Ecosystem effects of intraspecific variation in a color polymorphic amphibian

An emerging consensus suggests that evolved intraspecific variation can be ecologically important. However, evidence that evolved trait variation within vertebrates can influence fundamental ecosystem-level processes remains sparse. In this study we sought to assess the potential for evolved variation in the Spotted Salamander (Ambystoma maculatum) to affect aquatic ecosystem properties. Spotted Salamanders exhibit a conspicuous polymorphism in the color of egg masses—some egg masses are clear, others are white. We assessed the potential for morph frequency variation in the Spotted Salamander (Ambystoma maculatum) to influence fundamental physiochemical and ecosystem properties: dissolved organic carbon, conductivity, acidity, and primary production with a mesocosm experiment. By manipulating morph frequency across a range of larvae densities, we were able to show that density and morph variation are ecologically relevant. However, the effects of density and morph differed. Population density reduced dissolved organic carbon and increased primary production while mesocosms stocked with the white morph tended to have higher dissolved organic carbon and conductivity. Thus, while an adaptive significance of jelly coloration remains hypothetical, our results show that morphs differentially influence key ecosystem properties–dissolved organic carbon and conductivity.

Methods
Data were generated from a two-stage experiment. Stage one was a common garden-rearing experiment used to generate hatchling salamander larvae later used in a mesocosm experiment. The experiment was conducted in Boone, North Carolina, USA in spring and summer 2022.

Detailed methods are reported in the manuscript and the electronic supplementary materials.