Foster's rule, also known as the island rule or the island effect, is an ecogeographical rule in evolutionary biology stating that members of a species get smaller or bigger depending on the resources available in the environment. For example, it is known that pygmy mammoths evolved from normal mammoths on small islands. Similar evolutionary paths have been observed in elephants, hippopotamuses, boas, sloths, deer and humans. It is part of the more general phenomenon of island syndrome which describes the differences in morphology, ecology, physiology and behaviour of insular species compared to their continental counterparts.
Garganornis ballmanni, a very large fossil goose from the Gargano and Scontrone islands of the Late Miocene
A biological rule or biological law is a generalized law, principle, or rule of thumb formulated to describe patterns observed in living organisms. Biological rules and laws are often developed as succinct, broadly applicable ways to explain complex phenomena or salient observations about the ecology and biogeographical distributions of plant and animal species around the world, though they have been proposed for or extended to all types of organisms. Many of these regularities of ecology and biogeography are named after the biologists who first described them.
Emery's rule states that insect social parasites like cuckoo bumblebees choose closely related hosts, in this case other bumblebees.
Lack's principle matches clutch size to the largest number of young the parents can feed
Image: Cambrian Trilobite Olenoides Mt. Stephen
Image: FMIB 35665 Common Crayfish (Astacus fluviatilis, Male) (cropped)
