Håvard Kauserud

• Aas, Anders Bjørnsgard; Andrew, Carrie Joy; Blaalid, Rakel; Vik, Unni; Kauserud, Håvard & Davey, Marie Louise (2019). Fine-scale diversity patterns in belowground microbial communities are consistent across kingdoms. FEMS Microbiology Ecology.  ISSN 0168-6496.  95(6), s 1- 11 . doi: 10.1093/femsec/fiz058 Vis sammendrag

  The belowground environment is heterogeneous and complex at fine spatial scales. Physical structures, biotic components and abiotic conditions create a patchwork mosaic of potential niches for microbes. Questions remain about mechanisms and patterns of community assembly belowground, including: Do fungal and bacterial communities assemble differently? How do microbes reach the roots of host plants? Within a 4 m2 plot in alpine vegetation, high throughput sequencing of the 16S (bacteria) and ITS1 (fungal) ribosomal RNA genes was used to characterise microbial community composition in roots and adjacent soil of a viviparous host plant (Bistorta vivipara). At fine spatial scales, beta-diversity patterns in belowground bacterial and fungal communities were consistent, although compositional change was greater in bacteria than fungi. Spatial structure and distance-decay relationships were also similar for bacteria and fungi, with significant spatial structure detected at <50 cm among root- but not soil-associated microbes. Recruitment of root microbes from the soil community appeared limited at this sampling and sequencing depth. Possible explanations for this include recruitment from low-abundance populations of soil microbes, active recruitment from neighbouring plants and/or vertical transmission of symbionts to new clones, suggesting varied methods of microbial community assembly for viviparous plants. Our results suggest that even at relatively small spatial scales, deterministic processes play a significant role in belowground microbial community structure and assembly.

• Andrew, Carrie Joy; Büntgen, Ulf; Egli, Simon; Senn-Irlet, Beatrice; Grytnes, John-Arvid; Heilmann-Clausen, Jacob; Boddy, Lynne; Bässler, Claus; Gange, Alan C.; Heegaard, Einar; Høiland, Klaus; Kirk, Paul M.; Krisai-Greilhüber, Irmgard; Kuyper, Thomas W. & Kauserud, Håvard (2019). Open-source data reveal how collections-based fungal diversity is sensitive to global change. Applications in Plant Sciences.  ISSN 2168-0450.  7(3), s 1- 19 . doi: 10.1002/aps3.1227 Fulltekst i vitenarkiv. Vis sammendrag

  Premise of the Study Fungal diversity (richness) trends at large scales are in urgent need of investigation, especially through novel situations that combine long‐term observational with environmental and remotely sensed open‐source data. Methods We modeled fungal richness, with collections‐based records of saprotrophic (decaying) and ectomycorrhizal (plant mutualistic) fungi, using an array of environmental variables across geographical gradients from northern to central Europe. Temporal differences in covariables granted insight into the impacts of the shorter‐ versus longer‐term environment on fungal richness. Results Fungal richness varied significantly across different land‐use types, with highest richness in forests and lowest in urban areas. Latitudinal trends supported a unimodal pattern in diversity across Europe. Temperature, both annual mean and range, was positively correlated with richness, indicating the importance of seasonality in increasing richness amounts. Precipitation seasonality notably affected saprotrophic fungal diversity (a unimodal relationship), as did daily precipitation of the collection day (negatively correlated). Ectomycorrhizal fungal richness differed from that of saprotrophs by being positively associated with tree species richness. Discussion Our results demonstrate that fungal richness is strongly correlated with land use and climate conditions, especially concerning seasonality, and that ongoing global change processes will affect fungal richness patterns at large scales.

• Andrew, Carrie; Diez, Jeffrey; James, Timothy Y. & Kauserud, Håvard (2019). Fungarium specimens: a largely untapped source in global change biology and beyond. Philosophical Transactions of the Royal Society of London. Biological Sciences.  ISSN 0962-8436.  374(1763), s 1- 11 . doi: 10.1098/rstb.2017.0392
• Asplund, Johan; Kauserud, Håvard; Ohlson, Mikael & Nybakken, Line (2019). Spruce and beech as local determinants of forest fungal community structure in litter, humus and mineral soil. FEMS Microbiology Ecology.  ISSN 0168-6496.  95(2) . doi: 10.1093/femsec/fiy232
• Botnen, Synnøve Smebye; Davey, Marie Louise; Aas, Anders Bjørnsgard; Carlsen, Tor; Thoen, Ella; Heegaard, Einar; Vik, Unni; Dresch, Philipp; Mundra, Sunil; Peintner, Ursula; Taylor, Andy F. S. & Kauserud, Håvard (2019). Biogeography of plant root-associated fungal communities in the North Atlantic region mirrors climatic variability. Journal of Biogeography.  ISSN 0305-0270.  46(7), s 1532- 1546 . doi: 10.1111/jbi.13613 Vis sammendrag

  Aim Polar and alpine ecosystems appear to be particularly sensitive to increasing temperatures and the altered precipitation patterns linked to climate change. However, little is currently known about how these environmental drivers may affect edaphic organisms within these ecosystems. In this study, we examined communities of plant root‐associated fungi (RAF) over large biogeographical scales and along climatic gradients in the North Atlantic region in order to gain insights into the potential effects of climate variability on these communities. We also investigated whether selected fungal traits were associated with particular climates. Locations Austria, Scotland, Mainland Norway, Iceland, Jan Mayen and Svalbard. Taxa Root fungi associated with the ectomycorrhizal and herbaceous plant Bistorta vivipara. Methods DNA metabarcoding of the ITS1 region was used to characterize the RAF of 302 whole plant root systems, which were analysed by means of ordination methods and linear modelling. Fungal spore length, width, volume and shape, as well as mycelial exploration type (ET) of ectomycorrhizal (ECM) basidiomycetes were summarized at a community level. Results The RAF communities exhibited strong biogeographical structuring, and both compositional variation as well as fungal species richness correlated with annual temperature and precipitation. In accordance with general island biogeography theory, the least species‐rich RAF communities were found on Jan Mayen, a remote and small island in the North Atlantic Ocean. Fungal spores tended to be more elongated with increasing latitude. We also observed a climate effect on which mycelial ET was dominating among the ectomycorrhizal fungi. Main conclusions Both geographical and environmental variables were important for shaping root‐associated fungal communities at a North Atlantic scale, including the High Arctic. Fungal OTU richness followed general biogeographical patterns and decreased with decreasing size and/or increasing isolation of the host plant population. The probability of possessing more elongated spores increases with latitude, which may be explained by a selection for greater dispersal capacity among more isolated host plant populations in the Arctic.

• Krah, Franz-Sebastian; Büntgen, Ulf; Schaefer, Hanno; Müller, Jörg; Andrew, Carrie; Boddy, Lynne; Diez, Jeffrey; Egli, Simon; Freckleton, Robert; Gange, Alan C.; Halvorsen, Rune; Heegaard, Einar; Heideroth, Antje; Heibl, Christoph; Heilmann-Clausen, Jacob; Høiland, Klaus; Kar, Ritwika; Kauserud, Håvard; Kirk, Paul M.; Kuyper, Thomas W.; Krisai-Greilhuber, Irmgard; Nordén, Jenni; Papastefanou, Phillip; Senn-Irlet, Beatrice & Bässler, Claus (2019). European mushroom assemblages are darker in cold climates. Nature Communications.  ISSN 2041-1723. . doi: 10.1038/s41467-019-10767-z Vis sammendrag

  Thermal melanism theory states that dark-colored ectotherm organisms are at an advantage at low temperature due to increased warming. This theory is generally supported for ectotherm animals, however, the function of colors in the fungal kingdom is largely unknown. Here, we test whether the color lightness of mushroom assemblages is related to climate using a dataset of 3.2 million observations of 3,054 species across Europe. Consistent with the thermal melanism theory, mushroom assemblages are significantly darker in areas with cold climates. We further show differences in color phenotype between fungal lifestyles and a lifestyle differentiated response to seasonality. These results indicate a more complex ecological role of mushroom colors and suggest functions beyond thermal adaption. Because fungi play a crucial role in terrestrial carbon and nutrient cycles, understanding the links between the thermal environment, functional coloration and species’ geographical distributions will be critical in predicting ecosystem responses to global warming.

