How Andean Leaf-Eared Mice Thrive in Extreme Conditions
July 19, 7:00 PM
A new study reveals how Andean leaf-eared mice (Phyllotis vaccarum) manage to live on volcanic peaks in the Andes, at altitudes above 6,700 meters where oxygen is scarce and temperatures are freezing. These rodents have adapted to their harsh environment by packing their muscles with mitochondria, burning fat instead of carbohydrates, and carrying genetic changes that help them break down toxins from poisonous plants.
These mice inhabit the volcanic summits of the Andes, where oxygen levels are half of what they are at sea level. British zoologist Oldfield Thomas first discovered this species in 1912 at an elevation exceeding 6,700 meters. Their range spans from Chile's coastline all the way up to the peaks of Andean volcanoes. Researchers collected over 160 mice, including specimens from the summit of Llullaillaco volcano, where oxygen is just 44% of normal.
Evolutionary Adaptations in the Mice
The muscles of these high-altitude rodents are packed with mitochondria, allowing them to use energy more efficiently and stay active under severe conditions. Graham Scott, a professor of animal physiology at McMaster University, noted:
'They're more like a marathon runner than a sprinter. Their muscle cells are crammed with mitochondria, which lets them keep generating heat and staying active for longer.' - Graham Scott
The study also found that Andean leaf-eared mice burn fat rather than carbohydrates, a key evolutionary adaptation. 'At first, we focused on the most obvious challenges like low oxygen and cold, but there were important factors we didn't expect, particularly how these animals handle their diet,' Scott added. Scientists identified signs of selection in genes responsible for breaking down plant toxins, which helps the rodents survive on these extreme high volcanoes.
The findings were published in the journal Science. They highlight the unique adaptations that allow Andean leaf-eared mice to thrive in the incredibly harsh conditions of their habitat.
This research sheds new light on how animals adapt to extreme environments, offering insights that could be vital for understanding evolutionary survival mechanisms in similar settings. Studying these adaptations may also aid conservation efforts for biodiversity in the face of climate change and shrinking natural habitats.