Island dwarfism

Island dwarfism, or insular dwarfism,^[1] is the reduction in size of large animals over a number of generations.

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. The smallest member is Cebuella pygmaea.^[2]

The main cause is their population's range being limited to a small environment, and this happens most often on islands. This process has occurred many times throughout evolutionary history. Examples include dinosaurs, like Europasaurus, and modern animals such as elephants and their relatives.

This process may occur not only on traditional islands, but also in other situations where an ecosystem is isolated from external resources and breeding. This may include caves, desert oases, isolated valleys and isolated mountains ("sky islands"). 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. On the other hand large species may evolve smaller bodies because food supplies are limited.

1. ↑ Prothero D.R. & Sereno P.C. 1982. (1982). "Allometry and paleoecology of medial Miocene dwarf rhinoceroses from the Texas Gulf coastal plain". Paleobiology. 8 (1): 16–30. doi:10.1017/S0094837300004322. JSTOR 2400564. S2CID 88464305.{{cite journal}}: CS1 maint: numeric names: authors list (link)
2. ↑ Perelman P. et al 2011. (2011). "A molecular phylogeny of living primates". PLOS Genetics. 7 (3): 1–17. doi:10.1371/journal.pgen.1001342. PMC 3060065. PMID 21436896.{{cite journal}}: CS1 maint: numeric names: authors list (link)