• Straumfors, Anne; Foss, Oda Astrid Haarr; Fuss, Janina; Mollerup, Steen Kristen; Kauserud, Håvard & Mundra, Sunil (2019). Exposure characterization and diversity of the inhalable mycobiome of sawmill workers. Applied and Environmental Microbiology.  ISSN 0099-2240. . doi: 10.1128/AEM.01448-19 Vis sammendrag

  Exposure to fungal spores has been associated with respiratory symptoms and allergic alveolitis among sawmill workers, but the complexity of sawmill workers' fungal exposure has been poorly studied. We characterized the fungal diversity in air samples from sawmill workers' breathing zone, and identified differences in richness, diversity and taxonomic composition between companies, departments, wood types and seasons. Full-shift personal inhalable dust samples (n=86) collected from 11 industrial saw-, sorting-, and planer mill companies processing spruce and/or pine were subjected to DNA metabarcoding using the fungal Internal Transcribed Spacer (ITS) region 2. The workers were exposed to a higher total number of operational taxonomic units (OTUs) in summer compared to winter, and when processing spruce compared with pine. Workers in the saw department had the richest fungal exposure followed by workers in the planing department and sorting of dry timber department. Sawmills explained 11% of the variation in fungal community composition of the exposure, followed by season (5%) and departments (3%). The fungal composition of the exposure differed between season, sawmills, wood types and departments also at the taxonomic levels, from phylum to species level. The differences in exposure diversity suggests that potential health effects of fungal inhalation also may be different, hence a risk assessment based on the fungal diversity differences should be performed. This study may serve as a basis towards establishing a fungal profile of signature species that are specific for sawmills and can be measured quantitatively in future risk assessments of sawmill workers.

• Thoen, Ella; Aas, Anders Bjørnsgard; Vik, Unni; Brysting, Anne Krag; Skrede, Inger; Carlsen, Tor & Kauserud, Håvard (2019). A single ectomycorrhizal plant root system includes a diverse and spatially structured fungal community. Mycorrhiza.  ISSN 0940-6360.  29(3), s 167- 180 . doi: 10.1007/s00572-019-00889-z
• Andrew, Carrie Joy; Halvorsen, Rune; Heegaard, Einar; Kuyper, Thomas W.; Heilmann-Clausen, Jacob; Krisai-Greilhuber, Irmgard; Bässler, Claus; Egli, Simon; Gange, Alan C.; Høiland, Klaus; Kirk, Paul M.; Senn-Irlet, Beatrice; Boddy, Lynne; Büntgen, Ulf & Kauserud, Håvard (2018). Continental-scale macrofungal assemblage patterns correlate with climate, soil carbon and nitrogen deposition. Journal of Biogeography.  ISSN 0305-0270.  45(8), s 1942- 1953 . doi: 10.1111/jbi.13374 Vis sammendrag

  Aim:Macroecological scales of species compositional trends are well documentedfor a variety of plant and animal groups, but remain sparse for fungi, despite theirecological importance in carbon and nutrient cycling. It is, thus, essential to under-stand the composition of fungal assemblages across broad geographical scales andthe underlying drivers. Our overall aim was to describe these patterns for fungiacross two nutritional modes (saprotrophic and ectomycorrhizal). Furthermore, weaimed to elucidate the temporal component of fruiting patterns and to relate theseto soil carbon and nitrogen deposition. Location:Central and Northern Europe.Methods:A total of 4.9 million fungal fruit body observations throughout Europe,collected between 1970 and 2010, were analysed to determine the two main envi-ronmental and geographical gradients structuring fungal assemblages for two mainnutritional modes, saprotrophic and ectomycorrhizal fungi. Results:Two main gradients explaining the geography of compositional patternswere identified, for each nutritional mode. Mean annual temperature (and relatedcollinear, seasonal measures) correlated most strongly with the first gradient forboth nutritional modes. Soil organic carbon was the highest correlate of the second compositional gradient for ectomycorrhizal fungi, suspected as an indicator of vege-tation- and pH-related covariates. In contrast, nitrogen deposition constituted asecond gradient for saprotrophic fungi, likely a proxy for anthropogenic pollution.Compositional gradients and environmental conditions correlated similarly whenthe data were divided into two time intervals of 1970–1990 and 1991–2010.Evidence of compositional temporal change was highest with increasing elevationand latitude. Main conclusions:Fungal assemblage patterns demonstrate clear biogeographicalpatterns that relate the nutritional modes to their main environmental correlates oftemperature, soil organic carbon and nitrogen deposition. With respect to globalchange impacts, the highest rates of compositional change by time suggest targetinghigher latitudes and elevations for a better understanding of fungal dynamics. We,finally, suggest further examination of the ranges and dispersal abilities of fungi tobetter assess responses to global change.

• Andrew, Carrie Joy; Heegaard, Einar; Gange, Alan C.; Senn-Irlet, Beatrice; Egli, Simon; Kirk, Paul M.; Büntgen, Ulf; Kauserud, Håvard & Boddy, Lynne (2018). Congruency in fungal phenology patterns across dataset sources and scales. Fungal ecology.  ISSN 1754-5048.  32, s 9- 17 . doi: 10.1016/j.funeco.2017.11.009 Vis sammendrag

  As citizen science and digitization projects bring greater and larger datasets to the scientific realm, wemust address the comparability of results across varying sources and spatial scales. Independentlyassembled fungal fruit body datasets from Switzerland and the UK were available at large, national-scales and more intensively surveyed, local-scales. Phenology responses of fungi between these data-sets at different scales (national, intermediate and local) resembled one another. Consistently with time,the fruiting season initiated earlier and extended later. Phenology better correlated across data sourcesand scales in the UK, which contain less landscape and environmental heterogeneity than Switzerland.Species-specific responses in seasonality varied more than overall responses, but generally fruiting startdates were later for most Swiss species compared with UK species, while end dates were later for both.The coherency of these results, across the data sources, supports the use of presence-only data obtainedby multiple recorders, and even across heterogeneous landscapes, for global change phenology research.

• Andrew, Carrie Joy; Heegaard, Einar; Høiland, Klaus; Senn-Irlet, Beatrice; Kuyper, Thomas W.; Krisai-Greilhuber, Irmgard; Kirk, Paul M.; Heilmann-Clausen, Jacob; Gange, Alan C.; Egli, Simon; Bässler, Claus; Büntgen, Ulf; Boddy, Lynne & Kauserud, Håvard (2018). Explaining European fungal fruiting phenology with climate variability. Ecology.  ISSN 0012-9658.  99(6), s 1306- 1315 . doi: 10.1002/ecy.2237 Fulltekst i vitenarkiv. Vis sammendrag

  Here we assess the impact of geographically dependent (latitude, longitude, and altitude) changes in bioclimatic (temperature, precipitation, and primary productivity) variability on fungal fruiting phenology across Europe. Two main nutritional guilds of fungi, saprotrophic and ectomycorrhizal, were further separated into spring and autumn fruiters. We used a path analysis to investigate how biogeographic patterns in fungal fruiting phenology coincided with seasonal changes in climate and primary production. Across central to northern Europe, mean fruiting varied by approximately 25 d, primarily with latitude. Altitude affected fruiting by up to 30 d, with spring delays and autumnal accelerations. Fruiting was as much explained by the effects of bioclimatic variability as by their large‐scale spatial patterns. Temperature drove fruiting of autumnal ectomycorrhizal and saprotrophic groups as well as spring saprotrophic groups, while primary production and precipitation were major drivers for spring‐fruiting ectomycorrhizal fungi. Species‐specific phenology predictors were not stable, instead deviating from the overall mean. There is significant likelihood that further climatic change, especially in temperature, will impact fungal phenology patterns at large spatial scales. The ecological implications are diverse, potentially affecting food webs (asynchrony), nutrient cycling and the timing of nutrient availability in ecosystems.

