Allen's rule


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Allen's rule

[′al·ənz ‚rül]
(vertebrate zoology)
The generalization that the protruding parts of a warm-blooded animal's body, such as the tail, ears, and limbs, are shorter in animals from cold parts of the species range than from warm parts.
References in periodicals archive ?
Conversely, the inverse association between the RPL and altitude appears to bear out Allen's rule (1877) that endotherms tend to have shorter appendages in colder climates.
Dr Symonds said Allen's rule has never been tested with this large a group of animals and was more anecdotal.
In summary, contrary to endotherms where the fitness consequences of body size and shape on heat loss are believed to have resulted in geographic patterns known as Bergmann's and Allen's rules, many ectothermic organisms display a pattern of body-size variation referred to as the converse of Bergmann's Rule (Masaki 1978) that is thought to have evolved in response to geographic patterns in season length.