Anti-predator behavior in two brown frogs: differences in the mean behaviors and in the structure of animal personality variation

Predation is a major source of selection and prey are known to modify their behavior depending on their past experiences and the current perceived risk. Within a species, variation in experience and in the response to perceived risk combine to explain variation in personality and individual plasticity. Between species, variation in personality and plasticity might also be the evolutionary consequence of different selective regimes. In this study, we describe the anti-predator behavior of two closely related brown frogs, Rana dalmatina and Rana latastei, and compare their structures of personality variation. We raised tadpoles in a common garden experiment with either fish, dragonfly larvae, or no predators. Tadpoles were then repeatedly tested in the presence of the three acute stimuli and their behavioral variation was described in terms of quantity and quality of movements and of path sinuosity. In these tests, tadpoles of both species and ontogenetic treatments responded flexibly to predators by moving less, faster, and with more tortuous movements, and tadpoles raised with predators tended to move even faster. Independent of the acute treatment, R. dalmatina moved more and faster than R. latastei and the differences were larger without than with predators, demonstrating its higher plasticity. At the individual level, the two species showed qualitatively similar but quantitatively different structures of personality variation. R. dalmatina, more active, faster, and more plastic than R. latastei, showed also higher repeatability and a larger behavioral variation both among and within individuals.Significance statementPredators are a major source of selection and preys have evolved the ability to flexibly respond to them. These responses often vary among species, because of their different evolutionary histories, and among individuals, because of their different experiences. We analyzed both these sources of behavioral variation in two closely related brown frogs, Rana dalmatina and R. latastei. We raised tadpoles either with or without predators and tested them in open field trials both with and without predators. The effects of the raising environment were similar in the two species, whereas the effects of the testing arena differed. Both species decreased activity and increased speed and sinuosity with predators, but R. dalmatina moved always more and faster than R. latastei and it showed higher plasticity, larger variation among and within individuals, and relatively higher values in repeatability.