• Asplund, Johan; Kauserud, Håvard; Bokhorst, Stef; Lie, Marit Helene; Ohlson, Mikael & Nybakken, Line (2018). Fungal communities influence decomposition rates of plant litter from two dominant tree species. Fungal ecology.  ISSN 1754-5048.  32, s 1- 8 . doi: 10.1016/j.funeco.2017.11.003
• Balasundaram, Sudhagar; Hess, Jaqueline; Durling, Mikael Brandström; Moody, Suzy C.; Thorbek, Birgitte Lisbeth Graae; Progida, Cinzia; LaButti, Kurt; Aerts, Andrea L.; Barry, Kerrie; Grigoriev, Igor V.; Boddy, Lynne; Högberg, Nils; Kauserud, Håvard; Eastwood, Daniel C. & Skrede, Inger (2018). The fungus that came in from the cold: dry rot’s pre-adapted ability to invade buildings. The ISME Journal.  ISSN 1751-7362.  12(3), s 791- 801 . doi: 10.1038/s41396-017-0006-8
• Botnen, Synnøve Smebye; Davey, Marie Louise; Halvorsen, Rune & Kauserud, Håvard (2018). Sequence clustering threshold has little effect on the recovery of microbial community structure. Molecular Ecology Resources.  ISSN 1755-098X.  18(5), s 1064- 1076 . doi: 10.1111/1755-0998.12894
• Gange, Alan C.; Heegaard, Einar; Boddy, Lynne; Andrew, Carrie Joy; Kirk, Paul M.; Halvorsen, Rune; Kuyper, Thomas W.; Bässler, Claus; Diez, Jefferey M.; Heilman-Clausen, Jacob; Høiland, Klaus; Büntgen, Ulf & Kauserud, Håvard (2018). Trait-dependent distributional shifts in fruiting of common British fungi. Ecography.  ISSN 0906-7590.  41(1), s 51- 61 . doi: 10.1111/ecog.03233 Vis sammendrag

  Despite the dramatic phenological responses of fungal fruiting to recent climate warming, it is unknown whether spatial distributions of fungi have changed and to what extent such changes are influenced by fungal traits, such as ectomycorrhizal (ECM) or saprotrophic lifestyles, spore characteristics, or fruit body size. Our overall aim was to understand how climate and fungal traits determine whether and how species‐specific fungal fruit body abundances have shifted across latitudes over time, using the UK national database of fruiting records. The data employed were recorded over 45 yr (1970–2014), and include 853 278 records of Agaricales, Boletales and Russulales, though we focus only on the most common species (with more than 3000 records each). The georeferenced observations were analysed by a Bayesian inference as a Gaussian additive model with a specification following a joint species distribution model. We used an offset, random contributions and fixed effects to isolate different potential biases from the trait‐specific interactions with latitude/climate and time. Our main aim was assessed by examination of the three‐way‐interaction of trait, predictor (latitude or climate) and time. The results show a strong trait‐specific shift in latitudinal abundance through time, as ECM species have become more abundant relative to saprotrophic species in the north. Along precipitation gradients, phenology was important, in that species with shorter fruiting seasons have declined markedly in abundance in oceanic regions, whereas species with longer seasons have become relatively more common overall. These changes in fruit body distributions are correlated with temperature and rainfall, which act directly on both saprotrophic and ECM fungi, and also indirectly on ECM fungi, through altered photosynthate allocation from their hosts. If these distributional changes reflect fungal activity, there will be important consequences for the responses of forest ecosystems to changing climate, through effects on primary production and nutrient cycling.

• Jacobsen, Rannveig Margrete; Sverdrup-Thygeson, Anne; Kauserud, Håvard & Birkemoe, Tone (2018). Revealing hidden insect–fungus interactions; moderately specialized, modular and anti-nested detritivore networks. Proceedings of the Royal Society of London. Biological Sciences.  ISSN 0962-8452.  285 . doi: 10.1098/rspb.2017.2833 Fulltekst i vitenarkiv. Vis sammendrag

  Ecological networks are composed of interacting communities that influence ecosystem structure and function. Fungi are the driving force for ecosystem processes such as decomposition and carbon sequestration in terrestrial habitats, and are strongly influenced by interactions with invertebrates. Yet, interactions in detritivore communities have rarely been considered froma network perspective. In the present study, we analyse the interaction networks between three functional guilds of fungi and insects sampled from dead wood. Using DNA metabarcoding to identify fungi, we reveal a diversity of interactions differing in specificity in the detritivore networks, involving three guilds of fungi. Plant pathogenic fungi were relatively unspecialized in their interactions with insects inhabiting dead wood, while interactions between the insects and wood-decay fungi exhibited the highest degree of specialization, which was similar to estimates for animal-mediated seed dispersal networks in previous studies. The low degree of specialization for insect symbiont fungi was unexpected. In general, the pooled insect–fungus networks were significantly more specialized, more modular and less nested than randomized networks. Thus, the detritivore networks had an unusual anti-nested structure. Future studies might corroborate whether this is a common aspect of networks based on interactions with fungi, possibly owing to their often intense competition for substrate.

• Jacobsen, Rannveig Margrete; Sverdrup-Thygeson, Anne; Kauserud, Håvard; Mundra, Sunil & Birkemoe, Tone (2018). Exclusion of invertebrates influences saprotrophic fungal community and wood decay rate in an experimental field study. Functional Ecology.  ISSN 0269-8463.  32(11), s 2571- 2582 . doi: 10.1111/1365-2435.13196 Fulltekst i vitenarkiv. Vis sammendrag

  1. Decomposer communities perform an essential ecosystem function by recycling nutrients. However, the effect of higher trophic levels on microbial decomposer communities and rate of decomposition is poorly understood. We therefore conducted an exclusion experiment to test the effect of invertebrates on fungal decomposer communities in dead wood, repeated at 30 sites in two landscapes, and measured wood density to assess effect on decay rate. 2. Invertebrates were excluded from recently cut logs by cages with a 1‐mm‐mesh net, and fungal communities in caged logs were compared to logs accessible to invertebrates by DNA metabarcoding analyses. Accessible logs included control logs, cage control logs and positive control logs. 3. We found that exclusion of invertebrates had a significant effect on fungal community composition. For example, the wood decay fungi Trametes versicolor and T. ochracea were significantly more abundant in accessible logs than in caged logs. The strongest effect on fungal community composition, however, was attributed to differing baseline conditions in the individual trees. When accounting for these baseline differences, caged logs had significantly higher wood density than control logs after 2 years, indicating lower rates of wood decay in caged logs. 4. Further studies, spanning several years, are required to fully understand the influence of invertebrates on fungi and wood decay. However, our results indicate that invertebrates influence both the composition of saprotrophic communities in dead wood and their decomposition function, which is vital to forest ecosystems. community assembly, dead wood, decomposition, DNA, high‐throughput sequencing, insects, saproxylic, top‐down

• Khomich, Maryia; Cox, Filipa; Andrew, Carrie Joy; Andersen, Tom; Kauserud, Håvard & Davey, Marie Louise (2018). Coming up short: Identifying substrate and geographic biases in fungal sequence databases. Fungal ecology.  ISSN 1754-5048.  36, s 75- 80 . doi: 10.1016/j.funeco.2018.08.002 Fulltekst i vitenarkiv. Vis sammendrag

  Insufficient reference database coverage is a widely recognized limitation of molecular ecology ap-proaches which are reliant on database matches for assignment of function or identity. Here, we use datafrom 65 amplicon high-throughput sequencing (HTS) datasets targeting the internal transcribed spacer(ITS) region of fungal rDNA to identify substrates and geographic areas whose underrepresentation in theavailable reference databases could have meaningful impact on our ability to draw ecological conclu-sions. A total of 14 different substrates were investigated. Database representation was particularly poorfor the fungal communities found in aquatic (freshwater and marine) and soil ecosystems. Aquaticecosystems are identified as priority targets for the recovery of novel fungal lineages. A subset of the datarepresenting soil samples with global distribution were used to identify geographic locations andterrestrial biomes with poor database representation. Database coverage was especially poor in tropical,subtropical, and Antarctic latitudes, and the Amazon, Southeast Asia, Australasia, and the Indian sub-continent are identified as priority areas for improving database coverage in fungi.

