Andean Mouse Survives Extreme Altitude

Biologists studying the Andean leaf-eared mouse, Phyllotis vaccarum, in the Andes mountains of South America have identified genetic adaptations allowing it to thrive at altitudes exceeding 6,700 meters. These mice live where temperatures are almost constantly below freezing and oxygen levels are only 44% of those at sea level.

Researchers from the University of Nebraska compared the genomes of mice from varying altitudes, discovering that while genetically similar, high-altitude populations possess key genetic differences enabling them to tolerate extreme conditions. The team found the mice exhibit increased heat production, heightened muscle activity, and remarkably efficient mitochondria, cellular powerhouses, allowing them to maintain body temperature despite low oxygen.

Surprisingly, the mice do not rely on increased hemoglobin levels, a common adaptation to altitude, but instead use a combination of physiological and genetic adjustments. These rodents also metabolize toxins found in the limited edible plants available at high altitudes, highlighting the harshness of their environment. Jay Storz and his team are now comparing adaptations across multiple high-altitude species to determine if similar mechanisms are at play.