Environmental effects on the ontogenesis of tadpole personality

Behaviours are highly plastic phenotypic traits whose variation depends on the short-term response toexternal stimuli (contextual plasticity) and on the long-term response to past experiences (develop-mental plasticity). Despite this great flexibility, behaviours often show individual differences that are consistent across time and context (i.e.‘animal personality’). By adopting a behavioural-reaction-norm (BRN) approach, we used a factorial common garden experiment to investigate the effects of contex-tual and developmental plasticity on the antipredator behaviour of treefrog tadpoles, Hyla intermedia.We raised 96 tadpoles from eight half sibefull sib families under different biotic (predation risk) and abiotic (shading) environmental conditions and described their activity and spatial behaviour inexperimental arenas with either a caged predator, a caged conspecific or an empty cage. Tadpoles raisedwith predator cues were always less active and stayed further away from caged predators than their predator-naïve siblings. Tadpoles raised in the shade were less active than those raised in the sun. Not only was the raising environment responsible for among-individual variation but it also acted at the within-individual level by affecting behavioural repeatability, which was higher in predator-naïve than in predator-experienced tadpoles. Besides the important role of the environment, this study also shows consistent variation in BRNs with body size and time: tadpoles became more active as they got larger and their activity increased with time in the presence of caged predators, decreased in the presence of empty cages and did not change with caged conspecifics. These results suggest that the effects of past and present experiences on tadpole behaviour vary with time as a consequence of growth and development.