Interacting Effects of Temperature and Food on Early Growth of Two Plethodontid Salamanders
An amphibian’s life history includes growth, development, and reproduction, which are fundamental to their population dynamics. Yet for many amphibians, we lack knowledge about the environmental factors affecting early growth, which can affect size at metamorphosis, age and size at sexual maturity, and clutch sizes. In this study, we investigated the growth of young salamanders of two species of plethodontid salamanders with different life cycles, Plethodon cinereus (direct development) and Eurycea cirrigera (biphasic). To examine the interaction between body size and environmental conditions, we conducted a laboratory experiment on both species using a factorial design, with two food treatments crossed with two temperature treatments. Early growth patterns differed for both species of salamanders. Overall, both species grew at a slower rate when food was limited. Eurycea cirrigera displayed non-linear growth, which varied among treatments. In Plethodon cinereus, average growth in length was negligible, and mass declined at low temperatures. The results of this study suggest that effects of environmental change on salamander populations are complex and will vary according to species life history, food availability, and climate.
Mean total length (mm) of Eurycea cirrigera in two food treatments, crossed with two temperature treatments (high temperature [HT], high food; high temperature, low food; low temperature [LT], high food; low temperature, low food). The blue line represents the low-temperature treatment, and the red line represents the high-temperature treatment. Shaded areas represent 95% confidence intervals around the GAMM trend parameters.
Mean mass (g) of Eurycea cirrigera in two food treatments, crossed with two temperature treatments (high temperature [HT], high food; high temperature, low food; low temperature [LT], high food; low temperature, low food). The blue line represents the low-temperature treatment, and the red line represents the high-temperature treatment. Shaded areas represent 95% confidence intervals around the GAMM trend parameters.
Mean SVL (mm) of Plethodon cinereus in two food treatments, crossed with two temperature treatments (high temperature [HT], high food; high temperature, low food; low temperature [LT], high food; low temperature, low food). The blue line represents the low-temperature treatment, and the red line represents the high-temperature treatment. Shaded areas represent 95% confidence intervals around the GAMM trend parameters.
Mean mass (g) of Plethodon cinereus in two food treatments, crossed with two temperature treatments (high temperature [HT], high food; high temperature, low food; low temperature [LT], high food; low temperature, low food). The blue line represents the low-temperature treatment, and the red line represents the high-temperature treatment. Shaded areas represent 95% confidence intervals around the GAMM trend parameters.
Contributor Notes
Associate Editor: J. M. Davenport.