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Maron Lab



John Maron
Professor and Principle Investigator

Division of Biological Sciences

Phone: (406) 243-6202



Lauren Waller
Ph.D. student

Division of Biological Sciences


I am interested in the interactions between plants and their root-associated fungi. Plants associate with multiple microbial partners in their roots. Pathogenic fungi harm plants by feeding on their tissues, while mutualists, such as mycorrhizal fungi offer multiple benefits to plants, including nutrient delivery, protection from stress and pathogen protection. My research focuses on the ecological and evolutionary consequences of these interactions and revolves around three main areas:

Evolutionary persistence of the plant-mycorrhizal mutualism

What explains the evolutionary persistence of a mutualism that consists of beneficial as well as uncooperative partners? Natural selection should favor the symbionts that gain the greatest benefit for the smallest investment. Plant responses to mycorrhizal fungi range along a continuum from positive to negative, suggesting that some partners are more mutualistic than others. Using the plant-mycorrhizal system, I am investigating how mutualist partners can persist in the face of cheaters.

Mycorrhizal fungal ecology

There is no one-size-fits-all mycorrhizal fungal partner. Instead, AM fungal species vary in the type and magnitude of benefits they offer to plants. The fungal partner that is beneficial in one ecological context may be much less beneficial in another. My research investigates how this context dependency influences the distribution of AM fungi across a gradient of fungal pathogen pressure.

Invasive species

Invasive species often experience fewer negative soil feedbacks than native species. The Enemy Release Hypothesis, often invoked to explain this release from the negative effects of soil biota, states that invaders experience successful range expansion because they have been released from the specialist pathogens they evolved with in their home range.  However, far less is known about the interactions between plants and generalist fungal pathogens or mycorrhizal fungi. Do invasive species gain a greater benefit from the pathogen protection offered by mycorrhizal fungi than native species? Do invasive genotypes pay a reduced cost of association with mycorrhizal fungi than genotypes from the native range?

Katie Baer
Ph.D. student

Division of Biological Sciences


I started as a PhD student in the fall of 2011.  My own work is situated at the confluence of several disciplines, including pollination biology, plant-herbivore interactions, and population and community ecology.  Specifically, I’m interested in understanding the relative roles of biotic and abiotic environmental conditions in determining patterns of plant presence at the geographical scale.  It is generally assumed that distributional ranges (both local and geographic) are driven primarily by abiotic conditions, but research suggests that these factors may act indirectly.  This raises the question, “What is the role of biotic interactions for determining where a species is found and where it is not?”  The implications for the answer are huge: in order to effectively model changes in distributions resulting from changing climate, an understanding of the interacting roles of abiotic and biotic factors is crucial.  In an applied sense, the answer to this question will help managers to better understand the conditions that make a habitat ideal for an organism, and use this information in their attempts to establish effective preserves for threatened and endangered species.

My dissertation research focusses on the interaction of both positive and negative biotic factors and abiotic factors in determining the northern distributional limit of the Utah milkvetch (Astragalus utahensis).  This species occurs from southern Utah to southeastern Idaho, with the center of its distribution in northern Utah.  Using several field sites in northern Utah and southeastern Idaho, I am attempting to understand how herbivore pressure, pollen limitation, and interactions with soil pathogens and mutualists change from the center to the edge of the distributional range of this species, and whether this change in their roles is tied to decreasing water availability from the center to the northern edge of the range.  This work involves the use of a variety of methods, from demographic analyses using matrix models and greenhouse studies of growth rate to reciprocal transplants both within and outside the distributional range.  The outcome of this research will provide one of the first tests of the role of biotic interactions in determining geographic-scale distribution.

Loralee Larios
Post-doctoral associate

I am a community ecologist who is broadly interested in understanding the mechanisms that contribute to plant community composition and species coexistence. My interest in these dynamics is driven by how we can use this information to inform successful management and restoration practices. My dissertation research explored several processes, specifically competition for multiple resources, plant-soil feedbacks and disturbance, governing the invasion of exotics, the invasion resistance of native grasslands and the coexistence between native and exotic species within California grasslands. For my post-doctoral work I will be investigating how generalist herbivores (specifically herbivorous voles and granivorous mice) influence recruitment and ultimately the composition of species and traits within local plant communities. My approach consists of a combination of manipulative field and greenhouse experiments and observational data.

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