Meeting Abstract
To maximize their fitness, organisms must perform many different tasks; however, the ideal phenotype for these tasks may differ, leading to functional tradeoffs. For example, an aposematic animal’s color is not only important to warn predators of their distastefulness, but also affects temperature. Nevertheless, many different traits can influence a given task, and thus to fully understand how these functions are performed, we must consider multiple traits. In addition to color, behavior can also influence both exposure to predators and temperature. We studied how color pattern and behavior interactively influence both temperature and predation risk in the caterpillars of Parasemia plantaginis (the wood tiger moth). We measured the effects of color and position (hidden vs exposed) on the temperature of live caterpillars, and measured the temperatures at which caterpillars of different patterns adopted different positions. We then used Parus major (great tits) as model predators to evaluate the how color and position interacted to determine relative predation risk. Live caterpillars hid very rarely except at high temperatures, an initially puzzling behavior which is explained by the fact that not only are exposed caterpillars warmer, but also safer from predators than hidden caterpillars. In contrast, the optimal color for thermoregulation and predator-avoidance did appear to differ, but their effect was much smaller than the effect of position. Ultimately we’ve shown that although functional tradeoffs do exist for some traits, for other traits the same phenotypic values may often be optimal for multiple functions. Both of these cases can occur in the same organism, and thus to fully understand how an organism meets an environmental challenge we should consider multiple traits and the other functions those traits may contribute to.
