Document: COL-3-23-1

A functional model for predicting patterns of within-plant resource heterogeneity and its consequences to herbivores.

ORIANS, C.M.* ¹ and C.G.JONES ²

Tufts University, Medford, MA, USA ¹
Institute of Ecosystem Studies, Millbrook, NY, USA ²

Abstract:
Numerous authors have argued that within-plant heterogeneity affects the interactions between plants and herbivores. Despite the few examples that clearly demonstrate its importance, general evidence in support of this hypothesis is limited. Is this because the significance of heterogeneity has been overstated or because we lack a framework for studying its effects? We argue for the latter largely because we do not have a clear understanding of what controls patterns of heterogeneity or how herbivores respond to that heterogeneity. In this talk we provide a general model for predicting both the patterns of heterogeneity and herbivore responses. First, we show that patterns of heterogeneity are controlled by species-specific differences in plant vascular architecture, by the distribution of plant resources (e.g., light and nutrients), and by patterns of damage by other organisms (e.g., herbivores and microbes). Second, we suggest that the effects of heterogeneity on herbivores depend upon: the foraging behavior of the herbivore, the presence or absence of natural enemies, and whether the average food quality on more heterogeneous hosts is higher, lower or similar to more homogeneous hosts. The advantage of our model is its recognition of multiple factors that affect patterns of within-plant heterogeneity and herbivore responses, each of which could be tested alone or in combination with others. We hope this model will encourage more rigorous investigation into the causes and consequences of within-plant resource heterogeneity.

Keywords: plant-hervivore interactions, within-plant heterogeneity,

This abstract is being presented at: 4:10 PM in session:
Symposium # 23: Why Variation is Not Just Noise: The Influence of Variability on Plant-Herbivore and Plant-Pathogen Interactions.