Mountain Wildlife - Mountain Geography: Physical and Human Dimensions - page 442

FIGURE 8.20 Snow algae in the high Cascades, Oregon. These algae accumulate in large numbers in
the spring as the snow melts, turning pockets and depressions a deep red color. This is known as
“watermelon snow” because of its distinctive color and odor. (Photo by L. W. Price.)
These differences in approach may be accounted for by two distinct processes: accli-
matization and adaptation. Both meet the requirements of high altitudes, but the former
is an adjustment or distortion of an existing pattern, whereas the latter is achieved
through long-term selection and development. Acclimatization operates at the individu-
al level on a short-term basis, whereas adaptation operates at the species or population
level through time. A few wild mountain animals do display an increase in production
of red blood cells and hemoglobin (Kalabukov 1937; Hock 1964c), but these occur in
mountains where there is direct contact between valleys and peaks, facilitating inter-
mixture. The Andes and trans-Himalaya, however, present broad areas at high altitudes
which support a stable population separated from lowland habitats by barriers (Mor-
rison 1964). The animal populations in smaller dissected mountains are apparently dis-
playing acclimatizations to altitude rather than adaptations, while populations native
to the higher and more massive uplands have developed their abilities through isola-
tion and evolution, and their characteristics are viewed as adaptations (Morrison 1964).
It has been suggested that even these mammals probably increased production of red
cells and hemoglobin upon first inhabiting the mountain area but, through time, this re-
sponse was replaced by increased blood-plasma volume (Bullard 1972). It is unfortunate
that the native highland animals most thoroughly studied are the rodents and camelids,
since the rodents are essentially preadapted to lack of oxygen because of their ability
to live underground and thus avoid costly flight from predators, while the camelids pos-
sess a number of unusual adaptations as a family even at sea level (Chiodi 1970-1971).