Science

This mouse breaks a new height record!

Despite its 55 grams and its fearful air, the mouse with the yellow ears seems to adapt perfectly to extreme temperatures and lack of oxygen: Scientists have just caught a living specimen at 6,739 meters above sea level on the summit of the Llullaillaco volcano in the Andes. We still don’t understand how it feeds.

How far will it go After the little yellow-billed mouse (also known as the Patagonian fur lip mouse) was seen at 6,200 meters above sea level in 2013 (see article below), Phyllotis xanthopygus) was captured in February 2020 at 6,739 meters above sea level on the island volcano Llullaillaco, a volcano in the Andes, on the border between Argentina and Chile. On the tracks of rodent The University of Nebraska biologist Jay Storz and his mountaineering friend Mario Perez Mamani have successfully filmed and captured the mouse that sought refuge under a rock for many years.

Cold, lack of oxygen and food: extreme living conditions

No one has seen anything in the Himalayas mammal dare you so high And with good reason: The environment is particularly hostile, with extreme temperatures, a very small amount ofoxygen and the complete lack of food. Some birds and mammals have adapted their physiology carry life up high, but cannot live permanently without vegetation or insects. What does the little mouse eat, which is more than 2,000 meters above the last blade of grass?

The question remains open. Either way ” This new discovery shows that we underestimate that physiological limits small mammals », Writes Jay Storz in his report, which was published on the scientific platform bioRxiv. Because biologists rarely set off the highest peaks in the world, other living things may have found protection there looks.

This small extreme mammal lives at more than 6,000 meters above sea level

Articles by Celine Deluzarche published on 08/01/2019

What is gray or light beige, weighs 55 grams, has big bushy ears and is located at 6,000 meters above sea level? Answer: The bored mouse, also known as the Patagonian fur mouse (“”). This animal lives in the Andean Cordilleras in places where there is no vegetation left.

In 2013, the American emergency doctor Matt Farson couldn’t believe his eyes At 6,200 meters above sea level, it encounters a small rodent that runs beneath it nose while trying to climb Llullaillaco, a summit of 6,739 m in the Andean Cordilleras on the border between Argentina and Chile. The slopes of the volcano, still active, are known as one of the most inhospitable places in the world, with a Oxygen content twice less than at sea level, a lunar landscape that is flooded by gusts Windstemperatures can drop to -50 ° Cwinter and climb up to 32 ° C on the rocks in summer.

A habitat that extends from 0 to 6,200 meters

Matt Farson barely has time to photograph the animal and shares his find with Scott Steppan, a mouse specialist at the University of South Florida. The latter suspects that it is a gel-drilled mouse, a species certainly known for live in height, but also found in fields at sea level. ” This means that it is also the animal that can live with the greatest height difference, the scientist enthuses. It is just extraordinary “” A second expedition organized in 2016 confirms this assumption. The researchers succeeded in finding another specimen and taking samples of it earth about the construction, its analysis DNA corresponds exactly to that of Phyllotis xanthopygus.

The previous record holder, the Big Ear Pika (Ochotona macrotis) has already been observed at 6,120 meters above sea level and 80 meters below sea level. The difference is that the gel-drilled mouse seems to live permanently at these heights. The small size of the observed specimen suggests that they are young mice from a colony and not a single subject who happened to venture here.

A specially adapted physiology

But how can such a puny animal survive the extreme conditions at these heights? Jay Storz, a biologist from the University of Nebraska, has studied extensively the white-footed mouse, the North American equivalent of the yellow-tailed mouse, which lives up to 4,000 m above sea level. “” These animals survive thanks to a number ofphysiological adjustments, as a metabolism slowed muscles and a specialized cardiovascular system “He explains National Geographic. The drilled mouse also has a lot brown adipose tissuewhich ensures Thermogenesis especially in hibernation animals.

However, there are unanswered questions. What can the rodent eat well at a height where the only vegetation consists of rare lichen spots on the rocks? Scott Steppan suggests that the small animal could benefit from wind-borne food waste, but this seems to be insufficient. So little mouse in any case, this is additional evidence that living things have unimagined adaptability.

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