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Abstract：
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.
摘要：
解开有助于真核宿主内微生物共生体群落组装的生态因子是一个持续的挑战。广义地说,共生体繁殖体来自环境中的外部来源或来自同一宿主个体中的内部来源。要了解这些传播源对共生生物群落组装的相对重要性，在田间试验中，我们对三种海滩草的根内共生真菌内生菌群落进行了表征。我们操纵了外部环境的两个方面，演替性栖息地和物理干扰。为了确定繁殖体内部来源对内生菌群落组装的作用，我们使用了具有不同预先存在的内生菌群落的海滩草个体。使用基于培养和下一代测序方法来表征内生菌物种丰富度和群落组成。我们的结果表明，与演替栖息地相关的外部繁殖源，但不是干扰，对于大多数内生植物分类群的定殖特别重要。相比之下,内部繁殖源在大多数内生类群中起着次要作用，但对于优势类群Microdochiumbolleyi的定殖很重要。我们的发现强调了操纵性野外实验将共生体群落组装与其潜在的生态过程联系起来的力量，并最终改善跨环境的共生体社区组装的预测。
