Arguably, the process of adaptive ecological speciation and radiation has been the most important mechanism in contributing to the worlds immense biological diversity. Initial theoretical treatments of adaptive speciation made special mention of species interactions, namely interspecific competition, as an important source of divergent natural selection that ultimately contributed to the formation of novel ecological and species diversity. However, accumulating evidence suggests that mutualistic associations, especially those between microbes and insects, may be important in the process of adaptive speciation, as mutualists can act as sources of important phenotypic variation. In this dissertation, I investigate aspects of the interaction between the goldenrod-galling midge, <i>Asteromyia carbonifera</i>, and its fungal symbiont, <i>Botryosphaeria dothidea</i>, and attempt to relate the findings to ongoing evolutionary diversification within the species. First, a verbal theoretical treatment of how microbial mutualists could affect the process of adaptive speciation is put forth, using insects and their diverse microbial associates as examples. Second, I show by sterol-profile analysis that <i>A. carbonifera</i> appears to feed exclusively on its fungal associate, which may be important in opening nutritional ecological opportunity. Finally, I show that while the fungal associate mediates the observed phenotypic variation in gall morphology, it is the midge itself that is directly responsible for the ecologically important phenotypic variation. Moreover, the fungal associate does not exhibit the typical evolutionary signatures of a heritable mutualism. These data suggest that, for <i>Asteromyia carbonifera</i>, the fungal symbiont may indeed be a crucial player in the ongoing evolutionary radiation of its host, but the association does not appear to be a typical host-symbiont coevolutionary interaction.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-07272010-155621 |
| Date | 05 August 2010 |
| Creators | Janson, Eric Michael |
| Contributors | David E. McCauley, Patrick Abbot, Daniel J. Funk, John O. Stireman III |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-07272010-155621/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0016 seconds