Leaf-eared birds, small rodents, can survive at altitudes above 6,000 meters above sea level. Researchers analyzed the DNA of individuals found high in the Andes and compared them with the genes of animals from the lower parts of the mountains – as it turned out, they belong to the same population, which means that some leaf-eared birds consciously climb to inhospitable peaks. It remains a mystery why they do this.
In 2020, Jay Storz from the University of Nebraska found a yellow-leafed leaf-eared moth while on a hike (Phyllotis vaccarum), a small rodent from the hamster family. There would be nothing strange about this, if it weren’t for the place where he was currently staying – the peak of the Llullaillaco volcano in the Andes, which rises to a height of 6,739 meters above sea level. The peak is located on the volcanic plateau of Puna de Atacama, located on the border of Chile and Argentina. It’s a place so inhospitable and oxygen-poor that… NASA used them to simulate conditions on Mars.
Further research showed that this was not an isolated case, and other individuals also lived high in the mountains. As a study published in the journal “Current Biology” shows, these small rodents still have a lot of secrets.
A big, happy family
In addition to living leaf-eared lizards, scientists managed to find and preserve the remains of 13 animals on the volcanic slopes. They were mummified in the cool, dry atmosphere of the Andes, which meant their DNA was perfectly preserved. This made it possible to compare their genes with those found in individuals living in the lower parts of the mountains.
– Our genomic research shows that rodents from the peaks and those living in lower places are one big, happy family – explained Storz, the lead author of the study.
The team found that the two pairs found on one volcanic peak were closely related – possibly siblings or parents and children. Another regularity was also noticed: there were both males and females among the mummies. This indicates that leaf-eared birds may not only explore the Andes, but somehow live on the mountain slopes.
– These are exactly the results we would expect if we were collecting a population sample from a habitable area – explained the researcher.
The limits of endurance
As Storz explained, in the Andes, extreme Martian conditions prevail even at the foot of the mountains, and on the peaks it is even more difficult.
– It is simply amazing that any animal, let alone warm-blooded mammals, can survive and function in such an environment. When you experience it all firsthand, it’s even more impressive, he said.
Scientists now want to determine how animals adapt to living in extreme conditions. For this purpose, a breeding of leaf-eared lizards collected from various places in the Andes was established, and then the rodents were acclimatized to conditions simulating Puna de Atacama. The study is ongoing.
One more question remains – why do animals decide to live at such altitudes? The research team has one hypothesis. Like most small rodents, leaf-eared birds spend a lot of time, energy and attention avoiding predators. Even in the inaccessible region of Puna de Atacama, many dangers await them: foxes, pumas and predatory birds.
But can the extremely difficult conditions on the peaks – almost complete lack of water, little food, risk of freezing to death – really be worth escaping from predators?
– If you’re hiding on top of a 6,000-meter-high volcano, you’re safe in that respect at least, but there are other things you need to worry about. Why they climb to these extreme heights is still a mystery, Storz added.
University of Nebraska-Lincoln
Main photo source: Marcial Quiroga-Carmona