Island rule

The tendency for large animal species to evolve smaller bodies and small species to evolve larger bodies on islands than on mainland areas.

Insular dwarfism: The evolution of smaller body size in large animals isolated on islands. It is the island rule’s size-reduction pattern for large-bodied animals.
Sicilian dwarf elephant: An extinct small elephant that lived on Sicily during the Pleistocene. Its reduced size is a classic case of island dwarfism.
J. Bristol Foster: A British ecologist whose 1964 study proposed a broad pattern of island mammal body-size evolution. Foster’s comparative analysis helped establish the island rule.
Island rule debate: Scientific disagreement over how consistently island mammals follow size-dependent evolutionary trends. Studies differ on whether the rule is general or driven by particular taxa and islands.
Island ecology: The study of interactions among organisms and environments on islands. Body-size shifts can reshape ecological roles within island communities.
Island gigantism: The evolution of unusually large body size in small animals isolated on islands. It is the island rule’s size-increase pattern for small-bodied animals.
Flores giant rat: An extinct large rodent known from the Indonesian island of Flores. Its large size illustrates the island rule’s increase among small mammals.
Van Valen's island rule: Leigh Van Valen’s 1973 formulation of size evolution in island mammals. Van Valen named and developed the pattern after Foster’s earlier work.
Body size evolution: Evolutionary change in the size of organisms or populations over generations. The island rule is one proposed recurring pattern within body-size evolution.
Extinction: The permanent loss of a species when its last living individual dies. Island-adapted giants and dwarfs can be especially vulnerable to rapid environmental change.

Linked from 14 pages