• Aas, Anders Bjørnsgard; Davey, Marie Louise & Kauserud, Håvard (2017). ITS all right mama: investigating the formation of chimeric sequences in the ITS2 region by DNA metabarcoding analyses of fungal mock communities of different complexities. Molecular Ecology Resources.  ISSN 1755-098X.  17(4), s 730- 741 . doi: 10.1111/1755-0998.12622
• Andrew, Carrie Joy; Heegaard, Einar; Kirk, Paul M.; Bässler, Claus; Heilmann-Clausen, Jacob; Krisai-Greilhuber, Irmgard; Kuyper, Thomas W.; Senn-Irlet, Beatrice; Büntgen, Ulf; Diez, Jeffrey Michael; Egli, Simon; Gange, Alan C.; Halvorsen, Rune; Høiland, Klaus; Nordén, Jenni; Rustøen, Fredrik; Boddy, Lynne & Kauserud, Håvard (2017). Big data integration: Pan-European fungal species observations' assembly for addressing contemporary questions in ecology and global change biology. Fungal Biology Reviews.  ISSN 1749-4613.  31(2), s 88- 98 . doi: 10.1016/j.fbr.2017.01.001 Vis sammendrag

  Species occurrence observations are increasingly available for scientific analyses through citizen science projects and digitization of museum records, representing a largely untapped ecological resource. When combined with open-source data, there is unparalleled potential for understanding many aspects of the ecology and biogeography of organisms. Here we describe the process of assembling a pan-European mycological meta-database (ClimFun) and integrating it with open-source data to advance the fields of macroecology and biogeography against a backdrop of global change. Initially 7.3 million unique fungal species fruit body records, spanning nine countries, were processed and assembled into 6 million records of more than 10,000 species. This is an extraordinary amount of fungal data to address macro-ecological questions. We provide two examples of fungal species with different life histories, one ectomycorrhizal and one wood decaying, to demonstrate how such continental-scale meta-databases can offer unique insights into climate change effects on fungal phenology and fruiting patterns in recent decades. Keywords Biogeography; Citizen science; Fungi; Global change; Meta-database; Open-source

• Cross, Hugh; Sønstebø, Jørn Henrik; Nagy, Nina Elisabeth; Timmermann, Volkmar; Solheim, Halvor; Børja, Isabella; Kauserud, Håvard; Carlsen, Tor; Rzepka, Barbara; Wasak, Katarzyna; Vivian-Smith, Adam & Hietala, Ari Mikko (2017). Fungal diversity and seasonal succession in ash leaves infected by the invasive ascomycete Hymenoscyphus fraxineus. New Phytologist.  ISSN 0028-646X.  213(3), s 1405- 1417 . doi: 10.1111/nph.14204 Fulltekst i vitenarkiv. Vis sammendrag

  High biodiversity is regarded as a barrier against biological invasions. We hypothesized that the invasion success of the pathogenic ascomycete Hymenoscyphus fraxineus threatening common ash in Europe relates to differences in dispersal and colonization success between the invader and the diverse native competitors. Ash leaf mycobiome was monitored by high-throughput sequencing of the fungal internal transcribed spacer region (ITS) and quantitative PCR profiling of H. fraxineus DNA. Initiation of ascospore production by H. fraxineus after overwintering was followed by pathogen accumulation in asymptomatic leaves. The induction of necrotic leaf lesions coincided with escalation of H. fraxineus DNA levels and changes in proportion of biotrophs, followed by an increase of ubiquitous endophytes with pathogenic potential. H. fraxineus uses high propagule pressure to establish in leaves as quiescent thalli that switch to pathogenic mode once these thalli reach a certain threshold – the massive feedback from the saprophytic phase enables this fungus to challenge host defenses and the resident competitors in mid-season when their density in host tissues is still low. Despite the general correspondence between the ITS-1 and ITS-2 datasets, marker biases were observed, which suggests that multiple barcodes provide better overall representation of mycobiomes.

• Davey, Marie Louise; Skogen, Marte; Heegaard, Einar; Halvorsen, Rune; Kauserud, Håvard & Ohlson, Mikael (2017). Host and tissue variations overshadow the response of boreal moss-associated fungal communities to increased nitrogen load. Molecular Ecology.  ISSN 0962-1083.  26(2), s 571- 588 . doi: 10.1111/mec.13938 Vis sammendrag

  Human activity has more than doubled the amount of nitrogen entering the global nitrogen cycle, and the boreal forest biome is a nitrogen-limited ecosystem sensitive to nitrogen load perturbation. Although bryophyte-associated microbes contribute significantly to boreal forest ecosystem function, particularly in carbon and nitrogen cycling, little is known about their responses to anthropogenic global change. Amplicon pyrosequencing of the ITS2 region of rDNA was used to investigate how fungal communities associated with three bryophyte species responded to increased nitrogen loads in a long-term fertilization experiment in a boreal Picea abies forest in southern Norway. Overall, OTU richness, community composition and the relative abundance of specific ecological guilds were primarily influenced by host species identity and tissue type. Although not the primary factor affecting fungal communities, nitrogen addition did impact the abundance of specific guilds of fungi and the resulting overall community composition. Increased nitrogen loads decreased ectomycorrhizal abundance, with Amphinema, Cortinarius, Russula and Tylospora OTUs responding negatively to fertilization. Pathogen abundance increased with fertilization, particularly in the moss pathogen Eocronartium. Saprophytic fungi were both positively and negatively impacted by the nitrogen addition, indicating a complex community level response. The overshadowing of the effects of increased nitrogen loads by variation related to host and tissue type highlights the complexity of bryophyte-associated microbial communities and the intricate nature of their responses to anthropogenic global change.

• Dunthorn, Micah; Kauserud, Håvard; Bass, David; Mayor, Jordan & Mahé, Frédéric (2017). Yeasts dominate soil fungal communities in three lowland Neotropical rainforests. Environmental Microbiology Reports.  ISSN 1758-2229.  9(5), s 668- 675 . doi: 10.1111/1758-2229.12575
• Grube, Martin; Gaya, Ester; Kauserud, Håvard; Smith, Adrian M.; Avery, Simon V.; Fernstad, Sara F.; Muggia, Lucia; Martin, Michael David; Eivindsen, Tove; Kõljalg, Urmas & Bendiksby, Mika (2017). The next generation fungal diversity researcher. Fungal Biology Reviews.  ISSN 1749-4613.  31(3), s 124- 130 . doi: 10.1016/j.fbr.2017.02.001 Fulltekst i vitenarkiv. Vis sammendrag

  Fungi are more important to our lives than is assumed by the general public. They can comprise both devastating pathogens and plant-associated mutualists in nature, and several species have also become important workhorses of biotechnology. Fungal diversity research has in a short time transcended from a low-tech research area to a methodintensive high-tech discipline. With the advent of the new genomic and post-genomic methodologies, large quantities of new fungal data are currently becoming available each year. Whilst these new data and methodologies may help modern fungal diversity researchers to explore and discover the yet hidden diversity within a context of biological processes and organismal diversity, they need to be reconciled with the traditional approaches. Such a synthesis is actually difficult to accomplish given the current discouraging situation of fungal biology education, especially in the areas of biodiversity and taxonomic research. The number of fungal diversity researchers and taxonomists in academic institutions is decreasing, as are opportunities for mycological education in international curricula. How can we educate and stimulate students to pursue a career in fungal diversity research and taxonomy and avoid the situation whereby only those few institutions with strong financial support are able to conduct excellent research? Our short answer is that we need a combination of increased specialization and increased collaboration, i.e. that scientists with specialized expertise (e.g., in data generation, compilation, interpretation, and communication) consistently work together to generate and delivernew fungal knowledge in a more integrative manner e closing the gap between both traditional and modern approaches and academic and non-academic environments. Here we discuss how this perspective could be implemented in the training of the ‘next generation fungal diversity researcher’.

