|Llamas are frequently used by physiologists to study hypoxic
stress due to their proven ability to live successfully at high
altitude. The lama genus is considered to have four species:
llama (L. llama), alpaca (L. pacos), guanaco (L. guanacoe),
and vicuna (L. vicugna) (Lama Information). Guanacos and
vicunas are rarely found in captivity, however the llama and alpaca have
been domesticated for approximately four thousand years (Walker et al.,
Image courtesy of Brian Pinkerton at Mount Lehman Llamas.
|Numerous physiological adaptations of llamas to decreased oxygen pressures have been found. The llama shows a shift to the left in the oxygen dissociation curve when compared to similar lowland animals. Specifically llamas have adapted by lowering the P50 value, therefore the llama will more easily obtain oxygen from a low pressure environment (Meschia et al., 1960). Research also suggests that llamas use erythrocytes with high hemoglobin concentrations which aids in the process of oxygen extraction (Lewis, 1976). Finally, llamas show an increased affinity for oxygen due to lowered concentrations of DPG (Meschia, 1960).|
|A graph demonstrating the leftward shift in the oxygen dissociation curve of the llama. The curve is compared to mammals (man, horse, and pig) native to lowlands, yet physiologically similar to the llama. Graph adapted from Hall et al. (1936).|
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Last Updated November 28, 1999