Gimme Shelter: Refuge Availability Interacts With Conspecific Density and Predator Chemical Cues to Affect Tadpoles and Metamorphs

ABSTRACT Predators may inflict non‐consumptive effects on their prey if their presence triggers the expression of defensive traits which consume resources to the detriment of other vital functions. Nonetheless, these effects can be milder if extrinsic factors, either biotic or abiotic, provide antipredator protection. I tested this hypothesis by rearing Iberian green frog ( Pelophylax perezi López‐Seoane 1885) tadpoles either singly or in groups, exposed or not to predator chemical cues, with or without a refuge. I also studied potential carryover effects of such treatments on the resulting metamorphs. Singly‐reared larvae exposed to predator chemical cues grew and swam faster, but group‐reared larvae did not follow these trends. Instead, they grew less deep tails as a response to predator chemical cues, which is against the general tendency of most anurans. Irrespective of density, the presence of a refuge induced shorter tails, and when combined with predator chemical cues, slower speed. Development was also faster, and time to metamorphosis shorter in singly‐reared individuals under predation pressure. Nonetheless, metamorphs did not follow the same patterns as larvae, and body size and locomotion were at their worst in group‐reared individuals which had no refuge while being exposed to predator chemical cues. Therefore, singly‐reared larvae exposed to predator cues seemingly invest more in predator avoidance than those reared in a group. Refuges relieve the investment in locomotion. The patterns found in metamorphs, however, suggest the stress resulting from the combination of competition by conspecifics, predation risk and the absence of a refuge echoes after metamorphosis. These results help disentangle the intricate connections between predation pressure as a stressor, refuge as a counter‐weight to it and the presence of conspecifics as a source of competition and a relief from pressure at different life stages.