Research in the laboratory focuses on the ecological and evolutionary consequences of interactions among species, including mutualism, parasitism, and competition. We use theory, lab and field experiments, and synthetic approaches to address research questions. Our empirical work focuses mostly on interactions between trees and diverse communities of symbiotic ectomycorrhizal fungi. You can find a list of our publications here.
Ongoing projects fall into two general categories:
Local ecology of species interactions and communities. These projects aim to understand the strength, mechanisms, and community-level consequences of interactions between species in plant and mycorrhizal fungal communities. Current projects and major foci include:
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How do mycorrhizal fungi influence plant-plant interactions? As part of an ongoing collaboration with Michael Booth (University of Alaska Fairbanks, Principia College, and frequent visiting researcher in our lab), we are investigating how belowground mycorrhizal networks between trees influence the strength of plant-plant interactions in forests. Results from a three-year field experiment show that access to mycorrhizal networks substantially enhanced survival of Monterey pine (Pinus radiata) seedlings in coastal California (Booth and Hoeksema, In Press), and graduate student Kris Hennnig is following up on these results in his Master's thesis research. The broader goal of this project is to understand the consequences for plant community dynamics of variation in traits and functions of different mycorrhizal fungal taxa. -
How do biotic and abiotic factors interact to influence community assembly? A variety of different approaches are being used to address this question. Recently departed post-doc (and ongoing collaborator) Justine Karst is using meta-analysis (e.g., Karst et al. 2008), experiments, and analyses of observational datasets on ectomycorrhizal community structure, including a collaboration with Kitty Gehring at Northern Arizona University. Graduate student Anjel Craig is testing the impact of forest restoration treatments on the community structure of ectomycorrhizal fungi in the diverse upland forests of northern Mississippi. A collaboration with more than 15 different investigators (co-led with Nancy Johnson at Northern Arizona University and James Umbanhowar at the University of North Carolina), which started as a working group at the National Center for Ecological Analysis and Synthesis (NCEAS), aims to synthesize theory and empirical research on plant-mycorrhizal interactions to understand how their outcomes vary in response to changing biotic and abiotic contexts (Johnson et al. 2006, Schwartz et al. 2006). One product of this collaboration is the MycoDB database, in which we have compiled the results of hundreds of experiments in which plants were inoculated with mycorrhizal fungi. The database is being used in a series of meta-analyses (Hoeksema et al., manuscript in review), with the goal of better predicting the context-dependency of ecological outcomes in the mycorrhizal symbiosis.
- Do symbioses act like biological markets? We are using theory to generate explicit hypotheses regarding the relative importance of market forces in the dynamics and stability of potential mutualisms between host and symbiont species (e.g., Hoeksema & Schwartz 2003), including an ongoing collaboration with James Umbanhowar (University of North Carolina).
Mycorrhizal networking cylinder used in field experiments to estimate effects of mycorrhizal networks on plant-plant interactions
Example of graphical analysis of potential for benefit from resource-exchange mutualism using the comparative advantage market model
Evolution of species interactions and communities. These projects aim to understand the mechanisms and consequences of the evolution of species in response to each other and to their abiotic environment. Current projects include:
- What are the patterns and consequences of coevolution in diverse, widespread mutualisms? In collaboration with John Thompson (University of California, Santa Cruz), Deborah Rogers (University of California, Davis), and Jesus Vargas Hernandez (Colegio de Postgraduados, Mexico), we are examining genetic variability and patterns of local adaptation among the different species of ectomycorrhizal fungi associated with pines on the West Coast of North America (Hoeksema & Thompson 2007, Piculell et al. 2008, Hoeksema et al. 2009), including an ongoing project focusing on Monterey pine (Pinus radiata) in its native populations in California and Mexico.
- How do genetic correlations among complex traits influence coevolutionary adaptation? In collaboration with a diverse group of investigators including Dana Nelson (USDA Southern Institute of Forest Genetics), David Neale (University of California, Davis), and John Davis (University of Florida), we are using the interaction between loblolly pine (Pinus taeda) and its ectomycorrhizal fungi to understand how genetic correlations among plant traits, including coevolved community phenotypes, may constrain coevolution between plants and their mutualistic and parasitic symbionts. Graduate student Bridget Piculell is conducting the initial phase of this work using a common garden experiment with loblolly pine clones in southern Mississippi.
Expedition to Cedros Island, Mexico to collect seeds and soil (containing resistant propagules of ectomycorrhizal fungi) from native Monterey pine (Pinus radiata) forest.
Dana Nelson in a common garden of loblolly pine (Pinus taeda) clones near the USDA Southern Institute of Forest Genetics in Saucier, Mississippi.