Bergmann's rule

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Related to Bergmans rule: Gloger's rule

Bergmann's rule

(bûrg′mənz)
n.
The principle that in wide-ranging, warm-blooded animal species, individuals living in a cold climate tend to be larger than individuals of that same species living in a warm climate.
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Bergmann's rule

a rule stating that individuals from populations of warmblooded species of animals (HOMOIOTHERMS) which occur in cooler climates tend to be larger on average than individuals of the same species in warmer climates. This is because the surface area/volume ratio in large animals is smaller, so that heat loss is consequently reduced. The rule is named after the German biologist W. Bergmann, and was formulated in 1847. See also ALLEN'S RULE.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005