Distributing Defenses: How Resource Defendability Shapes the Optimal Response to Risk
Affiliation
Department of Ecology and Evolutionary Biology, University of ArizonaIssue Date
2022
Metadata
Show full item recordPublisher
University of Chicago PressCitation
Donaldson-Matasci, M. C., Powell, S., & Dornhaus, A. (2022). Distributing Defenses: How Resource Defendability Shapes the Optimal Response to Risk. American Naturalist.Journal
American NaturalistRights
© 2022 The University of Chicago. All rights reserved. Published by The University of Chicago Press for The American Society of Naturalists.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
Many organisms divide limited defenses among heterogeneous assets. Plants allocate defensive chemicals among tissues differing in value, cost of defense, and risk of herbivory. Some ant colonies allocate specialized defenders among multiple nests differing in volume, entrance size, and risk of attack. We develop a general mathematical model to determine the optimal strategy for dividing defenses among assets depending on their value, defendability, and risk of attack. We build on plant defense theory by focusing on defendability, which we define as the functional relationship between defensive investment and successful defense. We show that if hard-to-defend assets cost more to defend, as assumed in resource defense theory, the optimal strategy allocates more defenses to those assets, regardless of risk. Inspired by cavity-nesting ants, we also consider the possibility that hard-to-defend assets have a lower chance to be successfully defended, even when defensive investment is high. Under this assumption, the optimal response to elevated risk is to reduce defensive allocation to hard-to-defend assets, a conservative strategy previously observed in turtle ants (Cephalotes). This new perspective on defendability suggests that in systems where assets differ in the chance of successful defense, defensive strategies may evolve to be sensitive to risk in surprising ways. © 2022 The University of Chicago. All rights reserved.Note
12 month embargo; published: 31 May 2022ISSN
0003-0147DOI
10.1086/718715Version
Final published versionae974a485f413a2113503eed53cd6c53
10.1086/718715