A Substrate-Driven Plasticity Hypothesis for the Monterey Ensatina Salamander (Ensatina eschscholtzii)

Ahmed Rami Nasri

Abstract.—Phenotypic plasticity allows many amphibians, including several salamander species, to adjust skin luminance in response to background brightness. In habitats with heterogeneous substrates in color and brightness, such plasticity may generate substantial individual variation within a population. In a population of the terrestrial salamander Ensatina eschscholtzii, a recent study documented an unusually high frequency of atypical light phenotypes characterized by pink and orange dorsal coloration. This population occurs in a site dominated by extensive light-colored dune sand, suggesting a potential environmental influence on apparent coloration. We propose that substrate-driven plasticity may shift the apparent luminance of typical individuals toward lighter phenotypes in this species, and predict that this response occurs primarily in juveniles and diminishes through ontogeny.