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Summary Coinvasive ectomycorrhizal (ECM) fungi allow Pinaceae species to invade regions otherwise lacking compatible symbionts, but ECM fungal communities permitting Pinaceae invasions are poorly understood. In the context of Pinaceae invasions on Isla Victoria, Nahuel Huapi National Park, Argentina, we asked: what ECM fungi are coinvading with Pinaceae hosts on Isla Victoria; are some ECM fungal species or genera more prone to invade than others; and are all ECM fungal species that associate with Northern Hemisphere hosts also nonnative, or are some native fungi compatible with nonnative plants? We sampled ECMs from 226 Pinaceae host plant individuals, both planted individuals and recruits, growing inside and invading from plantations. We used molecular techniques to examine ECM fungal communities associating with these trees. A distinctive subset of the ECM fungal community predominated far from plantations, indicating differences between highly invasive and less invasive ECM fungi. Some fungal invaders reported here have been detected in other locations around the world, suggesting strong invasion potential. Fungi that were frequently detected far from plantations are often found in early-successional sites in the native range, while fungi identified as late-successional species in the native range are rarely found far from plantations, suggesting a means for predicting potential fungal coinvaders.

Ectomycorrhizal plants and fungi are ubiquitous in mainland forests, but because of dispersal limitations are predicted to be less common on isolated islands. For instance, no native ectomycorrhizal plants or fungi have ever been reported from Hawaii, one of the most remote archipelagos on Earth. Members of the plant tribe Pisonieae are common on many islands, and prior evidence shows that some species associate with ectomycorrhizal fungi. However, until now, the Pisonieae species of Hawaii had yet to be examined for their mycorrhizal status. Here we sampled roots from members of the genus Pisonia growing on the Hawaiian islands of Oahu, Maui and Hawaii. We used molecular and microscopic techniques to categorize trees with respect to their mycorrhizal associations. We report that the Hawaiian endemic Pisonia sandwicensis forms ectomycorrhizas with at least five fungal operational taxonomic units (corresponding closely to species) belonging to four genera. We also report that this tree species is monophyletic with other ectomycorrhizal Pisonia species. We suggest that in light of the newly discovered Hawaiian ectomycorrhizal fungal community and other island ectomycorrhizal communities, dispersal limitations do not prevent the colonization of remote islands by at least some ectomycorrhizal fungi.

Like all obligately ectomycorrhizal plants, pines require ectomycorrhizal fungal symbionts to complete their life cycle. Pines introduced into regions far from their native range are typically incompatible with local ectomycorrhizal fungi, and, when they invade, coinvade with fungi from their native range. While the identities and distributions of coinvasive fungal symbionts of pine invasions are poorly known, communities that have been studied are notably depauperate. However, it is not yet clear whether any number of fungal coinvaders is able to support a Pinaceae invasion, or whether very depauperate communities are unable to invade. Here, we ask whether there is evidence for a minimum species richness of fungal symbionts necessary to support a pine/ectomycorrhizal fungus coinvasion. We sampled a Pinus contorta invasion front near Coyhaique, Chile, using molecular barcoding to identify ectomycorrhizal fungi. We report that the site has a total richness of four species, and that many invasive trees appear to be supported by only a single ectomycorrhizal fungus, Suillus luteus. We conclude that a single ectomycorrhizal (ECM) fungus can suffice to enable a pine invasion. Fil: Hayward, Jeremy. State University Of New York; Estados Unidos Fil: Horton, Thomas R.. State University Of New York; Estados Unidos Fil: Pauchard, Aníbal. Universidad de Concepción; Chile. Universidad de Chile; Chile Fil: Nuñez, Martin Andres. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; Argentina

Alpova diplophloeus (Boletales, Paxillaceae) is the only currently recognized Alpova in North America with a brownish peridium, large gleba chambers and which forms ectomycorrhizas with Alnus. However, A. diplophloeus as currently circumscribed is a polyphyletic species, with at least three distinct genetic entities. Using a combination of molecular and morphological characters, we examined the type collections of A. diplophloeus, as well as species synonymized with it, including A. cinnamomeus and Rhizopogon parvisporus. We also examined several other collections of A. diplophloeus complex basidiomata. We describe A. diplophloeus sensu stricto; we also resurrect A. cinnamomeus, synonymized with R. parvisporus and describe a new species, A. concolor, from the complex.

Biological invasions are often complex phenomena because many factors influence their outcome. One key aspect is how non-natives interact with the local biota. Interaction with local species may be especially important for exotic species that require an obligatory mutualist, such as Pinaceae species that need ectomycorrhizal (EM) fungi. EM fungi and seeds of Pinaceae disperse independently, so they may use different vectors. We studied the role of exotic mammals as dispersal agents of EM fungi on Isla Victoria, Argentina, where many Pinaceae species have been introduced. Only a few of these tree species have become invasive, and they are found in high densities only near plantations, partly because these Pinaceae trees lack proper EM fungi when their seeds land far from plantations. Native mammals (a dwarf deer and rodents) are rare around plantations and do not appear to play a role in these invasions. With greenhouse experiments using animal feces as inoculum, plus observational and molecular studies, we found that wild boar and deer, both non-native, are dispersing EM fungi. Approximately 30% of the Pinaceae seedlings growing with feces of wild boar and 15% of the seedlings growing with deer feces were colonized by non-native EM fungi. Seedlings growing in control pots were not colonized by EM fungi. We found a low diversity of fungi colonizing the seedlings, with the hypogeous Rhizopogon as the most abundant genus. Wild boar, a recent introduction to the island, appear to be the main animal dispersing the fungi and may be playing a key role in facilitating the invasion of pine trees and even triggering their spread. These results show that interactions among non-natives help explain pine invasions in our study area. Fil: Nuñez, Martin Andres. University Of Tennessee; Estados Unidos; . Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; Argentina Fil: Hayward, Jeremy. State University Of New York; Estados Unidos Fil: Horton, Thomas R.. State University Of New York; Estados Unidos Fil: Amico, Guillermo Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; Argentina Fil: Dimarco, Romina Daniela. University Of Tennessee; Estados Unidos; Fil: Barrios Garcia, M. Noelia. University Of Tennessee; Estados Unidos Fil: Simberloff, Daniel. University Of Tennessee; Estados Unidos