Gazelles and other large desert-dwelling ungulates can live on very little food and water for long periods of time. How do they do it? This was an evolutionary mystery until recently, when researchers found that desert-dwelling gazelles survive by reducing their breathing frequency, thereby cutting fluid loss and decreasing their metabolic demands during periods of water deprivation. [pictured: Arabian sand gazelle, Gazella subgutturosa. Image: BCEAWS]
According to new research that focused on sand gazelles, Gazella subgutturosa, researchers found that these animals rely on two strategies to reduce their metabolic demands. First, sand gazelles' livers and hearts -- which are important determinants of metabolic rate -- decrease significantly in mass during four months of food and water restriction. However, because these animals must rely exclusively upon vegetation to meet their requirements for both food and water, the researchers found that their intestines did not decrease in mass. The gut walls are responsible in ruminants for 28-46% of whole-body protein synthesis, an energy demanding process.
The second strategy these animals use to reduce their metabolic demands was to store fat in their brains. The researchers were surprised to discover that the fat content of the animals' brains increased after a period of water deprivation. The brain is the other organ that makes heavy metabolic demands, and fats are rich in both water and energy.
"The deserts of the Arabian Peninsula are among the most austere of terrestrial environments, with low, unpredictable rainfall, and high ambient temperature," explain the authors. "The sand gazelle has evolved a remarkable capacity to reduce its evaporative water losses, which is likely a component of their success."
This research appears in the July/August issue of Physiological and Biochemical Zoology.
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And how did they determine the fat increase in the brain. Some benign way, I hope.
that is doubtful.
however, since these animals are rare and becoming rarer, and at least some of them are in a breeding program, i'd guess that the research was conducted on animals that had died (killed / culled / whatever) for other purposes. perhaps these animals were "hunted" by so-called "big game hunters" (snert) who paid an exorbitant price for the priviledge to shoot one or two individuals while they nibbled at a pile of apples? it's been known to occur for other rare captive-bred species.
if i remember to download the paper after it is online (finally), i can better answer your question, i think. remind me to check this out in a week or two, okay?