Mycorrhizal networks and coexistence in species‐rich orchid communities

Jacquemyn, Hans; Brys, Rein; Waud, Michael; Busschaert, Pieter; Lievens, Bart

doi:10.1111/nph.13281

Cited by 93 publications

(114 citation statements)

References 54 publications

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“…Members of the Thelephoraceae were also detected in the forest orchid Neottia ovata 1333. However, recent investigations of a large number of terrestrial orchids in Mediterranean grasslands showed that associations with ectomycorrhizal fungi are not restricted to woodland orchids and that grassland orchids may also commonly associate with members of the Thelephoraceae36. Our results are clearly in line with these observations and suggest that these fungi may play a role in the life cycle of grassland orchids as well.…”

Section: Discussionsupporting

confidence: 90%

Habitat-driven variation in mycorrhizal communities in the terrestrial orchid genus Dactylorhiza

Jacquemyn

Waud

Merckx

et al. 2016

Sci Rep

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Orchid species are critically dependent on mycorrhizal fungi for completion of their life cycle, particularly during the early stages of their development when nutritional resources are scarce. As such, orchid mycorrhizal fungi play an important role in the population dynamics, abundance, and spatial distribution of orchid species. However, less is known about the ecology and distribution of orchid mycorrhizal fungi. In this study, we used 454 amplicon pyrosequencing to investigate ecological and geographic variation in mycorrhizal associations in fourteen species of the orchid genus Dactylorhiza. More specifically, we tested the hypothesis that variation in orchid mycorrhizal communities resulted primarily from differences in habitat conditions where the species were growing. The results showed that all investigated Dactylorhiza species associated with a large number of fungal OTUs, the majority belonging to the Tulasnellaceae, Ceratobasidiaceae and Sebacinales. Mycorrhizal specificity was low, but significant variation in mycorrhizal community composition was observed between species inhabiting different ecological habitats. Although several fungi had a broad geographic distribution, Species Indicator Analysis revealed some fungi that were characteristic for specific habitats. Overall, these results indicate that orchid mycorrhizal fungi may have a broad geographic distribution, but that their occurrence is bounded by specific habitat conditions.

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Section: Discussionsupporting

confidence: 90%

Habitat-driven variation in mycorrhizal communities in the terrestrial orchid genus Dactylorhiza

Jacquemyn

Waud

Merckx

et al. 2016

Sci Rep

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“…2012; Jacquemyn et al. 2015). While mutualistic plant–pollinator networks generally display a nested structure, which minimizes interspecific competition and enhances diversity (Bastolla et al.…”

Section: Discussionmentioning

confidence: 99%

“…For example, Jacquemyn et al. (2015) observed a high degree of specialization and modularity between orchids and their associated orchid mycorrhizal fungi. By contrast, network analysis of arbuscular mycorrhizal (AM) fungal communities showed significant nestedness (Chagnon et al.…”

Section: Introductionmentioning

confidence: 99%

High richness of ectomycorrhizal fungi and low host specificity in a coastal sand dune ecosystem revealed by network analysis

Roy‐Bolduc

Laliberté

Hijri

2015

Ecology and Evolution

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Ectomycorrhizal (EM) fungi are ubiquitous in temperate and boreal forests, comprising over 20,000 species forming root symbiotic associations with Pinaceae and woody angiosperms. As much as 100 different EM fungal species can coexist and interact with the same tree species, forming complex multispecies networks in soils. The degree of host specificity and structural properties of these interaction networks (e.g., nestedness and modularity) may influence plant and fungal community assembly and species coexistence, yet their structure has been little studied in northern coniferous forests, where trees depend on EM fungi for nutrient acquisition. We used high‐throughput sequencing to characterize the composition and diversity of bulk soil and root‐associated fungal communities in four co‐occurring Pinaceae in a relic foredune plain located at Îles de la Madeleine, Québec, Canada. We found high EM fungal richness across the four hosts, with a total of 200 EM operational taxonomic units (OTUs), mainly belonging to the Agaricomycetes. Network analysis revealed an antinested pattern in both bulk soil and roots EM fungal communities. However, there was no detectable modularity (i.e., subgroups of interacting species) in the interaction networks, indicating a low level of specificity in these EM associations. In addition, there were no differences in EM fungal OTU richness or community structure among the four tree species. Limited shared resources and competitive exclusion typically restrict the number of taxa coexisting within the same niche. As such, our finding of high EM fungal richness and low host specificity highlights the need for further studies to determine the mechanisms enabling such a large number of EM fungal species to coexist locally on the same hosts.

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“…Using species delineation based on 3% ITS divergence is unlikely to have masked cryptic Tulasnellaceae species: first, this is a usual threshold and ITS species delineation is validated in Tulasnellaceae by the fact that it is congruent with other genes (Linde, Phillips, Crisp, & Peakall, 2014); second, lowering the threshold to 1.5% did not change OTU delineation in our work. This fungus family is common in several Ophrys species (Jacquemyn, Brys, Waud, Busschaert, & Lievens, 2015; Pecoraro, Girlanda, Liu, Huang, & Perotto, 2015). Only a small difference in mycorrhizal partners was found earlier in closely related species of the genus Orchis in sympatry (Jacquemyn et al., 2011), and sexually deceptive orchids of the genus Chiloglottis were shown to share a narrow taxonomic group of Tulasnella fungi (Roche et al., 2010).…”

Section: Discussionmentioning

confidence: 99%

Floral scent and species divergence in a pair of sexually deceptive orchids

Gervasi

Selosse

Sauve

et al. 2017

Ecology and Evolution

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Speciation is typically accompanied by the formation of isolation barriers between lineages. Commonly, reproductive barriers are separated into pre‐ and post‐zygotic mechanisms that can evolve with different speed. In this study, we measured the strength of different reproductive barriers in two closely related, sympatric orchids of the Ophrys insectifera group, namely Ophrys insectifera and Ophrys aymoninii to infer possible mechanisms of speciation. We quantified pre‐ and post‐pollination barriers through observation of pollen flow, by performing artificial inter‐ and intraspecific crosses and analyzing scent bouquets. Additionally, we investigated differences in mycorrhizal fungi as a potential extrinsic factor of post‐zygotic isolation. Our results show that floral isolation mediated by the attraction of different pollinators acts apparently as the sole reproductive barrier between the two orchid species, with later‐acting intrinsic barriers seemingly absent. Also, the two orchids share most of their fungal mycorrhizal partners in sympatry, suggesting little or no importance of mycorrhizal symbiosis in reproductive isolation. Key traits underlying floral isolation were two alkenes and wax ester, present predominantly in the floral scent of O. aymoninii. These compounds, when applied to flowers of O. insectifera, triggered attraction and a copulation attempt of the bee pollinator of O. aymoninii and thus led to the (partial) breakdown of floral isolation. Based on our results, we suggest that adaptation to different pollinators, mediated by floral scent, underlies species isolation in this plant group. Pollinator switches may be promoted by low pollination success of individuals in dense patches of plants, an assumption that we also confirmed in our study.

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Mycorrhizal networks and coexistence in species‐rich orchid communities

Cited by 93 publications

References 54 publications

Habitat-driven variation in mycorrhizal communities in the terrestrial orchid genus Dactylorhiza

Habitat-driven variation in mycorrhizal communities in the terrestrial orchid genus Dactylorhiza

High richness of ectomycorrhizal fungi and low host specificity in a coastal sand dune ecosystem revealed by network analysis

Floral scent and species divergence in a pair of sexually deceptive orchids

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