"island rule" meaning in English

{
  "etymology_text": "From being an empirical rule applied to evolution on islands.",
  "head_templates": [
    {
      "args": {
        "1": "?"
      },
      "expansion": "island rule",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Evolutionary theory",
          "orig": "en:Evolutionary theory",
          "parents": [
            "Biology",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "The principle of biology that states that populations isolated onto islands may undergo evolution towards dwarfism or gigantism to better conform to available resources"
      ],
      "id": "en-island_rule-en-noun-QaOFRfL~",
      "links": [
        [
          "evolutionary theory",
          "evolutionary theory"
        ],
        [
          "biology",
          "biology"
        ],
        [
          "population",
          "population"
        ],
        [
          "evolution",
          "evolution"
        ],
        [
          "dwarfism",
          "dwarfism"
        ],
        [
          "gigantism",
          "gigantism"
        ]
      ],
      "qualifier": "evolutionary theory",
      "raw_glosses": [
        "(evolutionary theory) The principle of biology that states that populations isolated onto islands may undergo evolution towards dwarfism or gigantism to better conform to available resources"
      ],
      "synonyms": [
        {
          "word": "Foster's rule"
        }
      ]
    }
  ],
  "word": "island rule"
}

{
  "etymology_text": "From being an empirical rule applied to evolution on islands.",
  "head_templates": [
    {
      "args": {
        "1": "?"
      },
      "expansion": "island rule",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English nouns with unknown or uncertain plurals",
        "en:Evolutionary theory"
      ],
      "glosses": [
        "The principle of biology that states that populations isolated onto islands may undergo evolution towards dwarfism or gigantism to better conform to available resources"
      ],
      "links": [
        [
          "evolutionary theory",
          "evolutionary theory"
        ],
        [
          "biology",
          "biology"
        ],
        [
          "population",
          "population"
        ],
        [
          "evolution",
          "evolution"
        ],
        [
          "dwarfism",
          "dwarfism"
        ],
        [
          "gigantism",
          "gigantism"
        ]
      ],
      "qualifier": "evolutionary theory",
      "raw_glosses": [
        "(evolutionary theory) The principle of biology that states that populations isolated onto islands may undergo evolution towards dwarfism or gigantism to better conform to available resources"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "Foster's rule"
    }
  ],
  "word": "island rule"
}