Research


What we have been taught in our introductory level Ecology courses regarding mutualisms is a lie...  Mutualisms seldom involve a 1-on-1, +/+ relationship; a darker, more sinister reality exists.  Most mutualisms involve a suite of characters; some good, some bad, but most lie somewhere in the grey.  These characters typically cheat, punish,and steal from their partners (just like any good relationship) and are typically associated with several different partners at any given time.  This is a far cry from our happy bee friend pollinating a bright, colorful flower while a smiling sun watches adoringly that we learned about in general ecology.  

Broadly, I have interests in all things mutualistic.  Being a tad more specific, I'm interested in community interactions within mutualisms.  More specific yet, I'm interested in how belowground symbiotic communities structure themselves on, in, and around plant roots.  As if this wasn't cool enough on its own, I'm also interested in how environmental stress (climate change factors, drought, nutrient limitation, etc.) will alter the dynamics of these complex relationships.  Although I'm primarily interested in mycorrhizal fungal communities, I have several projects involving rhizosphere bacterial communities.  
            

My broad interest in belowground mutualisms is exemplified by the wide array of projects that I'm currently working on.

1) To investigate the balance of abiotic and biotic factors that are structure mycorrhizal fungal communities, I'm investigating fungal communities along an elevational gradient at RMBL (Rocky Mountain Biological Lab).  The argument of biotic versus abiotic factors has been a long-fought debate in ecology for several decades, but does the either/or debate really matter?  It seems commonplace that some balance between abiotic and biotic factors ultimately control community structure.  One of the main questions I'm interested in pursuing is: Does the balance of abiotic vs biotic factors change as you move along an elevational gradient?  It seems unlikely, that communities are structured by the same factors at the bottom of a mountain to the top.  

2) In conjunction with fellow UT graduate student Quentin Read, we will be installing warming chambers in our gradient plots.  This will allow me to assess how natural mycorrhizal communities will respond to warming along the elevational gradient.  Studies that have been done of mycorrhizal fungal communities and warming have shown mixed results of response, suggesting that response of fungal community is likely dependent on local fungal pool. Changes to fungal community will likely have large consequences for supporting plant community.

3) With global change, plant species are migrating to higher elevations and latitudes (29m / decade) as well as altering their phenology (leaf out 2.5-5 days / °C earlier over the past 30 years). Plants shifting to an earlier phenology may leave their localized, co-adapted symbiotic partners behind. Although we have evidence of disjuncts in aboveground plant-pollinator and plant-herbivore symbiosis in response to changing climatic conditions, there are limited empirical data exploring the ability of mycorrhizal fungi to either: acclimate to new climatic conditions, associate with new plant hosts, or shift phenology towards more suitable growing conditions.

4) Soil has long been recognized as a heterogenous environment that supports a diverse group of organisms that thrive within a wide variety of niches.  But, thinking smaller scale, can we think of a single plant root as heterogeneous environment that can provide different niches for symbiotic microbes?  Using a mixed bag of microbes, I'm exploring whether symbiotic bacteria will colonize different portions of the root space, rhizosphere space, or hypho-sphere space.

5) It has been recognized that mycorrhizal relationships can no longer be thought of as a plant and fungal relationship.  Several studies have demonstrated that fungus and plant communication and facilitation is mediated by a guild of microbes termed mycorrhizal helper bacteria.  Although several authors have shown the importance of these microbes to the overall functioning and facilitation of mycorrhizal relationships, they have been relatively ignored within ecological studies.  I'm trying to understand how presence of all three partners changes what we understand about mycorrhizal relationships.

There is a pretty good chance that their are a few more projects included since I have finished writing this section...... If you have any questions or if you are interested in collaborating, send me an email.

Prior to starting my PhD in Tennessee, I worked primarily with AM fungi in the labs of James Bever at Indiana University working on a variety of projects from: measuring the influence of heavy deer herbivory upon AMF spore community composition, spore community structure under different host plants in a grassland reconstruction, to using 454 to address sporulation patterns across grasslands from throughout North America, and finally measuring mycorrhizal impact on boreal peatland plant productivity (in a nutshell, exploring fungal communites in a wide variety of systems).  Prior to my time at IU, I worked with Stephen Bentivenga at the University of Wisconsin Oshkosh where I completed my B.S. and M.S.  There I learned AMF spore taxonomy and worked on AMF spore community composition within a reconstructed grassland that was manipulated by using plant seeding mixtures of differing diversity, nested within the seeding treatments, was a nitrogen and fungicide addition.  Additionally I conducted a project that measured the influence of AMF on competitive interaction between Indiangrass and big bluestem. 


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