Meeting Abstract
When an organism has multiple plastic traits, they can alter each other’s expression. This could occur, however, either because one trait changes the cues received from the environment that the other responds to or because it changes the reaction norm the other trait uses to respond to those cues. Battus philenor caterpillars we have previously established that a thermoregulatory color change reduces the use of thermoregulatory behavior, and we sought to test which of these mechanisms cause this effect. Our original demonstration that black caterpillars seek thermal refuges at lower environmental temperatures than red ones involved a field experiment with live caterpillars. In subsequent lab experiments, we have shown that this effect remains if intense light is used to heat the caterpillars; however, if this light is removed and caterpillars are heated by primarily by conduction, color no longer affects the refuge-seeking behavior. Additionally, color has no effect on the sensitivity of the caterpillar’s metabolism to temperature, a potential mechanism which would likely alter the thermoregulatory behavior’s reaction norm. As such, we find that the effect of color on thermoregulatory behavior is due to how it changes the cues which trigger color change (i.e., body temperature), rather than the reaction norm that responds to those cues. Cue-based interactions like this one are likely to be common in thermoregulation, and they also present a novel, within-generation consequence for any alterations an organism makes to its environment (i.e. niche construction). In other circumstances, both mechanisms presented here remain possible and need to be considered more broadly across additional species and ecological contexts.
