1. What is the Island Rule in evolution?
The Island Rule describes the evolutionary tendency of animals living on islands to evolve into either giants or dwarfs compared to their mainland relatives. Small species often grow larger, while large species tend to shrink.
2. Why do animals evolve into giants or dwarfs on islands?
On islands, limited resources and space often cause large animals to become smaller (dwarfism) due to the need to adapt to scarcity. Conversely, smaller animals may grow larger (gigantism) because of reduced competition and a lack of predators.
3. Can you give examples of island dwarfism and gigantism?
Examples of dwarfism include extinct dwarf elephants and hippos that once lived on Mediterranean islands. Examples of gigantism include the St Kilda field mouse, which is twice the size of its mainland ancestor, the dodo of Mauritius (a giant pigeon), and the Komodo dragon.
4. Does island dwarfism occur in India?
An example of island dwarfism in India is seen in the Nicobar Islands, where certain deer species, such as the Nicobar spotted deer, are smaller than their mainland counterparts, likely due to limited resources and island-specific conditions.
5. What factors influence island gigantism and dwarfism?
The size and isolation of islands, along with climate and seasonality, affect the extent of dwarfism and gigantism. Smaller, more remote islands have more pronounced effects, especially on mammals and reptiles.
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