Allometry as a fundamental mechanism linking evolutionary and ecological pattern in vascular plants

• Brian J. Enquist

Abstract
Traditionally, allometry has not been as important to the study of anatomy, physiology, and ecology as it has been in animal research. In animal studies, biological allometries can usually be characterized as quarter-power scaling relationships. The fact that quarter-power allometries emerge at multiple levels of biological organization (physiology, populations, life-histories) strongly suggests that one or a few critical mechanisms might link pattern and process within and between these levels. Recently, in collaboration with G. B. West and J.H. Brown, I have proposed a general hypothesis by which to mechanistically view biological allometries. This model is a deliberate oversimplification, however, we believe it captures the salient mechanisms dictating biological allometry. Most importantly, extensions of this model can accurately account for several allometric scaling relationships in vascular plants. Perhaps its biggest insight is that although plant and animals differ, allometrically they share numerous quarter-power allometric scaling relationships. The underlying assumption of this work is that allometry offers a window by which one can critically investigate fundamental mechanisms influencing plant structure, function, and evolution. I propose to explore and test the specific predictions of this model in vascular plants by using various empirical measurements of vascular anatomy and physiology, tied with computer simulation. The proposed research will specifically test the role of vascular systems in dictating plant architecture, evolution, and constraining ecological patterns in local communities. Overall, the project represents a unique and strongly multidisciplinary approach to basic biological questions. It will permit the examination of these questions over evolutionary instead of historical time spans. Insights gained from this proposal are likely to yield creative and predictive results pertaining to the movement of resources in the ecosystem and the extrapolation of plant form and ecology in paleoenvironments.