Disentangling the ecological factors that contribute to the assembly of the microbial symbiont communities within eukaryotic hosts is an ongoing challenge. Broadly speaking, symbiont propagules arrive either from external sources in the environment or from internal sources within the same host individual. To understand the relative importance of these propagule sources to symbiont community assembly, we characterized symbiotic fungal endophyte communities within the roots of three species of beachgrass in a field experiment. We manipulated two aspects of the external environment, successional habitat and physical disturbance. To determine the role of internal sources of propagules for endophyte community assembly, we used beachgrass individuals with different pre-existing endophyte communities. Endophyte species richness and community composition were characterized using culture-based and next-generation sequencing approaches. Our results showed that external propagule sources associated with successional habitat, but not disturbance, were particularly important for colonization of most endophytic taxa. In contrast, internal propagule sources played a minor role for most endophytic taxa but were important for colonization by the dominant taxon Microdochium bolleyi. Our findings highlight the power of manipulative field experiments to link symbiont community assembly to its underlying ecological processes, and to ultimately improve predictions of symbiont community assembly across environments.
Bibliographical noteFunding Information:
University of Minnesota; US Environmental Protection Agency, Grant/Award Number: EPA/NCER R833836; National Science Foundation, Grant/Award Number: DEB 1045608), Graduate Research Fellowship Program, NSF 00039202; Puget Sound Mycological Society, Grant/Award Number: Ben Woo Fellowship; NSF Integrative Graduate Education and Research Traineeship Introduced Species and Genotypes program, (DGE-0653827)
- Illumina MiSeq
- community assembly
- culture-based sequencing
- priority effects