels (hypoxia) at high elevations by adjusting how their genes are expressed. The study, published in Plos One, shows that pikas can change their gene expression in response to hypoxia within a five-day period, suggesting they possess a mechanism allowing them to acclimate to vastly different elevations within their range in a very short time.  

The study builds on previous work showing significant differences in gene expressions of pikas living at different elevations in the Himalayas of India.  The field research was unable to quantify the potential of acclimation within an individual, which could only be tested using captive pikas in a controlled setting.  So, Solari and coauthor Elizabeth Hadly,  the Paul S. and Billie Achilles Professor in Environmental Biology in Stanford’s School of Humanities and Sciences, used an experimental framework to test the gene expression differences observed in the field.  They found that the same gene pathways, and even some of the exact same genes, were expressed at significantly higher levels in captive pika when exposed to hypoxia, corroborating the gene expression differences found in the field.

These results are somewhat hopeful for pikas and the ecosystems that depend on them.  But resilience to hypoxia is only one of the hurdles pikas face related to climate-induced range shifts in the Anthropocene, and their future is far from certain.

“Although we see this novel response to hypoxia among pikas separated from other mammals by at least 50 million years, differences in expression usually come at a cost somewhere else in the genome," Hadly said. "We have yet to determine what those costs are.”

Hadly is also a faculty director of Stanford’s Jasper Ridge Biological Preserve, a member of Stanford Bio-X and a senior fellow at the Stanford Woods Institute for the Environment. 

Mary Ellen Hannibal is a journalist and author, most recently of "Citizen Scientist:  Searching for Heroes and Hope in an Age of Extinction.” She is a winner of Stanford's Knight-Risser Prize for Western Environmental Journalism, a former Stanford media fellow and a member of the Hadly Lab.