Mycorrhizal fungi affect orchid distribution and population dynamics

McCormick, Melissa; Whigham, Dennis F.; Canchani‐Viruet, Armando

doi:10.1111/nph.15223

Cited by 125 publications

(117 citation statements)

References 103 publications

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“…Because most orchids associate with only a narrow range of orchid mycorrhizal fungi (OMF), it is intuitive that OMF specificity should promote orchid rarity and limit orchid colonisation of islands. However, investigations into the effects of OMF specificity on orchid rarity and distributions have produced contrasting results (see review by Dearnaley, ), and whether orchids that associate with specific OMF strains are more limited in their distributions relative to orchids that associate with a wider range of OMF is still poorly understood (but see McCormick et al ., ).…”

Section: Functional Disharmonymentioning

confidence: 97%

Island disharmony revisited using orchids as a model group

et al. 2019

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Summary One central concept in island biology is that island assemblages form subsets of the mainland species pool, being disproportionately rich or poor in certain taxonomic groups. This unbalanced composition, termed ‘disharmony’, is generally explained using a taxon‐centred approach, linking the over‐ or under‐representation of taxa to their colonisation abilities. However, islands may also harbour ‘functionally’ disharmonic flora, being disproportionately rich or poor in species with certain traits, which may offer greater insights into the processes driving island colonisation. Here, we use orchids as a model to illustrate key processes involved in the formation of functionally disharmonic island floras, including filtering effects (for example biotic interactions), and speciation. Our synthesis is based on a comprehensive orchid dataset of 27 637 species and combines both a literature review and simple exploratory analyses to show that orchids are significantly under‐represented on islands relative to mainland regions and that insular orchids display shifts in functional traits, from the shortening of nectar spurs to facilitate ornithophily to changes in colour associated with generalist insect pollinators. We highlight that taxa are simply coarse proxies and that we need to consider species traits and interactions to gain a full understanding of the processes constraining plant assembly on islands.

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Section: Functional Disharmonymentioning

confidence: 97%

Island disharmony revisited using orchids as a model group

et al. 2019

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“…Although mycorrhizal dependency has been increasingly recognized as an important factor influencing both the distribution and abundance of orchid populations (McCormick & Jacquemyn, 2014;McCormick, Whigham, & Canchani-Viruet, 2018), at present little is known about the geographical distribution of orchid mycorrhizal fungi (OMF; reviewed in Jacquemyn, Duffy, et al, 2017). However, the widespread occurrence of orchids across the globe and in diverse ecosystems (Givnish et al, 2016) suggests that the OMF that are necessary for germination and seedling establishment are also widespread and not necessarily restricted to geographical regions.…”

Section: Introductionmentioning

confidence: 99%

Similarity in mycorrhizal communities associating with two widespread terrestrial orchids decays with distance

Xing

Gao

Zhao

et al. 2019

Journal of Biogeography

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Aim Interactions with mycorrhizal fungi are increasingly recognized as an important factor underlying the distribution and abundance of orchid species. However, the geographical distribution of orchid mycorrhizal fungi (OMF) and how their communities vary over large geographical areas are less well understood. Because climatic and environmental similarity may decrease with geographical distance or because some OMF have limited dispersal capabilities, similarities in orchid mycorrhizal communities can be expected to decrease with increasing distances separating orchid populations. However, up till now empirical evidence is largely lacking. Location Eurasia. Taxa Gymnadenia conopsea (L.) R. Brown and Epipactis helleborine (L.) Crantz. Methods High‐throughput sequencing was used to perform a cross‐continental comparison of OMF that associate with two widespread Eurasian terrestrial orchids, Epipactis helleborine and Gymnadenia conopsea. Both phylogenetic and nonphylogenetic measures of community dissimilarity and their components were calculated and related to geographical distances using Mantel tests. Results Our results showed that in both orchid species similarity in mycorrhizal communities decreased significantly with geographical distance. Decomposing the contribution of spatial turnover and nestedness to overall dissimilarity showed that the observed dissimilarity was mainly the result of species replacement between regions, and not of species loss. Similarly, a strong relationship was observed between phylogenetic community dissimilarity and geographical distance. Decomposing PCD values into a nonphylogenetic and phylogenetic component showed that orchid populations located closely next to each other were likely to contain the same operational taxonomic units (OTUs), but that the non‐shared taxa came from different phylogenetic clades. Species indicator analyses showed that the majority of OMF OTUs were restricted to particular geographical areas. However, some OTUs occurred in both continents, indicating that some fungi have very wide distributions. Main conclusions Overall, these results demonstrate that orchid mycorrhizal communities differ substantially across large geographical areas, but that the distribution of orchids is not necessarily restricted by the distribution of particular OMF. Hence, widespread orchid species can be considered mycorrhizal generalists that are flexible in the OMF with which they associate across large geographical areas.

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“…More research is needed on tropical orchid species to fully understand the symbioses between the host plant and the orchid mycorrhizal fungi and other root endophytes [52]. My results illuminate two more research agendas that would benefit from the inclusion of more tropical orchid species.…”

Section: Discussionmentioning

confidence: 76%

Host Tree Identity Influences Leaf Nutrient Relations of the Epiphyte Dendrobium guamense Ames.

Marler

2018

Horticulturae

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Epiphytic orchid species grow in stressful conditions that include nutrient deficiency. A greater understanding of the factors that influence epiphytic orchid nutrition may benefit conservationists and horticulturists. Green and senesced leaf nutrient concentrations of the epiphytic Dendrobium guamense were quantified among six host tree species to more fully understand the role of contrasting host identity. Green leaves for D. guamense plants on species with vertical stems contained greater nitrogen, calcium, iron, manganese, zinc, and boron concentrations. Green leaves for D. guamense plants on species with horizontal stems contained greater phosphorus, magnesium, and copper concentrations. Senesced D. guamense leaves followed similar patterns among the host species for all elements except calcium, manganese, and boron. The stoichiometry among green leaf macronutrients indicated nitrogen was most limiting, and the limitation was more severe for plants on horizontal stems. Carbon:nitrogen of senesced leaves indicated D. guamense plants on vertical stems produced higher quality leaf litter, predicting slower decomposition of orchid leaf litter from plants growing on hosts with horizontal stems. The results may improve horticultural decisions to support conservation efforts and show that host identity is a variable that should be more fully studied to understand epiphyte biology.

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Mycorrhizal fungi affect orchid distribution and population dynamics

Cited by 125 publications

References 103 publications

Island disharmony revisited using orchids as a model group

Island disharmony revisited using orchids as a model group

Similarity in mycorrhizal communities associating with two widespread terrestrial orchids decays with distance

Host Tree Identity Influences Leaf Nutrient Relations of the Epiphyte Dendrobium guamense Ames.

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