Experimental Support for Aposematic Coloration in the Salamander Ensatina eschscholtzii xanthoptica: Implications for Mimicry of Pacific Newts

A field experiment was conducted to test the hypothesis that the plethodontid salamander Ensatina eschscholtzii xanthoptica benefits from aposematic coloration. Under field conditions, clay models painted to resemble E. e. xanthoptica were attacked significantly less often than models lacking the supposed aposematic colors. In addition, the head region of models was attacked significantly more frequently than random, suggesting the models were perceived as prey items. These results are consistent with the hypothesis that E. e. xanthoptica is a mimic of highly toxic Pacific Newts in the genus Taricha. The significance of the E. e. xanthoptica phenotype for the ring species biogeographic scenario and future research directions are briefly discussed.