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New research shows that the animal's muscles are incredibly effective for its size, far more than other large animals.
This time of year, the temperature regularly reaches 104 degrees in northern Botswana. The grasses recede, forcing wildebeest herds to walk further and further away from their only water source to graze. The humidity drops to around 10 to 15%.
"It's not exactly Death Valley, but it's not that far," said Alan Wilson, a biologist whose research has focused on how wildebeest cope with such an inhospitable environment. . "They are at the forefront of physiology in terms of: how do they continue to survive?"
His research showed that these cow-like animals, also called wildebeest, have remarkable adaptations, allowing them to travel up to 50 km over 5 days without drinking water. They can do this because their muscles work incredibly effectively – much more than their size suggests.
"I do not think we'll reach 50 miles," said Dr. Wilson, referring to humans.
His study, published Wednesday in the journal Nature, showed that this efficiency means that wildebeest do not need to sweat as much to not gasp as much to release heat, even when they heat to a temperature higher than the temperature of their body.
"They do not have the problem of overheating or using water to cool down," said Andrew Biewener, a biomechanics expert at Harvard University who did not participate in the research. .
According to Dr. Biewener, the study helps to link muscle physiology and locomotion to animal behavior.
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Wildebeest are like very lean cows, said Dr. Wilson, professor of locomotive biomechanics at the Royal Veterinary College in London. "They are a little smaller than a cow and a lot lighter," he added. A typical cow weighs about 700 kilograms (1540 pounds) and a wildebeest about 200 kilograms (about 440 pounds).
Dr. Wilson flew over a wildebeest in helicopter in Makgadikgadi Pans National Park, pulling darts of tranquilizer in 20 of them. When six of the animals were briefly slaughtered, he took a small muscle biopsy for analysis in a London laboratory.
All 20 animals have been equipped with collars containing GPS, an accelerometer, a gyroscope, magnetometer, a humidity sensor and a thermometer measuring the combined effect of solar radiation, air temperature and air velocity on the animal. The necklaces were left for 18 months.
Large animals should have more efficient muscles than the smaller ones, which means that their muscle fibers have the ability to produce energy more efficiently. But the new study shows that efficiency is not limited to size. Previous research has revealed that the muscles of the rabbit were 27% effective and those of the mouse 34%.
New research has indicated that the muscles of large animals are generally more efficient, with cows at around 42% efficiency. Wildebeests have far exceeded their size with an efficiency of 63%.
Measurements of muscle efficiency are an important contribution to an area that has not calculated new species since the mice were first measured in 1994, said Robyn Hetem, a senior lecturer at the University of California. Witwatersrand in South Africa.
"Most of our knowledge of muscle fibers comes from this classic paper, she says noting that in order to calculate the amount of heat released by the muscles, it is necessary to measure the temperature in .001 degrees Celsius (or 32 degrees Fahrenheit).
Climate change is expected to make the environment of Botswana even more extreme, with a significant increase in temperature expected throughout Southern Africa.
Dr. Hetem said she was already worried about the wildebeest herds south of the animals studied by Dr. Wilson. In the 1960s, the government of Botswana built a veterinary fence in the north of the country to prevent wild antelopes from infecting cattle with foot-and-mouth disease.
But by protecting livestock, the government has prevented wildebeest from traveling through historic migration routes. It does not matter much in the usual years, she said, but led to massive mortality during particularly dry periods, said Dr. Hetem.
The wildebeest may be able to cope with some temperature increase, said Dr. Wilson, but noted that "it's a tough environment for all animals".
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