Consumer‐resource interactions are often influenced by other species in the community, such as when neighbouring plants increase or reduce herbivory to a focal plant species (known as associational effects). The many studies on associational effects between a focal plant and some neighbour have shown that these effects can vary greatly in strength and direction. But because almost all of these studies measure associational effects from only one or two neighbour species, we know little about the actual range of associational effects that a plant species might encounter in a natural setting. This makes it difficult to determine how important effects of neighbours are in real field settings, and how associational effects might interact with competition and other processes to influence plant community composition. In this study, we used a field experiment with a focal species, We found that some neighbour species affected We found some evidence that a neighbour's associational effect was related to its biomass and phylogenetic proximity to the focal species. While neighbour species differed in their effects on physical leaf traits of focal plants (trichome density, specific leaf area, and leaf toughness), these traits did not appear to mediate the effects of neighbours on focal plant herbivory.
Closely related species are expected to have similar functional traits due to shared ancestry and phylogenetic inertia. However, few tests of this hypothesis are available for plant‐associated fungal symbionts. Fungal leaf endophytes occur in all land plants and can protect their host plant from disease by a variety of mechanisms, including by parasitizing pathogens (e.g., mycoparasitism). Here, we tested whether phylogenetic relatedness among species of
- PAR ID:
- 10446539
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Molecular Ecology
- Volume:
- 31
- Issue:
- 10
- ISSN:
- 0962-1083
- Page Range / eLocation ID:
- p. 3018-3030
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Understanding the origins and maintenance of host specificity, or why horizontally‐acquired symbionts associate with some hosts but not others, remains elusive. In this study, we explored whether patterns of host specificity in foliar fungal endophytes, a guild of highly diverse fungi that occur within the photosynthetic tissues of all major plant lineages, were related to characteristics of the plant community. We comprehensively sampled all plant host species within a single community and tested the relationship between plant abundance or plant evolutionary relatedness and metrics of endophyte host specificity. We quantified host specificity with methods that considered the total endophyte community per plant host (i.e., multivariate methods) along with species‐based methods (i.e., univariate metrics) that considered host specificity from the perspective of each endophyte. Univariate host specificity metrics quantified plant alpha‐diversity (structural specificity), plant beta‐diversity (beta‐specificity), and plant phylogenetic diversity (phylogenetic specificity) per endophyte. We standardized the effect sizes of univariate host specificity metrics to randomized distributions to avoid spurious correlations between host specificity metrics and endophyte abundance. We found that more abundant plant species harbored endophytes that occupied fewer plant species (higher structural specificity) and were consistently found in the same plant species across the landscape (higher beta‐specificity). There was no relationship between plant phylogenetic distance and endophyte community dissimilarity. We still found that endophyte community composition significantly varied among plant species, families, and major groups, supporting a plant identity effect. In particular, endophytes in angiosperm lineages associated with narrower phylogenetic breadths of plants (higher phylogenetic specificity) compared to endophytes within conifer and fern lineages. Overall, an effect of plant species abundance may help explain why horizontally‐transmitted endophytes vary geographically within host species ranges.
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Summary Foliar fungal endophytes are one of the most diverse guilds of symbiotic fungi found in the photosynthetic tissues of every plant lineage, but it is unclear how plant environments and leaf resource availability shape their diversity.
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