Genetic And Temporal Variation In Resource Exchange Between An Ectomycorrhizal Fungus, Rhizopogon Occidentalis, And Seedlings Of Pinus Radiata

Various economic theories have been adapted to explain the evolutionary persistence of resource exchange mutualisms such as mycorrhizae. The ratio of resources exchanged is an important variable comto all these models. Measuring resource exchange ratios is the first step in testing the hypotheses predicted by these models and will provide insight into resource dynamics of mutualisms. We examined how the carbon, nitrogen and phosphorus resource exchange dynamics between Pinus radiata and an ectomycorrhizal fungus, Rhizopogon occidentalis, varied between native populations of Pinus radiata and over the first 64 weeks of the mycorrhizal mutualism. Using a mycocosm approach, the C:N and C:P exchange ratios were determined by comparing the amount of C respired by fungi and C assimilated in fungal biomass to the amount of N and P assimilated in plant tissues over a time period. Resource exchange was assessed at 8, 16, 32, and 64 weeks after inoculation for two Pinus radiata native populations. Resource exchange increased over time during the development of the mycorrhizal mutualism. Pine seedlings from the Cambria population transferred greater amounts of carbon to the ectomycorrhizal fungus, with the majority of this carbon being respired by fungal biomass. The ratio of resources exchanged did not vary over time or between pine populations, pointing to total resource fluxes as the potential mechanism behind changes in mycorrhizal fungal compatibility between populations of host plants.

Name thesis:degree_name

M.S. in Biological Science

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biology

Year dc:date.available

2016

Author dc:creator

• Meachum, Mariah

Contributors dc:contributor

• Jason D. Hoeksema
• John S. Brewer
• Clifford A. Ochs

• Biological Market
• Coevolution
• Ectomycorrhizal Fungi
• Monterey Pine
• Mutualism
• Resource Exchange
• Ecology and Evolutionary Biology

Repository record dc:identifier

https://egrove.olemiss.edu/etd/372

OAI identifier oai:identifier

oai:egrove.olemiss.edu:etd-1371