A diminutive leaf-eared mouse has made its home atop a 6,739-meter Andean volcano, thriving in extreme conditions where the air is thin, temperatures are freezing, and survival is challenging for humans. Researchers, including a team from McMaster University in Hamilton, Ontario, have unveiled the biological adaptations that enable this feat. Published in the journal Science, the study reveals that Andean leaf-eared mice at high altitudes can efficiently generate heat despite low oxygen levels. They have also evolved to process toxic compounds found in their food.
Known as Phyllotis vaccarum, these mice inhabit the summit of Volcán Llullaillaco on the Chile-Argentina border, where oxygen levels are significantly reduced compared to sea level. The species boasts the widest elevation range among mammals, ranging from sea level along Chile’s northern coast to heights exceeding 6,700 meters in the Andes. Researchers conducted genome comparisons and laboratory tests on mice from various elevations, demonstrating that highland mice outperform their lowland counterparts in heat production under low-oxygen conditions, a critical advantage in frigid environments.
The study highlights the highland mice’s muscular energy production efficiency, particularly in supporting shivering to maintain body warmth in cold climates. Mitochondria in their hind-leg muscles exhibit enhanced oxygen and nutrient conversion into energy compared to lowland mice, owing to a higher lipid fuel utilization capacity. This adaptation ensures a sustained energy supply for shivering, crucial for survival in harsh conditions.
Interestingly, genetic analysis revealed that these mice have evolved to detoxify harmful compounds present in the limited vegetation available at high elevations. Despite the challenging environment and sparse food sources, these mice have adapted to thrive in extreme conditions, showcasing the remarkable resilience of life forms in seemingly inhospitable habitats. The findings underscore the continuous surprises of evolution and the resilience of life in diverse environments across the planet.
