Research
The ecology and evolution of cooperative communities
Living organisms interact with a remarkable diversity of partner species simultaneously and sequentially in nature. Plants, for example are host to diverse communities of bacteria, archaea, fungi, protists and more (the microbiome) in addition to their many macroscopic, above-ground mutualisms with pollinators, seed dispersers, and biotic defenders. These shared partners have the capacity to alter host outcomes non-additively through direct interactions (e.g. antagonism or facilitation), as well physiological trade-offs and genetic links among host reward traits expression.
The community ecology of microbiomes
The diverse microbiomes of eukaryotic organisms provide a range of host benefits from pathogen suppression to the provisioning of key, often limiting resources, to increasing host tolerance to abiotic and biotic stressors. Unlike pairwise mutualisms, however, host-associated microbiomes are not singular entities, but vast communities of microorganisms that interact with one another through familiar dynamics of competition, exploitation, and cooperation.
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My research investigates the consequences of these community interactions through large, high-throughput experiments and community sequencing approaches. Working with the common duckweed Lemna minor, I have shown that mutualistic microbiomes can emerge from internal interactions among largely neutral microbes, and that variation in community composition can have important affects on key host phenotypes and fitness. I am now employing rapid, miniaturized experiments with the single-celled green alga Chlamydomonas reinhardtii and its phycosphere microbes to investigate the importance of emergent community effects on host growth rate and tolerance of environmental stressors.
Evolutionary constraints in multipartite mutualisms
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Genetically correlations between reward traits associated with multiple mutualisms (either through pleiotropy or linkage disequilibrium), can either constrain or facilitate the multivariate evolution of host traits, depending on whether the multivariate axes of genetic variation are aligned with those of selection. Bridging community ecology and micro-evolutionary processes, my research has shown that genetic correlations among plant reward traits in Turnera ulmifolia's tripartite plant-ant-pollinator mutualisms bind together the evolutionary fates of these interactions. These genetic links may help explain the maintenance of plant-ant-pollinator interactions, given widespread evidence of ant antagonism towards plant pollinators.
The effects of mutualism on stress tolerance and niche expansion
Mutualisms can enable species' persistence under otherwise unsustainable conditions by improving their access to limiting resources or buffering their responses to stressors like heat, drought, and salinization. Working across diverse systems, my work demonstrates the fundamental importance of accounting for cooperative interactions when assessing species' niche breadths and stress responses.
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My research has shown that plant-microbiome interactions in duckweeds can improve plant tolerance of urban stressors like salt and road run-off, with differences in the efficacy of microbiome communities correlated with their position on an urban to rural gradient. In further work, I experimentally evolved simplified Lemna minor microbiomes under salt stress, revealing that ecological and evolutionary changes in the duckweed microbiome can improve host performance under benign and stressful conditions. In ongoing research efforts, I am harnessing Chlamydomonas and its phycosphere microbes to understand how host-associated microbes can affect key ecological traits like thermal niche breadth (Thermal Performance Curves), salt tolerance, and minimum resource requirements (R*).
Evolutionary constraints and ecological limits
My work exists at the intersection of ecology and evolution, elucidating the feedbacks between multivariate trait evolution and the complex, often conflicting ecological organisms face. I use quantitative genetic tools and Bayesian methods to fit genetic variance-covariance (G) matrices to plant traits that govern multiple mutualism, highlighting the importance of genetic correlations among mating system variation and pollination and defence mutalisms in plants. I frequently employ experimental evolution in my research, working in high-throughput lab systems like duckweeds to show that microbiome evolution can increase host tolerance of salt stress. I also employ computational approaches, fitting ecological models using Bayesian approaches to investigate the existence of hard evolutionary limits (Pareto fronts) on niche breadth parameters (TPC, R*) in experimentally evolved Chlamydomonas populations.​​
