Since prey size preference in snakes is generally proportional to body size, small snakes may be better adapted to take small prey. In tiger snakes, insular dwarfism occurs on islands where available prey is restricted to smaller sizes than are normally taken by mainland snakes. ДЄmong carnivores, the main factor is thought to be the size and availability of prey resources, and competition is believed to be less important. Smaller size is also advantageous from a reproductive standpoint, as it leads to shorter gestation periods and generation times. Eventually food sources replenish, and the survivors flourish. Population declines and, as smaller animals need fewer resources and smaller territories, they will survive longer. A process where only smaller animals trapped on the island survive, as food declines to a borderline level. One is based on the idea that a smaller territory means a smaller food supply. There are several proposed explanations for the mechanism which produces such dwarfism. On the other hand large species may evolve smaller bodies because food supplies are limited. Insular dwarfism is one aspect of the more general ' island rule': when mainland animals colonize islands, small species tend to evolve larger bodies, perhaps because the island may not have key predators. This may include caves, desert oases, isolated valleys and isolated mountains ('sky islands').

This process may occur not only on traditional islands, but also in other situations where an ecosystem is isolated from external resources and breeding. Examples include dinosaurs, like Europasaurus, and modern animals such as elephants and their relatives. This process has occurred many times throughout evolutionary history. The main cause is their population's range being limited to a small environment, and this happens most often on islands. The same process can happen in evolution on a mainland: an example is the evolution of the dwarfed marmosets and tamarins among New World monkeys. Island dwarfism, or insular dwarfism, is the reduction in size of large animals over a number of generations. The skeleton of a dwarf elephant from Crete

Floris expanded vs evolved