Mountain Wildlife - Mountain Geography: Physical and Human Dimensions - page 443

Thus, mammals appear to fall into two groups. Some species, such as mice, rats, and
man, show an increase in the number of red blood cells and the quantity of hemoglobin
at high altitudes. These are primarily low-altitude animals with the ability to acclimat-
ize and live successfully at high altitudes. The other group consists of species that have
been native high-altitude animals through geologic time, for example, certain rodents,
the Camelidae, and other hoofed animals such as the yak, sheep, and goats; these do
not display an increase in number of red cells or quantity of hemoglobin in their blood
(Bullard 1972). This approach has apparently been favored by long-term selection and
is viewed as adaptive. Although both approaches appear to achieve the same end, they
are not equally efficient: The former, based on the need for greater oxygen in the sys-
tem, is metabolically more expensive (Morrison 1964).
Clearly, animals deal with the stressful conditions and opportunities of high altitudes
in numerous ways. Some make the high mountains a permanent home and display elab-
orate adaptations to escape predators, reduce the effects of low temperature and high
snow accumulation, and deal with the brevity of the growing season and the seasonal
scarcity of food. Most modify and escape these negative factors through behavior, fol-
lowed by acclimatization and adaptations in their physiology and morphology. Similarly,
as discussed in Chapters 10 and 11, human populations also extend into the high moun-
tains, primarily through modification and amelioration of the environment, though there
are biological adaptations to mountains in some human populations.
References
Aldous, C. M. 1951. The feeding habits of Pocket gophers ( Thomomys talpoides moorei )
in the high mountain ranges of Central Utah. Journal of Mammalogy 32(1): 84-87.
Aleksiuk, M. 1976. Reptilian hibernation: Evidence of adaptive strategies in Thamnoplis
sirtalis parietalis. Copeia 1: 170-178.
Alexander, A. F., and Jensen, R. 1959. Gross cardiac changes in cattle with high moun-
tain (brisket) disease and in experimental cattle maintained at high altitudes. Amer-
ican Journal of Veterinary Research 20: 680-689.
Alexander, G. 1964. Occurrence of grasshoppers as accidentals in the Rocky Mountains
of northern Colorado. Ecology 45(1): 77-86.
Alexander, G., and Hilliard, J. R., Jr. 1969. Altitudinal and seasonal distribution of
Orthoptera in the Rocky Mountains of northern Colorado. Ecological Monographs 39:
385-431.
Allen, J. A. 1877. The influence of physical conditions in the genesis of species. Radical
Review 1: 108-140.
Andersen, D. C., Armitage, K. B., and Hoffman, R.S. 1976. Socioecology of marmots: Fe-
male reproductive strategies. Ecology 57(3): 552-560.
Andrewartha, H. G., and Birch, L. C. 1954. The Distribution and Abundance of Animals.
Chicago: University of Chicago Press.
Aranoff, S. 1989. Geographic Information Systems: A Management Perspective. Ottawa,
ON: WDL Publications.