Antipredator responses of the morphs of an amphibian species match their diferential predation pressures

Abstract

Escape efciency typically relies on locomotor performance, which depends on morphology. Moreover, fight initiation distance (FID, the distance from an approaching predator at which a prey starts fight) is behaviourally adjusted to minimize the costs of escape. When conspecifcs with distinct heritable traits are subjected to diferential predator pressure, specialized antipredator strategies may evolve. Phenotypic variants associated to sex and other polymorphisms may be susceptible of sufering predator attacks to diferent extents. Herein, we used striped and mottled morphs of the polymorphic frog Discoglossus galganoi to test for diferences between morphs and sex in predation pressure and concomitant antipredator responses. Firstly, we used plasticine models to assess predation pressure (by a natural set of local predators ranging from snakes to birds and mammals) on both striped and mottled morphs. Then, we tested for diferences on morphology, locomotor performance, FID, and their interactions between morphs and sexes. Striped models were more often attacked, which suggests that striped frogs are under stronger predation pressure. Morphology was similar between morphs, and so was locomotor performance. However, FID was greater in striped than in mottled individuals. Contrastingly, sexes did not difer in FID, but males had longer limbs and greater locomotor performance than females, which is common in other taxa. Nonetheless, both sexes displayed similar FID. Finally, FID was greater in larger individuals, but unrelated to locomotor performance. These results support the hypothesis that diferent antipredator strategies are tuned to divergent predation risk sufered by sexes and morphs.