Allen's rule is an ecogeographical rule formulated by Joel Asaph Allen in 1877, broadly stating that animals adapted to cold climates have shorter and thicker limbs and bodily appendages than animals adapted to warm climates. More specifically, it states that the body surface-area-to-volume ratio for homeothermic animals varies with the average temperature of the habitat to which they are adapted.
Eskimo Group by photographer William Dinwiddie (1894)
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)
