Context-dependent interactions in an ant-plant-hemipteran symbiosis
Abstract/Contents
- Abstract
- The cost-benefit outcomes of potentially mutualistic interactions between species can range on a continuum between mutualism and parasitism, depending on context. Here I use ecological, behavioral, physiological, theoretical, phylogenetic, and comparative approaches to understand the effects of context on the strength of an ant-plant-hemipteran mutualism. I examine how the strength of mutualism changes with variation in the density and behavior of individuals, the ontogenetic stage of individuals, resource availability in the surrounding environment, and the evolutionary history of a partner guild. The mutualism studied here occurs among the widespread neotropical tree Cordia alliodora, ants of the genus Azteca, and phloem-sucking scale insects of the superfamily Coccoidea. The ants live and tend scale insects inside specialized, hollow branch nodes of the tree, the scale insects excrete a concentrated sugar that forms a key component of the ants' diet, and the ants defend the trees against leaf-eating herbivores. In Chapter 1, I examine the indirect effects of increased densities of scale insects on the tree, and find that higher densities of scale insects increase the effectiveness of ant defense against leaf-eating herbivores. In Chapter 2, I investigate how ant defense of trees changes as trees and ant colonies grow in the course of ontogeny, and find that larger trees suffer from higher herbivore pressure and less effective ant defense. In Chapter 3, I consider the effects of water availability and covariation in tree growing-season duration on the mutualism, and find that as water availability increases, the strength of the mutualism decreases. In Chapter 4, I reconstruct the evolutionary history of the Azteca ant symbionts of the tree in Middle America, and, through the use of comparative methods, I find that the effectiveness of defense that ants provide to trees is conserved across the ant phylogeny. Taken together, these results show that biotic, abiotic, and evolutionary context can strongly affect the strength of an ant-plant-hemipteran mutualism, and that the direction of these effects may be predicted from key contextual variables.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2011 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Pringle, Elizabeth Greene |
|---|---|
| Associated with | Stanford University, Department of Biology. |
| Primary advisor | Dirzo, Rodolfo |
| Primary advisor | Gordon, Deborah, (Film producer) |
| Thesis advisor | Dirzo, Rodolfo |
| Thesis advisor | Gordon, Deborah, (Film producer) |
| Thesis advisor | Mooney, Harold |
| Thesis advisor | Ward, Philip |
| Advisor | Mooney, Harold |
| Advisor | Ward, Philip |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Elizabeth Greene Pringle. |
|---|---|
| Note | Submitted to the Department of Biology. |
| Thesis | Ph.D. Stanford University 2011 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2011 by Elizabeth Greene Pringle
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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