Body build and temperature tolerance: an experimental analysis of ecological 'rules'
Riesenfeld, A.
Acta Anatomica 107(1): 35-45
1980
ISSN/ISBN: 0001-5180 PMID: 7405512 Document Number: 156962
Anthropological theory suggests that the 2 factors that primarily determine thermoregulation in human populations are body size and body proportions according to the ecological rules of Bergmann and Allen, respectively. To test the validity of these ideas, Buffalo and Fisher rats were submitted to various levels of heat and cold. The 2 strains were chosen because they demonstrate maximum differences in body size and body proportions in domesticated rats. Allen's rule (shorter extremities are associated with colder climates and longer ones with warmer climates) has only a limited applicability under conditions of heat and none in cold. Bergmann's rule [i.e., within a polytypic homeothermic species, body size of subspecies increases with decreasing mean habitat temperature] is well substantiated by experimental data in heat and in cold. Nutrition is one of the most important factors influencing thermoregulation, but an extremely high degree of individual variation in temperature tolerance is found even under conditions of maximum homozygosity. The basic physiological processes of thermoregulation are sufficiently similar in human and nonhuman homeotherms to justify the extrapolation from one to the other.