Ecology and evolution of plant-animal and host-microbe mutualisms

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My research team studies the ecology and evolution of mutualism. Most animals and plants are involved in at least one mutualism; they depend on other species for nutrition, protection, or dispersal in interactions that feed back to benefit to their partners. Well-known examples of mutualism include pollination, seed dispersal, and ant-plant symbioses, but the fastest growing area of mutualism research is the host-associated microbiome, a term that refers either to all the microbes living together in or on a host, or their collective genomes. Many microbes in these communities are beneficial to hosts, or at least not pathogenic, but there are many open questions about how microbiomes affect host physiology, ecology, and evolution. My research program seeks to understand how mutualism links the fates of interacting species, affecting their distribution and abundance, trait and molecular evolution, and even the diversification of life on Earth. This grant addresses four fundamental questions about mutualism ecology and evolution in diverse plant-animal and host-microbe systems: 1) How does mutualism evolve at a genomic level? Studying ant-plant and legume-rhizobium mutualisms, we will explore mutualism's molecular basis and use approaches from evolutionary genomics to infer how selection acts on genes that encode mutualistic traits. 2) How do multiple mutualisms evolve at micro- and macro-evolutionary scales? We will test whether pollinators and ant mutualists exert non-additive selection on a tropical plant in field common garden and assemble a global dataset of multiple plant-animal and plant-microbe mutualisms to explore how they evolve in tandem across the plant phylogeny. 3) Can we predict host benefits across microbiomes and environments? We are developing a high-throughput experimental system using the tiny aquatic plant Lemna minor and its microbiota, and we will test the outcome of host-microbe interactions across many distinct microbial communities and in many multivariate environments. 4) Which 'second genome' has more persistent transgenerational effects: the microbiome or the epigenome? We will use our new system from 3) to grow host populations in stressful and benign environments and experimentally manipulate microbiota and epigenetic marks, measuring host phenotypes and fitness across generations. We will determine the relative importance of the microbiome and the epigenome to transgenerational plasticity, especially in response to stress. This research will significantly improve our understanding of how mutualisms evolve through studies of real-world systems with high ecological or genomic complexity. It will also provide broad training to HQP who will learn to conduct rigorous lab and field experiments and acquire in-demand skills in molecular and computational biology. This integrative approach encourages the intellectual development of HQP and will prepare them for careers in basic or applied science.