• Jacobsen, Rannveig M; Kauserud, Håvard; Sverdrup-Thygeson, Anne; Bjorbækmo, Marit Markussen & Birkemoe, Tone (2017). Wood-inhabiting insects can function as targeted vectors for decomposer fungi. Fungal ecology.  ISSN 1754-5048.  29, s 76- 84 . doi: 10.1016/j.funeco.2017.06.006
• Khomich, Maryia; Davey, Marie Louise; Kauserud, Håvard; Rasconi, Serena & Andersen, Tom (2017). Fungal communities in Scandinavian lakes along a longitudinal gradient. Fungal ecology.  ISSN 1754-5048.  27, s 36- 46 . doi: 10.1016/j.funeco.2017.01.008 Fulltekst i vitenarkiv.
• Khomich, Maryia; Kauserud, Håvard; Logares, Ramiro; Rasconi, Serena & Andersen, Tom (2017). Planktonic protistan communities in lakes along a large-scale environmental gradient. FEMS Microbiology Ecology.  ISSN 0168-6496.  93(4) . doi: 10.1093/femsec/fiw231 Fulltekst i vitenarkiv.
• Lorberau, Kelsey; Botnen, Synnøve Smebye; Mundra, Sunil; Aas, Anders Bjørnsgard; Rozema, Jelte; Eidesen, Pernille Bronken & Kauserud, Håvard (2017). Does warming by open-top chambers induce change in the root-associated fungal community of the arctic dwarf shrub Cassiope tetragona (Ericaceae)?. Mycorrhiza.  ISSN 0940-6360.  27(5), s 513- 524 . doi: 10.1007/s00572-017-0767-y
• Andrew, Carrie Joy; Heegaard, Einar; Halvorsen, Rune; Martinez-Pena, Fernando; Egli, Simon; Kirk, Paul M.; Bässler, Claus; Büntgen, Ulf; Aldea, Jorge; Høiland, Klaus; Boddy, Lynne & Kauserud, Håvard (2016). Climate impacts on fungal community and trait dynamics. Fungal ecology.  ISSN 1754-5048.  22, s 17- 25 . doi: 10.1016/j.funeco.2016.03.005
• Heegaard, Einar; Boddy, Lynne; Diez, Jefferey M.; Halvorsen, Rune; Kauserud, Håvard; Kuyper, Thomas W.; Bässler, Claus; Büntgen, Ulf; Gange, Alan C.; Krisai-Greilhuber, Irmgard; Andrew, Carrie Joy; Ayer, Francouis; Høiland, Klaus; Kirk, Paul M. & Egli, Simon (2016). Fine-scale spatiotemporal dynamics of fungal fruiting: prevalence, amplitude, range and continuity. Ecography.  ISSN 0906-7590.  40(8), s 947- 959 . doi: 10.1111/ecog.02256 Vis sammendrag

  Despite the critical importance of fungi as symbionts with plants, resources for animals, and drivers of ecosystem function, the spatiotemporal distributions of fungi remain poorly understood. The belowground life cycle of fungi makes it difficult to assess spatial patterns and dynamic processes even with recent molecular techniques. Here we offer an explicit spatiotemporal Bayesian inference of the drivers behind spatial distributions from investigation of a Swiss inventory of fungal fruit bodies. The unique inventory includes three temperate forest sites in which a total of 73 952 fungal fruit bodies were recorded systematically in a spatially explicit design between 1992 and 2006. Our motivation is to understand how broad-scale climate factors may influence spatiotemporal dynamics of fungal fruiting within forests, and if any such effects vary between two functional groups, ectomycorrhizal (ECM) and saprotrophic fungi. For both groups we asked: 1) how consistent are the locations of fruiting patches, the sizes of patches, the quantities of fruit bodies, and of prevalence (occupancy)? 2) Do the annual spatial characteristics of fungal fruiting change systematically over time? 3) Are spatial characteristics of fungal fruiting driven by climatic variation? We found high inter-annual continuity in fruiting for both functional groups. The saprotrophic species were characterised by small patches with variable fruit body counts. In contrast, ECM species were present in larger, but more distinctly delimited patches. The spatial characteristics of the fungal community were only indirectly influenced by climate. However, climate variability influenced overall yields and prevalence, which again links to spatial structure of fruit bodies. Both yield and prevalence were correlated with the amplitudes of occurrence and of fruit body counts, but only prevalence influenced the spatial range. Summarizing, climatic variability affects forest-stand fungal distributions via its influence on yield (amount) and prevalence (occupancy), whereas fungal life-history strategies dictate fine-scale spatial characteristics.

• Mundra, Sunil; Halvorsen, Rune; Kauserud, Håvard; Bahram, Mohammad; Tedersoo, Leho; Elberling, Bo; Cooper, Elisabeth J. & Eidesen, Pernille Bronken (2016). Ectomycorrhizal and saprotrophic fungi respond differently to long-term experimentally increased snow depth in the High Arctic. MicrobiologyOpen.  ISSN 2045-8827.  5(5), s 856- 869 . doi: 10.1002/mbo3.375 Fulltekst i vitenarkiv.
• Rämä, Teppo; Davey, Marie Louise; Nordén, Jenni; Halvorsen, Rune; Blaalid, Rakel; Mathiassen, Geir Harald; Alsos, Inger Greve & Kauserud, Håvard (2016). Fungi sailing the Arctic ocean: speciose communities in North Atlantic driftwood as revealed by high-throughput amplicon sequencing. Microbial Ecology.  ISSN 0095-3628.  72(2), s 295- 304 . doi: 10.1007/s00248-016-0778-9 Vis sammendrag

  High amounts of driftwood sail across the oceans and provide habitat for organisms tolerating the rough and saline environment. Fungi have adapted to the extremely cold and saline conditions which driftwood faces in the high north. For the first time, we applied high-throughput sequencing to fungi residing in driftwood to reveal their taxonomic richness, community composition, and ecology in the North Atlantic. Using pyrosequencing of ITS2 amplicons obtained from 49 marine logs, we found 807 fungal perational taxonomic units (OTUs) based on clustering at 97 % sequence similarity cutoff level. The phylum Ascomycota comprised 74 % of the OTUs and 20 % belonged to Basidiomycota. The richness of basidiomycetes decreased with prolonged submersion in the sea, supporting the general view of ascomycetes being more extremotolerant. However, more than one fourth of the fungal OTUs remained unassigned to any fungal class, emphasising the need for better DNA reference data from the marine habitat. Different fungal communities were detected in coniferous and deciduous logs. Our results highlight that driftwood hosts a considerably higher fungal diversity than currently known. The driftwood fungal community is not a terrestrial relic but a speciose assemblage of fungi adapted to the stressful marine environment and different kinds of wooden substrates found in it. 454 sequencing . Metabarcoding . Marine fungi . Marine wooden substrates . Diversity . Community ecology . Biosystematics

