Oecologia (2012) 170:47–55 DOI 10.1007/s00442-012-2283-2 123 PHYSIOLOGICAL ECOLOGY - ORIGINAL RESEARCH Interactive inXuence of biotic and abiotic cues on the plasticity of preferred body temperatures in a predator–prey system Radovan Smolinský · Lumír Gvoqdík Received: 20 January 2011 / Accepted: 6 February 2012 / Published online: 23 February 2012  Springer-Verlag 2012 Abstract The ability to modify phenotypes in response to heterogeneity of the thermal environment represents an important component of an ectotherm’s non-genetic adaptive capacity. Despite considerable attention being dedicated to the study of thermally-induced developmental plasticity, whether or not interspeciWc interactions shape the plastic response in both a predator and its prey remains unknown. We tested several predictions about the joint inXuence of predator/prey scents and thermal conditions on the plastic- ity of preferred body temperatures (T p ) in both actors of this interaction, using a dragonXy nymphs–newt larvae system. DragonXy nymphs (Aeshna cyanea) and newt eggs (Ichthy- osaura alpestris) were subjected to Xuctuating cold and warm thermal regimes (7–12 and 12–22°C, respectively) and the presence/absence of a predator or prey chemical cues. Preferred body temperatures were measured in an aquatic thermal gradient (5–33°C) over a 24-h period. Newt T p increased with developmental temperature irrespective of the presence/absence of predator cues. In dragonXies, thermal reaction norms for T p were aVected by the interaction between temperature and prey cues. SpeciWcally, the pres- ence of newt scents in cold regime lowered dragonXy T p . We concluded that predator–prey interactions inXuenced ther- mally-induced plasticity of T p but not in a reciprocal fashion. The occurrence of frequency-dependent thermal plasticity may have broad implications for predator–prey population dynamics, the evolution of thermal biology traits, and the consequences of sustaining climate change within ecological communities. Keywords Aeshna · Biotic interactions · Preferred temperature · Reciprocal plasticity · Thermal acclimation · Triturus Introduction Thermally-induced plasticity (acclimation) together with thermoregulation and adaptive genetic change represent key components of the ectotherms’ capacity to cope with spatiotemporal variation in a thermal environment. Adap- tive thermal plasticity partially or completely buVers selec- tion pressures posed by novel thermal conditions by shifting trait means towards a new optimum (Ghalambor et al. 2007; Chevin et al. 2010). The plastic response thereby may aid in the persistence of isolated populations under a sustained temperature change. The thermal sensi- tivity of performance traits in many ectotherms can change due to variation in developmental and/or seasonal tempera- tures (Huey et al. 1999; Deere and Chown 2006; reviewed by Angilletta 2009). This suggests the widespread potential for physiological compensation in response to relatively fast temperature change. However, in contrast to thermal plasticity studies under controlled laboratory conditions, free-living organisms not only face thermal variation but also mutualists, parasites, predators, and competitors, which may inXuence the outcome of plastic responses within an ecological community. Despite recent urges to consider the role of biotic factors in thermal ecology studies to better predict the consequences of climate change on Communicated by Anssi Laurila. Electronic supplementary material The online version of this article (doi:10.1007/s00442-012-2283-2) contains supplementary material, which is available to authorized users. R. Smolinský · L. Gvoqdík (&) Department of Population Biology, Institute of Vertebrate Biology AS CR, Studenec 122, 67502 Kon5nín, Czech Republic e-mail: gvozdik@brno.cas.cz