Reassessment of the environmental mechanisms controlling developmental polyphenism in spadefoot toad tadpoles. 
Identifying the environmental mechanism(s) controlling developmental polyphenism is the first step in gaining a mechanistic and evolutionary understanding of the factors responsible for its expression and evolution.  Tadpoles of the spadefoot toad Spea multiplicata can display either a "typical" omnivorous or a carnivorous phenotype.  Exogenous thyroxine and feeding on conspecific tadpoles have been accepted as triggers for development of the carnivorous phenotype on the basis of a series of studies in the early 1990s.  I repeated the thyroxine and conspecific-feeding assays and demonstrated that neither exogenous thyroxine nor feeding on conspecifics induces the carnivorous phenotype.  Previous researchers used simple ratio statistics to argue that field-collected carnivores and thyroxine-treated tadpoles are similar, and my results supported these claims if I used the same simple ratio methodology.  However, investigation of trait developmental trajectories and allometries for field-collected carnivores and thyroxine-treated and conspecific-fed tadpoles show that these phenotypes are profoundly different.