• Balasundaram, Sudhagar; Engh, Ingeborg Bjorvand; Skrede, Inger & Kauserud, Håvard (2015). How many DNA markers are needed to reveal cryptic fungal species?. Fungal Biology.  ISSN 1878-6146.  119(10), s 940- 945 . doi: 10.1016/j.funbio.2015.07.006
• Botnen, Synnøve; Kauserud, Håvard; Carlsen, Tor; Blaalid, Rakel & Høiland, Klaus (2015). Mycorrhizal fungal communities in coastal sand dunes and heaths investigated by pyrosequencing analyses. Mycorrhiza.  ISSN 0940-6360.  25(6), s 447- 456 . doi: 10.1007/s00572-014-0624-1
• Davey, Marie Louise; Blaalid, Rakel; Vik, Unni; Carlsen, Tor; Kauserud, Håvard & Eidesen, Pernille Bronken (2015). Primary succession of Bistorta vivipara (L.) Delabre (Polygonaceae) root-associated fungi mirrors plant succession in two glacial chronosequences. Environmental Microbiology.  ISSN 1462-2912.  17(8), s 2777- 2790 . doi: 10.1111/1462-2920.12770
• Mundra, Sunil; Bahram, Mohammad; Tedersoo, Leho; Kauserud, Håvard; Halvorsen, Rune & Eidesen, Pernille Bronken (2015). Temporal variation of Bistorta vivipara-associated ectomycorrhizal fungal communities in the High Arctic. Molecular Ecology.  ISSN 0962-1083.  24(24), s 6289- 6302 . doi: 10.1111/mec.13458
• Mundra, Sunil; Halvorsen, Rune; Kauserud, Håvard; Müller, Eike; Vik, Unni & Eidesen, Pernille Bronken (2015). Arctic fungal communities associated with roots of Bistorta vivipara do not respond to the same fine-scale edaphic gradients as the aboveground vegetation. New Phytologist.  ISSN 0028-646X.  205(4), s 1587- 1597 . doi: 10.1111/nph.13216
• Negård, Mariell; Uhlig, Silvio; Kauserud, Håvard; Andersen, Tom; Høiland, Klaus & Vrålstad, Trude (2015). Links between genetic groups, indole alkaloid profiles and ecology within the grass-parasitic Claviceps purpurea species complex. Toxins.  ISSN 2072-6651.  7(5), s 1431- 1456 . doi: 10.3390/toxins7051431 Fulltekst i vitenarkiv. Vis sammendrag

  The grass parasitic fungus Claviceps purpurea sensu lato produces sclerotia with toxic indole alkaloids. It constitutes several genetic groups with divergent habitat preferences that recently were delimited into separate proposed species. We aimed to 1) analyze genetic variation of C. purpurea sensu lato in Norway, 2) characterize the associated indole alkaloid profiles, and 3) explore relationships between genetics, alkaloid chemistry and ecology. Approximately 600 sclerotia from 14 different grass species were subjected to various analyses including DNA sequencing and HPLC-MS. Molecular results, supported by chemical and ecological data, revealed one new genetic group (G4) in addition to two of the three known; G1 (C. purpurea sensu stricto) and G2 (C. humidiphila). G3 (C. spartinae) was not found. G4, which was apparently con-specific with the recently described C. arundinis sp. nov, was predominantly found in very wet habitats on Molinia caerulea and infrequently in saline habitats on Leymus arenarius. Its indole-diterpene profile resembled G2, while its ergot alkaloid profile differed from G2 in high amounts of ergosedmam. In contrast to G1, indole-diterpenes were consistently present in G2 and G4. Our study supports and complements the newly proposed species delimitation of the C. purpurea complex, but challenges some species characteristics including host spectrum, habitat preferences and sclerotial floating ability.

• Veerabadran Balasundaram, Sudhagar; Engh, Ingeborg Bjorvand; Skrede, Inger & Kauserud, Håvard (2015). How many DNA markers are needed to reveal cryptic fungal species?. Fungal Biology.  ISSN 1878-6146.  119, s 940- 945 . doi: 10.1016/j.funbio.2015.07.006
• Blaalid, Rakel; Davey, Marie Louise; Kauserud, Håvard; Carlsen, Tor; Halvorsen, Rune; Høiland, Klaus & Eidesen, Pernille Bronken (2014). Arctic root-associated fungal community composition reflects environmental filtering. Molecular Ecology.  ISSN 0962-1083.  23(3), s 649- 659 . doi: 10.1111/mec.12622
• Boddy, Lynne; Büntgen, Ulf; Egli, Simon; Gange, Alan C.; Heegaard, Einar; Kirk, Paul M.; Mohammad, Aqilah & Kauserud, Håvard (2014). Climate variation effects on fungal fruiting. Fungal ecology.  ISSN 1754-5048.  10(1), s 20- 33 . doi: 10.1016/j.funeco.2013.10.006
• Botnen, Synnøve; Vik, Unni; Carlsen, Tor; Eidesen, Pernille Bronken; Davey, Marie Louise & Kauserud, Håvard (2014). Low host specificity of root-associated fungi at an Arctic site. Molecular Ecology.  ISSN 0962-1083.  23(4), s 975- 985 . doi: 10.1111/mec.12646
• Davey, Marie Louise; Kauserud, Håvard & Ohlson, Mikael (2014). Forestry impacts on the hidden fungal biodiversity associated with bryophytes. FEMS Microbiology Ecology.  ISSN 0168-6496.  90(1), s 313- 325 . doi: 10.1111/1574-6941.12386
• Maurice, Sundy; Skrede, Inger; LeFloch, Gaetan; Barbier, Georges & Kauserud, Håvard (2014). Population structure of Serpula lacrymans in Europe with an outlook to the French population. Mycologia.  ISSN 0027-5514.  106(5), s 889- 895 . doi: 10.3852/12-344
• Nilsson, R. Henrik; Hyde, Kevin D.; Pawlowska, Julia; Ryberg, Martin; Tedersoo, Leho; Aas, Anders Bjørnsgard; Alias, Siti A.; Alves, Artur; Anderson, Cajsa Lisa; Antonelli, Alexandre; Arnold, A. Elizabeth; Bahnmann, Barbara; Bahram, Mohammad; Bengtsson-Palme, Johan; Berlin, Anna; Branco, Sara; Chomnunti, Putarak; Dissanayake, Asha; Drenkhan, Rein; Friberg, Hanna; Frøslev, Tobias Guldberg; Halwachs, Bettina; Hartmann, Martin; Henricot, Beatrice; Jayawardena, Ruvishika; Jumpponen, Ari; Kauserud, Håvard; Koskela, Sonja; Kulik, Tomasz; Liimatainen, Kare; Lindahl, Björn D.; Lindner, Daniel; Liu, Jian-Kui; Maharachchikumbura, Sajeewa; Manamgoda, Dimuthu; Martinsson, Svante; Neves, Maria Alice; Niskanen, Tuula; Nylinder, Stephan; Pereira, Olinto Liparini; Pinho, Danilo Batista; Porter, Teresita M.; Queloz, Valentin; Riit, Taavi; Sánchez-García, Marisol; de Sousa, Filipe; Stefanczyk, Emil; Tadych, Mariusz; Takamatsu, Susumu; Tian, Qing; Udayanga, Dhanushka; Unterseher, Martin; Wang, Zheng; Wikee, Saowanee; Yan, Jiye; Larsson, Ellen; Larsson, Karl-Henrik; Kõljalg, Urmas & Abarenkov, Kessy (2014). Improving ITS sequence data for identification of plant pathogenic fungi. Fungal diversity.  ISSN 1560-2745.  67(1), s 11- 19 . doi: 10.1007/s13225-014-0291-8
• Rämä, Teppo; Mathiassen, Geir Harald & Kauserud, Håvard (2014). Marine fungi new to Norway, with an outlook to the overall diversity. Agarica.  ISSN 0800-1820.  35, s 35- 47 Vis sammendrag

  Marine fungi are severely understudied in Norway. In this survey we publish 17 species new to Norway and DNA reference sequences (barcodes) for seven species of obligate marine fungi. Moreover, we review previous marine mycological efforts in Norway, and compile the first check list of Norwegian marine fungi. Based on temporally and spatially unevenly distributed records, altogether 61 species of obligate marine fungi have been found in Norway since 1895, including seven species described as new to science. However, recent molecular studies on wood-inhabiting marine fungi indicate that a much greater diver¬sity exists. By examining a wide range of habitats and substrates, both with morphologi¬cal and molecular methods, we expect that thousands of fungi can be detected in Norwegian marine habitats in future. These are likely to include hundreds of obligate marine species.

