Meeting Abstract
Conspicuously colored autotomous tails of many lizard species can direct predator attacks away from vital body areas thus increasing survival. However, many species transition from this conspicuous tail coloration to a cryptic phenotype. Why should some species ontogenetically abandon an advantageous phenotype in favor of another? Here, I seek to answer this question by empirically evaluating two hypotheses using the five-lined skink, Plestiodon fasciatus; (1) the increase in size from juvenile to adult causes a shift in primary predator, thus rendering the adaptive advantage null or even deleterious, and (2) the tail serves as a site for energy storage and it simply is too valuable to lose in adult lizards. Using museum collections, I show that the ontogenetic shift occurs consistently at or around 60mm SVL in P. fasciatus and I use clay models to test whether different predators target specific combinations of coloration and size. Increased caloric content of tail tissue in adults indicate that they do indeed incur a greater energetic loss through tail autotomy as they reach adulthood and these calories are manifest in lipid molecules most commonly used for energy storage in vertebrates. These data support both hypotheses and illustrate that, as P. fasciatus matures, the ecological benefit of tail autotomy decreases while the physiological cost of losing the tail increases. This provides compelling evidence that the interplay of ecological and physiological elements favor one phenotype in juvenile lizards and another in adults, thus driving the evolution of the ontogenetic shift.
