In this post, Eric Griffin, Assistant Professor at New Mexico Highlands University, discusses his paper Plant host identity and soil macronutrients explain little variation in sapling endophyte community composition: Is disturbance an alternative explanation?, which was shortlisted for the 2019 Harper Prize. You can see a full list of all shortlisted papers in the Harper Prize 2019 Virtual Issue.
Our group sought to determine the degree to which host species drive leaf bacterial endophytes in leaves among five common trees in a tropical forest in Panama. Moreover, we simultaneously measured how important soil nutrient additions (using a 15-year N, P, K soil fertilization experiment) and disturbance (using commercial antibiotics) are in structuring bacterial endophyte community composition.
Counter to our expectations, we found little evidence to support our hypotheses that host identity and soil nutrients are important drivers of endophyte communities. In fact, a small portion of bacterial operational taxonomic units (OTUs) were present on almost all individuals of all tree species and made up almost a third of all total sequences, suggesting that a core microbiome exists among all focal tree species. Moreover, we found that disturbance (antibiotics) explained more endophyte variation than all nutrient addition combinations combined and twice the variation explained by host identity for all five tree species.
Overall, our findings are in stark contrast to studies of bacterial and fungal epiphytes (leaf surface), as well as insect herbivores, suggesting that the drivers of bacterial endophytes may be different compared to epiphytes and insects. In addition, our findings highlighting the importance of disturbance parallel the critical role of disturbance in other areas of ecology. In all, we provide one of the first empirical, rather than observational, studies which uses leaf endophytes to test prominent theories in community ecology.
Eric Griffin grew up outside of Atlanta, Georgia, and after graduating from Berry College completed his PhD at the University of Pittsburgh under the supervision of Walt Carson. Afterwards, he received a Smithsonian Environmental Research Center Postdoctoral Research Fellowship to work on the roles of microbes in mediating plant biodiversity–ecosystem function relationships with staff scientists John Parker and Melissa McCormick. After his second year, Eric received the Smithsonian’s Distinguished Postdoctoral Research Fellowship to continue this work for an additional year. In 2019, Eric began as an Assistant Professor at New Mexico Highlands University, where he currently continues his work on the identities and impacts of plant microbiomes.
You can read all of the Harper Prize 2019 shortlisted papers in our Virtual Issue.