• Rämä, Teppo; Nordén, Jenni; Davey, Marie; Mathiassen, Geir Harald; Spatafora, Joseph W. & Kauserud, Håvard (2014). Fungi ahoy! Diversity on marine wooden substrata in the high North. Fungal ecology.  ISSN 1754-5048.  8, s 46- 58 . doi: 10.1016/j.funeco.2013.12.002 Fulltekst i vitenarkiv.
• Bellemain, Eva; Davey, Marie; Kauserud, Håvard; Epp, Laura; Boessenkool, Sanne; Coissac, Eric; Geml, Jozsef; Edwards, Mary; Willerslev, Eske; Gussarova, Galina; Taberlet, Pierre & Brochmann, Christian (2013). Fungal palaeodiversity revealed using hight-throughput metabarcoding of ancient DNA from arctic permafrost. Environmental Microbiology.  ISSN 1462-2912.  15(4), s 1176- 1189 . doi: 10.1111/1462-2920.12020
• Blaalid, Rakel; Kumar, Surendra; Nilsson, R.H.; Abarenkov, K.; Kirk, PM & Kauserud, Håvard (2013). ITS1 versus ITS2 as DNA metabarcodes for fungi. Molecular Ecology Resources.  ISSN 1755-098X.  13(2), s 218- 224 . doi: 10.1111/1755-0998.12065
• Büntgen, Ulf; Peter, Martina; Kauserud, Håvard & Egli, Simon (2013). Unraveling environmental drivers of a recent increase in Swiss fungi fruiting. Global Change Biology.  ISSN 1354-1013.  19(9), s 2785- 2794 . doi: 10.1111/gcb.12263
• Davey, Marie; Heegaard, Einar; Halvorsen, Rune; Kauserud, Håvard & Ohlson, Mikael (2013). Amplicon-pyrosequencing-based detection of compositional shifts in bryophyte-associated fungal communities along an elevation gradient. Molecular Ecology.  ISSN 0962-1083.  22(2), s 368- 383 . doi: 10.1111/mec.12122 Vis sammendrag

  Although bryophytes are a dominant vegetation component of boreal and alpine ecosystems, little is known about their associated fungal communities. HPLC assays of ergosterol (fungal biomass) and amplicon pyrosequencing of the ITS2 region of rDNA were used to investigate how the fungal communities associated with four bryophyte species changed across an elevational gradient transitioning from conifer forest to the low-alpine. Fungal biomass and OTU richness associated with the four moss hosts did not vary significantly across the gradient (P > 0.05), and both were more strongly affected by host and tissue type. Despite largely constant levels of fungal biomass, distinct shifts in community composition of fungi associated with Hylocomium, Pleurozium and Polytrichum occurred between the elevation zones of the gradient. This likely is a result of influence on fungal communities by major environmental factors such as temperature, directly or indirectly mediated by, or interacting with, the response of other components of the vegetation (i.e. the dominant trees). Fungal communities associated with Dicranum were an exception, exhibiting spatial autocorrelation between plots, and no significant structuring by elevation. Nevertheless, the detection of distinct fungal assemblages associated with a single host growing in different elevation zones along an elevational gradient is of particular relevance in the light of the ongoing changes in vegetation patterns in boreal and alpine systems due to global climate warming.

• Davey, Marie; Heimdal, Rune; Ohlson, Mikael & Kauserud, Håvard (2013). Host- and tissue-specificity of moss-associated Galerina and Mycena determined from amplicon pyrosequencing data. Fungal ecology.  ISSN 1754-5048.  6(3), s 179- 186 . doi: 10.1016/j.funeco.2013.02.003
• Fang, Yao; Vik, Unni; Brysting, Anne Krag; Carlsen, Tor; Halvorsen, Rune & Kauserud, Håvard (2013). Substantial compositional turnover of fungal communities in an alpine ridge-to-snowbed gradient. Molecular Ecology.  ISSN 0962-1083.  22(19), s 5040- 5052 . doi: 10.1111/mec.12437
• Hyde, KD; Udayanga, D; Manamgoda, DS; Tedersoo, Leho; Larsson, Ellen; Abarenkov, Kessy; Bertrand, YJK; Oxelman, Bengt; Hartmann, M; Kauserud, Håvard; Ryberg, M; Kristiansson, Erik & Nilsson, Henrik (2013). Incorporating molecular data in fungal systematics: a guide for aspiring researchers. Current Research in Environmental & Applied Mycology.  ISSN 2229-2225.  3(1)
• Lindahl, Björn D.; Nilsson, R. Henrik; Tedersoo, Leho; Abarenkov, Kessy; Carlsen, Tor; Kjøller, Rasmus; Kõljalg, Urmas; Pennanen, Taina; Rosendahl, Søren; Stenlid, Jan & Kauserud, Håvard (2013). Fungal community analysis by high-throughput sequencing of amplified markers - a user's guide. New Phytologist.  ISSN 0028-646X.  199(1), s 288- 299 . doi: 10.1111/nph.12243
• Lindner, Daniel L.; Carlsen, Tor; Nilsson, R. Henrik; Davey, Marie; Schumacher, Trond & Kauserud, Håvard (2013). Employing 454 amplicon pyrosequencing to reveal intragenomic divergence in the internal transcribed spacer rDNA region in fungi. Ecology and Evolution.  ISSN 2045-7758.  3(6), s 1751- 1764 . doi: 10.1002/ece3.586
• Seierstad, Kristian S.; Carlsen, Tor; Sætre, Glenn-Peter; Hofton, Tom Hellik; Miettinen, Otto & Kauserud, Håvard (2013). A phylogeographic survey of a circumboreal polypore indicates introgression among ecologically differentiated cryptic lineages. Fungal ecology.  ISSN 1754-5048.  6(1), s 119- 128 . doi: 10.1016/j.funeco.2012.09.001
• Skrede, Inger; Maurice, Sandy & Kauserud, Håvard (2013). Molecular Characterization of Sexual Diversity in a Population of Serpula lacrymans, a Tetrapolar Basidiomycete. G3: Genes, Genomes, Genetics.  ISSN 2160-1836.  3(2), s 145- 152 . doi: 10.1534/g3.112.003731
• Vik, Unni; Logares, Ramiro; Blaalid, Rakel; Halvorsen, Rune; Carlsen, Tor; Bakke, Ingrid; Kolstø, Anne-Brit; Økstad, Ole Andreas Løchen & Kauserud, Håvard (2013). Different bacterial communities in ectomycorrhizae and surrounding soil. Scientific Reports.  ISSN 2045-2322.  3(347) . doi: 10.1038/srep03471 Fulltekst i vitenarkiv.
• Blaalid, Rakel; Carlsen, Tor; Kumar, Surendra; Halvorsen, Rune; Ugland, Karl Inne; Fontana, Giovanni & Kauserud, Håvard (2012). Changes in the root-associated fungal communities along a primary succession gradient analysed by 454 pyrosequencing. Molecular Ecology.  ISSN 0962-1083.  21(8), s 1897- 1908 . doi: 10.1111/j.1365-294X.2011.05214.x
• Büntgen, Ulf; Egli, Simon; Camarero, J. Julio; Fischer, Erich M.; Stobbe, Ulrich; Kauserud, Håvard; Tegel, Willy; Sproll, Ludger & Stenseth, Nils Christian (2012). Drought-induced decline in Mediterranean truffle harvest. Nature Reports: Climate Change.  ISSN 1753-9315.  2, s 827- 829
• Büntgen, Ulf; Kauserud, Håvard & Egli, Simon (2012). Linking climate variability to mushroom productivity and phenology. Frontiers in Ecology and the Environment.  ISSN 1540-9295.  10(1), s 14- 19 . doi: 10.1890/110064
• Carlsen, Tor; Bendiksby, Mika; Hofton, Tom Hellik; Reiso, Sigve; Bakkestuen, Vegar; Haugan, Reidar; Kauserud, Håvard & Timdal, Einar (2012). Species delimitation, bioclimatic range, and conservation status of the threatened lichen Fuscopannaria confusa. The Lichenologist.  ISSN 0024-2829.  44(5), s 565- 575 . doi: 10.1017/S0024282912000199
• Davey, Marie; Heegaard, Einar; Halvorsen, Rune; Ohlson, Mikael & Kauserud, Håvard (2012). Seasonal trends in the biomass and structure of bryophyte-associated fungal communities explored by 454 pyrosequencing. New Phytologist.  ISSN 0028-646X.  195(4), s 844- 856 . doi: 10.1111/j.1469-8137.2012.04215.x Vis sammendrag

