Meeting Abstract

36.3  Thursday, Jan. 5  Indian summer: photoperiod alters thermally induced plasticity in life history and morphological traits. HAHN, D.A.*; CLEMMENSEN, S.F.; University of Florida; University of Tennessee dahahn@ufl.edu

It is well known that temperature can have substantial effects on morphological and life history traits, like body size and growth rates, especially in ectotherms. Photoperiod covaries seasonally with temperature in temperate regions, and photoperiod is often a reliable cue for inducing seasonal plasticity. Yet the effects of photoperiod on thermally induced reaction norms are often not considered. We highlight examples of how photoperiod can alter thermal reaction norms for body size, body composition, and thresholds for life history transitions from our own work on dormancy responses in moths and flies, as well as work on other ectotherms from the literature. We provide a framework for including photoperiodic effects in thermally induced reaction norms and discuss cases where this approach may be most useful for uncovering mechanisms that favor the evolution of adaptive seasonal plasticity in temperate environments.