What is Allen's Rule ?

Explanation

### Step-by-Step Solution:

1. **Definition of Allen's Rule**: Allen's Rule is an eco-geographical principle that describes how the physical characteristics of warm-blooded animals are influenced by the climate in which they live.

2. **Origin of the Rule**: The rule was formulated by the scientist Joel Asaph Allen in 1877.

3. **Key Concept**: According to Allen's Rule, animals that are adapted to cold climates tend to have shorter limbs and bodily appendages compared to those adapted to warmer climates.

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