Tuesday, August 7, 2018: 2:30 PM
239, New Orleans Ernest N. Morial Convention Center
Marion Donald1, Adam S. Hadley2, Manpreet K. Dhami3, Kara Leimberger2, Po-Ju Ke4, Tadashi Fukami5 and Thomas Miller6, (1)BioSciences, Rice University, Houston, TX, (2)Forest Ecosystems & Society, Oregon State University, Corvallis, OR, (3)Biodiversity and Conservation, Landcare Research, Lincoln, New Zealand, (4)Department of Biology, Stanford University, Stanford, CA, (5)Biology, Stanford University, Stanford, CA, (6)Department of BioSciences, Rice University, Houston, TX
Background/Question/Methods Habitat loss is a major contributor to species extinction and biodiversity loss worldwide. Understanding how habitat loss effects communities is crucial for biodiversity conservation. Many types of communities are distributed across a patchy landscape of heterogeneous habitat patches and are connected via the exchange of immigrants and emigrants, thereby creating a metacommunity. Theoretical work has revealed the consequences of loss of specific habitat types for metacommunity biodiversity, yet empirical tests remain few. In a large-scale empirical study of a Neotropical floral nectar microbial metacommunity, we tested the effects of floral patch loss on nectar microbial metacommunity diversity. Floral nectar hosts microbial communities that are vectored amongst the nectar of co-flowering plant species by pollinators. Floral species may constitute heterogeneous patches in the metacommunity based on physical properties or their role in maintaining dispersal. We addressed the effects of floral host loss on microbial metacommunitiy diversity. We hypothesized that if the floral species hosts a unique microbial community and is critical for sustaining microbial dispersal via pollinators, then the removal of this floral patch would result in a decrease in local (alpha) and regional (gamma) diversity, and an increase in the variation between communities (beta diversity).
Specifically, Heliconia tortuosa, a common understory shrub considered crucial for sustaining hummingbird communities during the dry-season, was removed from small forest fragments. We captured hummingbirds in these forest sites and ones in which H. tortuosa was present to determine the effects of floral patch type loss on microbial dispersal vectors. We used 16S DNA metabarcoding to characterize the bacterial floral nectar communities found within these forest sites.
Results/Conclusions
We found that H. tortuosa did not host a unique bacterial community, despite having high nectar volume and high sucrose concentration. Hummingbird abundance was reduced following the removal of H. tortuosa. Beta diversity of the nectar microbial communities was unaffected. However, several bacteria OTUs (corresponding to Acinetobacter, Pantoea, Pseudomonas, Herbaspirillum, and Neorhizobium) were found in significantly decreased abundances in floral nectar from sites in which H. tortuosa was removed. Acinetobacter, Pseudomonas, and Pantoea are commonly found in floral nectar and their decrease may be due to the parallel decreased hummingbird abundance or shifts in pollinator community composition and visitation. These changes may reduce dispersal or increase the prevalence of fungal nectar microbes, which can preclude bacteria through priority effects. This work is important for understanding the cascading effects of habitat loss within metacommunities.
