University of Miami Coral Gable, Florida, United States
Background/Question/Methods Habitat fragmentation – the breaking up of natural landscapes – is a pervasive threat to biodiversity worldwide, not only affecting individual organisms, but also impacting interspecific interactions that shape the remaining communities. These impacts to species interactions can happen to changes to the remaining habitat patches (e.g., environmental filtering) and their connectivity (e.g., dispersal limitation). An important aspect of anthropogenic fragmentation is the introduction of a novel “matrix” habitat(s), which can influence dispersal of organisms through these landscapes. Specifically, matrix-driven decreases to habitat connectivity can impede dispersal of beneficial partners between fragments. Despite the growing body of research investigating the effects of fragmentation on mutualistic interactions, we have very limited knowledge of how habitat fragmentation affects plant microbiomes, which are known to be crucial to plant health and functioning. Using field collections, microbiome sequencing, and greenhouse experiment in the imperiled Pine Rocklands ecosystem, we (1) investigated which fragmentation metrics explained microbial diversity and composition within fragments as well as between native and adjacent urban habitat, (2) identified fragmentation-responding microbial taxa that affected individual plant performance and allocation, and (3) tested whether urbanization-driven changes in microbiomes affected plant community productivity and composition.
Results/Conclusions Microbial diversity and composition significantly differed between native habitat and urban matrix, with symbiotrophs increasing ~80% and pathotrophs decreasing >300% in native habitats. Further, fragmentation metrics explained variation in microbial diversity of native fragments but not the adjacent urban matrix. These results indicate that both dispersal limitation and environmental filtering are likely playing important roles in structuring native microbiomes in these landscapes. Importantly, fragmentation-associated changes to microbiomes affected individual plant performance and community productivity. We found ten fungal and six bacterial families that responded to fragmentation were also associated with differences in plant growth/allocation, suggesting dispersal limitation is likely a key component in determining what microbial partners plants can associate with. Native habitat microbiomes increased overall plant community productivity by ~300%, while urban microbiomes did not affect productivity, indicating that native plant communities showed diminished reliance on urban microbiomes. Our study documented changes in microbial diversity/composition across the landscape and also demonstrated that fragmentation-responding microbial taxa are important for plant performance and native microbiomes persisting in fragmented landscapes are imperative to plant community productivity. We are currently investigating the differences between airborne and soil microbiomes across this fragmented landscape to better understand how these microbiomes are moving throughout the habitat.