Andean Leaf-Eared Mice Set Altitude Record, Reveal Unique High-Altitude Adaptations

Andean leaf-eared mice (*Phyllotis xanthopygus*) have been documented at elevations exceeding 22,000 feet—about 6,000 feet higher than the world’s highest permanent human settlement. The highest-altitude specimen was collected in 2020 by a mountaineering research team, and the new study examined 167 individuals spanning the species’ full geographic range, from Chile’s coastal deserts to the icy peaks of the Andes.

Scientific American

Laboratory analyses showed that high-altitude mice possess an enhanced capacity for heat production, driven by distinctive skeletal-muscle modifications that enable vigorous shivering in freezing air. Genomic sequencing identified gene variants associated with hypoxia tolerance—similar to those found in other high-altitude vertebrates—and additional sequences that permit digestion of toxic desert plants common in the arid Andes. These dual adaptations address both the low-oxygen environment and the limited, chemically defensive food sources available at extreme elevations.

Scientific American

Researchers suggest that deciphering these mechanisms could inform medical strategies for human conditions involving oxygen deprivation. By comparing mouse physiology with human responses to hypoxia, the work may help guide the development of therapies for diseases such as chronic obstructive pulmonary disease and ischemic injury.

Scientific American

External experts note that while the study links genomics, physiology, and ecology, several aspects remain unresolved. Associate professor Jorge Salazar-Bravo (Texas Tech University) observes that “a few things are diluted,” indicating gaps in the integration of data streams. Co-lead author Schuyler Liphardt (University of Montana) emphasizes the need to identify the precise metabolic pathways and dietary triggers underlying the observed genetic signatures.

Scientific American

• “This study is focused on how they evolved the physiological ability to cope with the reduced oxygen availability and the constant freezing temperatures,” — Jay Storz, Evolutionary Biologist, University of Nebraska

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• “We’ve continually been surprised by the ability of these animals to live in these super hostile environments, and when you’re out there working, you have a really direct experience of how hostile those environments are,” — Jay Storz

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• “Beyond a “fascinating discovery about a weird animal,” Storz says, understanding the inner workings of these mice allows scientists to understand how other animals, including humans, might adapt to low-oxygen environments.” — Jay Storz

Scientific American

• “Each one of these units—the genomics and genetics and physiology—tells a good story, but it seems to me that a few things are diluted,” — Jorge Salazar-Bravo, Associate Professor of Biology, Texas Tech University

Scientific American

• “We don’t know the mechanism here; we don’t know the function there. And that’s what we want to go into further: digging into the specifics of how this actually works and what is happening here and ‘What are they eating?’ and what is inducing these kinds of things,” — Schuyler Liphardt, Bioinformatics Data Scientist, University of Montana

Scientific American