Morphological Consequences of Developmental Plasticity in Rana temporaria are not Accommodated into Among-Population or Among-Species Variation

Environmental induced developmental plasticity occurs in many organisms and it has been suggested to facilitate biological diversification. Here we use ranid frogs to examine whether morphological changes derived from adaptive developmental acceleration in response to pool drying within a species are mirrored by differences among populations and across species. Accelerated development in larval anurans under pool drying conditions is adaptive and often results in allometric changes in limb length and head shape. We examine the association between developmental rate and morphology within population, among populations in divergent environments, and among species inside the Ranidae frog family, combining experimental approaches with phylogenetic comparative analyses. We found that frogs reared under decreasing water conditions that simulated fast pool drying had a faster development rate compared to tadpoles reared on constant water conditions. This faster developmental rate resulted in different juvenile morphologies between the two pool drying conditions. The association between developmental rate and morphology found as a result of plasticity was not mirrored by differences among populations that differed in development, neither was it mirrored among species that differed in development rate. We conclude that morphological differences among populations and species were not driven by variation in developmental time per se. Instead, selective factors, presumably operating on locomotion and prey choice, seem to have had a stronger evolutionary effect on frog morphology than evolutionary divergences in developmental rate in the ranid populations and species studied.Peer Reviewe