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Plants harbor a variety of fungal symbionts both above- and belowground, yet little is known about how these fungi interact within hosts, especially in a world where resource availability is changing due to human activities. Systemic vertically transmitted endophytes such as Epichloë spp. may have particularly strong effects on the diversity and composition of later-colonizing symbionts such as root fungal endophytes, especially in primary successional systems. We made use of a long-term field experiment in Great Lakes sand dunes to test whether Epichloë colonization of the dune-building grass, Ammophila breviligulata, could alter fungal root endophyte species richness or community composition in host plants. We also tested whether nitrogen addition intensified the effects of Epichlöe on the root endophyte community. We found that Epichloë increased richness of root endophytes in Ammophila by 17% overall, but only shifted community composition of root endophytes under nitrogen-enriched conditions. These results indicate that Epichlöe acts as a key species within Ammophila, changing richness and composition of the root mycobiome and integrating above- and belowground mycobiome interactions. Further, effects of Epichloë on root endophyte communities were enhanced by N addition, indicating that this fungal species may become even more important in future environments.

Abstract The production of novel hybrid zones is an ecologically important consequence of globally increasing rates of species introductions and invasions. Interspecific hybridization can facilitate gene flow between parent species or produce novel taxa that may alter invasion dynamics or ecosystem services. The coastal sand dunes of the U.S. Pacific Northwest coast are densely populated by two non‐native, congeneric, dune‐building beachgrasses (Ammophila arenaria and A. breviligulata). Here, we present morphological, cytological, and genetic evidence that the two beachgrass species have hybridized in this globally unique range overlap. The A. arenaria × A. breviligulata hybrid has been found at 12 coastal sites in Washington and Oregon. It is a first‐generation hybrid between the beachgrass species as evidenced by genome size comparisons and single nucleotide polymorphism genotyping. It is intermediate between the parent grasses in many morphological characters but exceeds both parents in shoot height, a trait associated with dune‐building potential. Understanding the ecological and population genetic consequences of this novel hybridization event is of the utmost importance in a system where any change in dominant beachgrass species can have large effects on both biodiversity management and coastal protection.

An annotated list is given and the distribution of five species of digger wasps genus Ammophila, collected in the circumpolar regions of Western Siberia (in the Yamalo-Nenets Autonomous District) in 2017, is specified.

The grass Ammophila breviligulata (American beachgrass) is known to host an endophyte of the genus Epichloë. Based on morphological characteristics it was originally identified as Acremonium typhinum var. ammophilae and is currently designated as Epichloë typhina var. ammophilae. However, the Epichloë species has not previously been identified based on DNA sequence data. Based on phylogenetic placement of beta-tubulin and translation elongation factor 1-alpha DNA sequences the endophyte is identified as a member of E. amarillans rather than E. typhina.

Abstract Biological invasions are a threat to ecological communities and ecosystems, yet understanding the processes that mediate invasion and the environmental contexts in which these processes are important remains a challenge. In this study, we investigated how disturbance and biotic interactions with pathogens and microbial symbionts mediate invasion of American beachgrass (Ammophila breviligulata) in early‐ and late‐successional coastal dune habitats. First, we tested the effect of disturbance on biomasses of two exotic beachgrass species (the invading A. breviligulata and the established A. arenaria) and a native beachgrass (Elymus mollis) by growing plants with and without a disturbance manipulation in early‐ and late‐successional habitats. We quantified root colonization by fungal symbionts and infection by plant‐parasitic nematodes to determine the effect of potential mutualists and pathogens on plant biomass. Second, we tested whether soil microbes associated with the established A. arenaria mediated A. breviligulata invasion by inoculating potted plants with microbes from early‐ and late‐successional habitat. We found no effect of disturbance on biomass of the invading A. breviligulata or native E. mollis, whereas A. arenaria biomass increased when grown with disturbance. Colonization by arbuscular mycorrhizal fungi and by fungal endophytes were poor predictors of plant biomass, and plant‐parasitic nematodes were infrequently observed. Microbe addition increased belowground biomass of A. breviligulata, but not A. arenaria, compared to control treatments. Overall, our results suggest that A. breviligulata invasion in both the early‐ and late‐successional habitat is mediated by its lack of disturbance dependence and positive effects of soil microbes. These results have important implications for other primary successional systems and contribute to our understanding of how ecological contexts influence invasion processes.