9618702 SIH Predator-prey interactions play a central role in ecology and evolution. This proposal extends the existing understanding of predator-prey interactions in two important ways: 1) Most studies of prey responses to predators focus on one of several types of prey responses - e.g., antipredator behavior, or morphological defenses against predators, or chemical defenses. Prey, however, often show a suite of potentially inter-dependent antipredator responses. For example, prey that are well defended morphologically (e.g., that have a thick shell or spines) might show relatively little behavioral response to predators, while prey that are morphologically vulnerable might show a strong tendency to hide from predators. That is, the optimal prey behavior might depend on prey morphology and the cost of having an ineffective prey morphology can be mediated by compensatory behavior. Surprisingly few experiments have addressed the joint evolution of multiple prey responses to predators. 2) Similarly, most experimental studies of predator impacts on prey examine the effects of one predator on prey. In nature, however, most prey face multiple predators. The appropriate response to one predator might actually increase risk from another predator. Surprisingly little is known about how prey balance the conflicting selection pressures generated by multiple predators. This proposal will address the joint evolution of behavioral and morphological responses to multiple predators. The focal prey (a common, abundant snail) is a model organism for this study because: 1) it is known to show both behavioral and morphological responses to not just the predators, but also to chemical cues from both predators, and 2) it can be reared rapidly in huge numbers in the laboratory.
