WHEN DOES MORPHOLOGY MATTER

The performance of an organism is the crucial link between its phenoty pe and its ecological success. When does an organism's morphology affe ct its performance? Quantitative mechanistic analyses of how function depends on biological form have shown that the relationship between mo rphology and performance can be nonlinear, context-dependent, and some times surprising. In some cases, small changes in morphology or simple changes in size can lead to novel functions, while in other cases cha nges in form can occur without performance consequences. Furthermore, the effect of a specific change in morphology can depend on the size, shape, stiffness, or habitat of an organism. Likewise, a particular ch ange in posture or behavior can produce opposite effects when performe d by bodies with different morphologies. These mechanistic studies not only reveal potential misconceptions that can arise from the descript ive statistical analyses often used in ecological and evolutionary res earch, but they also show how new functions, and novel consequences of changes in morphology, can arise simply as the result of changes in s ize or habitat. Such organismal-level mechanistic research can be used in concert with other tools to gain insights about issues in ecology( e.g. foraging, competition, disturbance, keystone species, functional groups) and evolution (e.g. adaptation, interpretation of fossils, and origin of novelty).