Mice live on the top of a volcano nearly 7000m high

Experts discovered that rats lived on the top of Llullaillaco, where trees could not grow, opening new research on adaptability in harsh environments.

A team at the University of Nebraska-Lincoln confirmed that Phyllotis xanthopygus is the highest living mammal in the world , IFL Science reported on March 24. The study is published in the bioRxiv database and is awaiting approval by the panel of experts.

Phyllotis xanthopygus mice cling to the gloves of scientists.(Photo: Marcial Quiroga-Carmona).

In 2013, the creature was first seen in Llullaillaco, the dormant volcano on the western edge of the Andes, the border area between Argentina and Chile. In February of this year, the team returned to Llullaillaco and captured several live specimens. In particular, the highest height they caught was 6,739 m.

Several reports have described the discovery of the large-eared pika rabbit (Ochotona macrotis) , a hamster-like animal, at an altitude of about 6,000 m in the Himalayas. However, scientists have never caught a living specimen at this height.

The environment atop Llullaillaco is extremely harsh. Phyllotis xanthopygus mice have to cope with the cold to -65 degrees Celsius, while living with 45% less oxygen than at sea level. Food is also particularly scarce because this altitude exceeds the "tree limit" , meaning the plant cannot survive.

The team believes that the rats eat insects and lichens, but have not found clear evidence. They hope to investigate further to see how they survive and thrive in such harsh environments.

"I have studied many creatures living at high altitudes and think that Phyllotis xanthopygus has developed special adaptations, including evolution of pulmonary heart function and metabolic mechanisms. I am very interested in find out what makes this mouse work in such a harsh place, " said Jay Storz, author of the study and an associate professor of biology at the University of Nebraska-Lincoln.