"Allen's rule" meaning in English

{
  "etymology_text": "Formulated by Joel Asaph Allen in 1877.",
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  "lang": "English",
  "lang_code": "en",
  "pos": "name",
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          "name": "English entries with incorrect language header",
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      "glosses": [
        "An ecogeographic principle broadly stating that animals adapted to cold climates have relatively short limbs. Specifically, homeothermic animals in hot climates have low volume-to-surface ratios, and homeothermic animals in cold climates have high volume-to-surface ratios, due to thermal adaptation."
      ],
      "id": "en-Allen's_rule-en-name-7XCz2vUW",
      "links": [
        [
          "ecogeographic",
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        [
          "principle",
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        [
          "homeothermic",
          "homeothermic"
        ]
      ]
    }
  ],
  "word": "Allen's rule"
}

{
  "etymology_text": "Formulated by Joel Asaph Allen in 1877.",
  "head_templates": [
    {
      "args": {},
      "expansion": "Allen's rule",
      "name": "en-proper noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "name",
  "senses": [
    {
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        "English entries with incorrect language header",
        "English eponyms",
        "English lemmas",
        "English multiword terms",
        "English proper nouns",
        "English uncountable nouns",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "An ecogeographic principle broadly stating that animals adapted to cold climates have relatively short limbs. Specifically, homeothermic animals in hot climates have low volume-to-surface ratios, and homeothermic animals in cold climates have high volume-to-surface ratios, due to thermal adaptation."
      ],
      "links": [
        [
          "ecogeographic",
          "ecogeographic"
        ],
        [
          "principle",
          "principle"
        ],
        [
          "homeothermic",
          "homeothermic"
        ]
      ]
    }
  ],
  "word": "Allen's rule"
}