And blogging about! Obligatory readings of the day:
This research elegantly demonstrates that the evolution of just one character -- in this case, toxicity -- can profoundly affect the evolution of a suite of other characters, ranging from body size and behavioral traits to ecological niche.
Within species ... across clines or subspecies ... this raises very significant (and addressable) questions regarding adaptation in the genetic vs. the ontogenetic realms. If Allen's rule is primarily an ontogenetic effect in some species, one can still consider the possibility that it is adaptive, but the nature of adaptation becomes somewhat more nuanced. Which is appropriate, because adaptation is probably never as straight forward as the textbook version of it towards which we tend to gravitate.
Well, competitive exclusion matters. Which is why a) the giant spherical amoebas exist only where there are no snails and b) giant spherical bunnies of the arctic are actually polar bears!