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Abstract Detail



Symbioses: Plant, Animal, and Microbe Interactions

Younginger, Brett [1], Ballhorn, Daniel [1].

A year in the life—a temporal examination of fungal endophyte communities in ferns.

Fungal endophytes are ubiquitous plant symbionts which may influence the evolutionary trajectory of their hosts. Despite recent awareness of endophyte diversity in angiosperms, we lack a basic understanding of the microbial communities that inhabit ferns. Ferns are not only the second largest group of vascular plants, but their unique ecology and manner of reproduction make them prime targets for investigations in endophyte community ecology. Additionally, within all host plant lineages, we lack an understanding of the temporal dynamics of endophyte communities over an entire growing season. This limits our ability to assess the inferences drawn in endophyte diversity studies conducted at a single point in time. To better understand the long-term temporal turnover of plant-associated endophyte communities, and to assess how early stages of symbiosis influence fungal community composition over time, we examined the initial colonization and monthly turnover of endophytes in the temperate fern, Polystichum munitum (western sword fern). Utilizing culture-independent techniques, we surveyed endophyte communities in a population of P. munitum at the Oregon Coast Range upon initial emergence of croziers in the spring, and every month thereafter for ten months. Our results demonstrate that endophytes colonize newly-emerged croziers in a patchy, heterogeneous manner with a high degree of turnover in the earliest months of the growing season. Priority effects do not play a substantial role in competitive outcomes in this study system since the earliest colonizers rapidly wane over the course of two months. In contrast, a later colonist—which is closely related to Articulospora tetracladia (Helotiaceae) at 97% sequence similarity—quickly outcompetes neighboring endophytes in the summer. The trend continues through the fall and winter months, where A. tetracladia comprises the most abundant taxon across plants; however, other taxa from the fungal family Pseudeurotiaceae are able to persist in the community despite the presence of this competitor. The study site is located in a dense understory of an established temperate forest with an abundance of fungal propagules that likely promote the colonization of fern hosts. If the host tissue is assumed to be relatively homogeneous across the study site, there appears to be a strong competition/colonization trade-off occurring, where A. tetracladia counteracts the effects of these dispersal events. This shift in community composition, favoring a single taxon, implies a greater importance of competition over dispersal in this endophyte system and demonstrates that endophyte turnover is highly dependent upon season and the presence of specific competitors.


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1 - Portland State University, Biology, 1719 SW 10th Ave, SRTC Rm 246, Portland, OR, 97201, USA

Keywords:
Community Ecology
Endophytes
Ferns
Temporal Turnover.

Presentation Type: Oral Paper
Number: 24007
Abstract ID:453
Candidate for Awards:None


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