| 1. |
- Kennedy, Peter G, et al.
(author)
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Scaling up : examining the macroecology of ectomycorrhizal fungi.
- 2012
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In: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 21:17, s. 4151-4
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Journal article (peer-reviewed)abstract
- Ectomycorrhizal (ECM) fungi play major ecological roles in temperate and tropical ecosystems. Although the richness of ECM fungal communities and the factors controlling their structure have been documented at local spatial scales, how they vary at larger spatial scales remains unclear. In this issue of Molecular Ecology, Tedersoo et al. (2012) present the results of a meta-analysis of ECM fungal community structure that sheds important new light on global-scale patterns. Using data from 69 study systems and 6021 fungal species, the researchers found that ECM fungal richness does not fit the classic latitudinal diversity gradient in which species richness peaks at lower latitudes. Instead, richness of ECM fungal communities has a unimodal relationship with latitude that peaks in temperate zones. Intriguingly, this conclusion suggests the mechanisms driving ECM fungal community richness may differ from those of many other organisms, including their plant hosts. Future research will be key to determine the robustness of this pattern and to examine the processes that generate and maintain global-scale gradients of ECM fungal richness.
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| 2. |
- Tedersoo, Leho, et al.
(author)
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Towards global patterns in the diversity and community structure of ectomycorrhizal fungi.
- 2012
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In: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 21:17, s. 4160-70
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Journal article (peer-reviewed)abstract
- Global species richness patterns of soil micro-organisms remain poorly understood compared to macro-organisms. We use a global analysis to disentangle the global determinants of diversity and community composition for ectomycorrhizal (EcM) fungi-microbial symbionts that play key roles in plant nutrition in most temperate and many tropical forest ecosystems. Host plant family has the strongest effect on the phylogenetic community composition of fungi, whereas temperature and precipitation mostly affect EcM fungal richness that peaks in the temperate and boreal forest biomes, contrasting with latitudinal patterns of macro-organisms. Tropical ecosystems experience rapid turnover of organic material and have weak soil stratification, suggesting that poor habitat conditions may contribute to the relatively low richness of EcM fungi, and perhaps other soil biota, in most tropical ecosystems. For EcM fungi, greater evolutionary age and larger total area of EcM host vegetation may also contribute to the higher diversity in temperate ecosystems. Our results provide useful biogeographic and ecological hypotheses for explaining the distribution of fungi that remain to be tested by involving next-generation sequencing techniques and relevant soil metadata.
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| 3. |
- Looney, Brian P., et al.
(author)
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Into and out of the tropics : global diversification patterns in a hyperdiverse clade of ectomycorrhizal fungi
- 2016
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In: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 25:2, s. 630-647
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Journal article (peer-reviewed)abstract
- Ectomycorrhizal (ECM) fungi, symbiotic mutualists of many dominant tree and shrub species, exhibit a biogeographic pattern counter to the established latitudinal diversity gradient of most macroflora and fauna. However, an evolutionary basis for this pattern has not been explicitly tested in a diverse lineage. In this study, we reconstructed a mega-phylogeny of a cosmopolitan and hyperdiverse genus of ECM fungi, Russula, sampling from annotated collections and utilizing publically available sequences deposited in GenBank. Metadata from molecular operational taxonomic unit cluster sets were examined to infer the distribution and plant association of the genus. This allowed us to test for differences in patterns of diversification between tropical and extratropical taxa, as well as how their associations with different plant lineages may be a driver of diversification. Results show that Russula is most species-rich at temperate latitudes and ancestral state reconstruction shows that the genus initially diversified in temperate areas. Migration into and out of the tropics characterizes the early evolution of the genus, and these transitions have been frequent since this time. We propose the generalized diversification rate' hypothesis to explain the reversed latitudinal diversity gradient pattern in Russula as we detect a higher net diversification rate in extratropical lineages. Patterns of diversification with plant associates support host switching and host expansion as driving diversification, with a higher diversification rate in lineages associated with Pinaceae and frequent transitions to association with angiosperms.
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| 4. |
- Ryberg, Martin
(author)
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Molecular operational taxonomic units as approximations of species in the light of evolutionary models and empirical data from Fungi
- 2015
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In: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 24:23, s. 5770-5777
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Journal article (other academic/artistic)abstract
- During the last couple of decades, an increasing number of studies use sequence clusters as units for taxonomic diversity. It is well known that such molecular operational taxonomic units (MOTUs) do not necessarily correspond to species, but they are treated as such when measuring diversity and testing theories. Here, I show that data from studies of molecular evolution and species diversification of fungi indicate that commonly used cut-offs are likely to lump species in many cases. At the same time, empirical studies show that the mean within-species variation is close to these cut-offs. That the within-species variation estimates are plausible is supported by coalescence modelling under a range of parameter settings. In addition, studies using crossing tests to delimit species show that there often is an overlap in within- and between-species distances. The available data therefore indicate that sequence clusters are likely to misrepresent species. However, to keep a biological relevance, MOTUs should be kept in close agreement with species. Studies using them should therefore asses how sensitive the results are to differences between MOTUs and species - something that is rarely done. An even better solution is to directly include the uncertainty in species delimitation in the analyses, but in many cases, we need to increase our knowledge of taxonomy and evolution to do this accurately. Even if the empirical data referred to here pertain to the barcoding region of rDNA in fungi, there is nothing indicating that the situation is substantially better for other taxa or genes.
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| 5. |
- Tedersoo, Leho, et al.
(author)
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Global biogeography of the ectomycorrhizal/sebacina lineage (Fungi, Sebacinales) as revealed from comparative phylogenetic analyses
- 2014
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In: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 23:16, s. 4168-4183
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Journal article (peer-reviewed)abstract
- Compared with plants and animals, large-scale biogeographic patterns of microbes including fungi are poorly understood. By the use of a comparative phylogenetic approach and ancestral state reconstructions, we addressed the global biogeography, rate of evolution and evolutionary origin of the widely distributed ectomycorrhizal (EcM) /sebacina lineage that forms a large proportion of the Sebacinales order. We downloaded all publicly available internal transcribed spacer (ITS) sequences and metadata and supplemented sequence information from three genes to construct dated phylogenies and test biogeographic hypotheses. The /sebacina lineage evolved 45-57Myr ago that groups it with relatively young EcM taxa in other studies. The most parsimonious origin for /sebacina is inferred to be North American temperate coniferous forests. Among biogeographic traits, region and biome exhibited stronger phylogenetic signal than host family. Consistent with the resource availability (environmental energy) hypothesis, the ITS region is evolving at a faster rate in tropical than nontropical regions. Most biogeographic regions exhibited substantial phylogenetic clustering suggesting a strong impact of dispersal limitation over a large geographic scale. In northern Holarctic regions, however, phylogenetic distances and phylogenetic grouping of isolates indicate multiple recent dispersal events.
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