Dynamic energy budget modelling of anuran life-history with account for individual variability in developmental rates

The decline of amphibian populations is a major concern in environmental protection, and likely involves multiple stressors, such as loss of habitat, temperature changes, chemical exposure and pathogens. Mechanistic models can be helpful to understand and predict amphibian response to multiple stressors, but amphibian physiology and life history are unique, requiring adaptions to generic models. Thus, the goal of this study was to implement and test a whole life-cycle Dynamic Energy Budget (DEB) model for amphibians and test its ability to reproduce and predict metamorphosis traits. The model includes a dedicated reserve compartment for the biomass that is used to fuel metabolic processes during metamorphic climax, and a decline in feeding rates for metamorphizing individuals. While the model formulation was partially guided by a minimization of the number of parameters, a global sensitivity analysis indicated nevertheless that a wide range of metamorphosis traits could be produced. The model reproduced larval growth and metamorphosis traits in Discoglossus galganoi with account for individual variability in the time to reach metamorphosis with high accuracy. Based on the D. galganoi parameters as a reference, we fitted the model to a subset of the same life-history data for Pelophylax perezi larvae, attempting to predict the duration of metamorphosis and wet mass at the end of metamorphosis. For P. perezi , the duration of metamorphosis was slightly under-predicted, and the wet mass at the end of metamorphosis was under-predicted by a factor of 0.6. Given that D. galganoi and P. perepzi are rather distinct in their developmental strategies and stem from different families of anurans, this result does show potential for possible model applications to anuran species with poorer data coverage, in particular if data from a more closely related reference species is available. Open questions remain with respect to implementing the fasting period during metamorphic climax in models based on DEBkiss, while maintaining the fit to metamorphic mass change data.