A comparative analysis of the adaptive developmental plasticity hypothesis in six Mediterranean anuran species along a pond permanency gradient

Abstract

Question: Is developmental phenotypic plasticity an adaptive trait and therefore more flexible in variable and unpredictable environments? Organism: The anuran larvae community encompassing Alytes obstetricans, Pelodytes punctatus, Bufo bufo, B. calamita, Hyla meridionalis, and Rana perezi. Methods: In the field, we examined the ecological breadth (spatial and temporal variability) of the six species along a pond permanency gradient in 240 ponds. In the laboratory, we measured developmental plasticity (time to and size at metamorphosis) of each species using two treatments: (1) constant water level and (2) drying treatment. A comparative analysis was undertaken of developmental plasticity and the function of species ecological breadth and their phylogenetic relationship. Results: Species that use a wide variety of habitats or unpredictable environments showed a greater plasticity of responses than those occurring in predictable habitats. At the two extremes of the hydroperiod (ephemeral and permanent ponds), specialist developmental phenotypes with limited plasticity occur, whereas species from variable habitats (temporary ponds) can be considered plastic strategists with asymmetric bet-hedging. Our results support the hypothesis that interspecific differences in developmental phenotypic plasticity are adaptive and are related to ecological breadth and unpredictability.