The island rule: made to be broken?

[Tim Williams <twilliams_alpha@hotmail.com>]

This is plausibly relevant to dinosaurs, given that the issue of insular 
dwarfism has come up for European dinosaurs (e.g., _Europasasaurus_, 
_Magyarosaurus_, _Telmatosaurus_, _Struthiosaurus_).  This new Proc. R. Soc. B. 
paper says that the "island rule" is actually quite shaky.  (For mammals, 
anyway.)




Shai Meiri, Natalie Cooper & Andy Purvis (2007).  The island rule: made to be 
broken?  Proceedings of The Royal Society B. FirstCite Early Online Publishing 

Abstract: "The island rule is a hypothesis whereby small mammals evolve larger 
size on islands while large insular mammals dwarf. The rule is believed to 
emanate from small mammals growing larger to control more resources and enhance 
metabolic efficiency, while large mammals evolve smaller size to reduce 
resource requirements and increase reproductive output. We show that there is 
no evidence for the existence of the island rule when phylogenetic comparative 
methods are applied to a large, high-quality dataset. Rather, there are just a 
few clade-specific patterns: carnivores; heteromyid rodents; and artiodactyls 
typically evolve smaller size on islands whereas murid rodents usually grow 
larger. The island rule is probably an artefact of comparing distantly related 
groups showing clade-specific responses to insularity. Instead of a rule, size 
evolution on islands is likely to be governed by the biotic and abiotic 
characteristics of different islands, the biology of the species in
 question and contingency."

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