Allen's rule

American  

noun

1. Zoology. the generally observed tendency for the limbs and other appendages of animals living in a cold climate to be smaller or shorter than those of animals of the same species living in a warm climate.

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Allen's rule Scientific  

/ ăl′ənz /

1. The principle holding that in a warm-blooded animal species having distinct geographic populations, the limbs, ears, and other appendages of the animals living in cold climates tend to be shorter than in animals of the same species living in warm climates. Shorter and more compact body parts have less surface area than elongated ones and thus radiate less body heat. Allen's rule is named for the American zoologist Joel Allen (1838–1921).

2. Compare Bergmann's rule

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Example Sentences

See Examples For:

Allen's rule

Known as Allen's rule, it holds that, generally speaking, animals' appendages evolve to increase in size as the temperature around them also increases.

From Salon ● Sep. 22, 2021

According to a recent paper published in the journal "Trends in Ecology & Evolution," Allen's rule is manifesting itself in a number of animals because of climate change.

From Salon ● Sep. 22, 2021

This particular manifestation of Allen's rule also speaks to the way that climate change threatens biodiversity.

From Salon ● Sep. 22, 2021