  Bryophytes are a dominant vegetation component of the boreal forest, but little is known about their associated fungal communities, including seasonal variation within them.•Seasonal variation in the fungal biomass and composition of fungal communities associated with three widespread boreal bryophytes was investigated using HPLC assays of ergosterol and amplicon pyrosequencing of the internal transcribed spacer 2 (ITS2) region of rDNA.•The bryophyte phyllosphere community was dominated by Ascomycota. Fungal biomass did not decline appreciably in winter (P = 0.272). Significant host-specific patterns in seasonal variation of biomass were detected (P = 0.003). Although seasonal effects were not the primary factors structuring community composition, collection date significantly explained (P = 0.001) variation not attributed to locality, host, and tissue. Community homogenization and a reduction in turnover occurred with the onset of frost events and subzero air and soil temperatures. Fluctuations in the relative abundance of particular fungal groups seem to reflect the nature of their association with mosses, although conclusions are drawn with caution because of potential methodological bias.•The moss-associated fungal community is dynamic, exhibiting seasonal turnover in composition and relative abundance of different fungal groups, and significant fungal biomass is present year-round, suggesting a winter-active fungal community.

Se alle arbeider i Cristin

• Jacobsen, Rannveig Margrete; Sverdrup-Thygeson, Anne; Birkemoe, Tone; Kauserud, Håvard & Mundra, Sunil (2019). Experimental exclusion of invertebrates influences saprotrophic fungal community and wood decay rate in the field.
• Kjønaas, O. Janne; Bárcena, Teresa G.; Bright, Ryan M.; Hanssen, Mette; Hylen, Gro; Kauserud, Håvard; Økland, Tonje; Sunil, Mundra; Nordbakken, Jørn-Frode & Aall, Carlo (2019). The impact of increasing spruce plantation area on the carbon balance of forests in Western Norway – BalanC.
• Kjønaas, O. Janne; Bárcena, Teresa G.; Mette, Hansen; Mundra, Sunil; Kauserud, Håvard; Hylen, Gro; Økland, Tonje & Nordbakken, Jørn-Frode (2019). Effects of tree species change on soil characteristics in Western Norway - BalanC.
• Jacobsen, Rannveig Margrete; Birkemoe, Tone; Sverdrup-Thygeson, Anne; Mundra, Sunil & Kauserud, Håvard (2018). Experimental exclusion of invertebrates influences fungal community and wood decay rate.
• Jacobsen, Rannveig Margrete; Sverdrup-Thygeson, Anne; Kauserud, Håvard; Mundra, Sunil & Birkemoe, Tone (2018). Exclusion of invertebrates influences saprotrophic fungal community and wood decay rate in an experimental field study.
• Kjønaas, O. Janne; Mundra, Sunil; Bárcena, Teresa G.; Hansen, Mette; Hylen, Gro & Kauserud, Håvard (2018). How does tree species change affect forest soil C stocks, C mineralization rates, organic matter stability and microbial diversity?, In Krista Kettunen & Oili Kiikkilä (ed.),  3rd Conference on Ecology of Soil Microorganisms 2018.  LUKE.  ISBN 978-952-326-584-4.  P117.  s 134 - 134 Vis sammendrag

  Tree species change has been suggested as one of the government policies to mitigate climate change in Nor-way with the aim to increase the annual uptake of CO2 and the long-term storage of carbon (C) in forests. The strategy includes replacing native, deciduous species with fast-growing species, mainly Norway spruce. A shift in tree species is expected to affect the pools and fluxes of C in the stand as well as the microbial community. As part of the BalanC project, we assess C storage related to shift in tree species cover in western Norway and whether a corresponding shift in soil microbial communities are happening. The study aim at integrating results on soil respiration, C mineralization, soil stability, diversity of bacteria, fungi and micro-eukaryotes, soil nutrient pools, litter inputs and edaphic factors at the stand level in order to identify key drivers for changes in the soil C stocks. Fifteen paired plots of native birch and planted Norway spruce at five locations were sampled. Prelimi-nary results suggests a redistribution of C from the mineral soil to the forest floor in the spruce stands, with minor changes in the total soil C pools over the 45-60 years since the tree species change. The in situ soil respi-ration and heterothropic respiration, as well as C mineralization rates, were higher in birch than in spruce stands. Differences in C mineralization rates attenuate with depth between forest types. The microbial com-munities of the three organismal groups were all strongly structured along the vertical depth.

• Kjønaas, O. Janne; Mundra, Sunil; Bárcena, Teresa G.; Hansen, Mette; Hylen, Gro & Kauserud, Håvard (2018). How does tree species change affect forest soil C stocks, C mineralization rates, organic matter stability and microbial diversity?.
• Mundra, Sunil; Morgado, Luis Neves; Kjønaas, O. Janne & Kauserud, Håvard (2018). Community of bacteria, fungi and micro-eukaryotes structured along soil forest stratification..
• Mundra, Sunil; Morgado, Luis Neves; Kjønaas, O. Janne & Kauserud, Håvard (2018). Soil depth matters: Bacteria, fungi and micro-eukaryotes are all strongly structured by soil depth, In Krista Kettunen & Oili Kiikkilä (ed.),  3rd Conference on Ecology of Soil Microorganisms 2018.  LUKE.  ISBN 978-952-326-584-4.  P164.  s 157 - 157 Vis sammendrag

  The boreal forest is a key ecosystem for global C sequestration and storage. Microorganisms in soil have crucial functions in regulating these processes. Fungi are typically sharply structured with soil depth, but we largely lack such information for other microorganism, including bacteria and other micro-eukaryotes. To improve our knowledge of how different microorganisms are structured vertically and how they might interact, we investi-gated the communities of bacteria, fungi and micro-eukaryotes in four different soil horizons in natural birch forests in Western Norway. The communities of all three organismal groups were strongly structured along the vertical depth. Our results support the hypothesis that natural decrease in nutrient availability and pH differ-ences between organic and mineral horizons affect the distribution of soil microorganisms. Proteobacteria, Actinobacteria and Planctomycetes dominated in the uppermost organic layer while Acidobacteria and Firmicu-tes in mineral layers. Proportionally, fungi dominated in mineral layers whereas other micro-eukaryotes (Meta-zoa, Apicomplexa, Conosa, Ochrophyta and Chlorophyta) in organic layers. Ascomycota were relatively more abundant in mineral layers compared to Basidiomycota and Cryptomycota. Nematoda, Annelida and Arthropo-da showed decreasing trends with depth. Furthermore, different optima in the depth distribution of ectomy-corrhizal and saprotrophic genera was observed, supporting the view that different genera are adapted to different niches along the soil depth gradient. Network analyses will be used to infer tentative biotic interac-tions between the microbial groups and how this varies with soil depth.

• Mundra, Sunil; Morgado, Luis Neves; Kjønaas, O. Janne & Kauserud, Håvard (2018). Soil depth matters: Bacteria, fungi and micro-eukaryotes are strongly structured by soil Depth..
• Skrede, Inger; Hess, Jaqueline; Eastwood, Daniel C. & Kauserud, Håvard (2018). Evolutionary necessities for invading buildings, comparative and population genomic analyses of the dry rot fungus.
• Skrede, Inger; Hess, Jaqueline; Sønstebø, Jørn Henrik; Maurice, Sundy Ursula Mary Jane; Eastwood, Daniel C. & Kauserud, Håvard (2018). How to decompose a house? Comparative and population genomic analyses of the dry rot fungus.
• Tonjer, Lea-Rebekka; Thoen, Ella; Morgado, Luis Neves; Mundra, Sunil; Nybakken, Line; Bryn, Anders & Kauserud, Håvard (2018). Changes in the soil fungal community across the mountain birch tree line ecotone.
• Vollsnes, Ane Victoria; Eriksen, Aud Berglen; Berntsen, Terje Koren; Kauserud, Håvard; Büker, Patrick; Emberson, Lisa D. & Stordal, Frode (2018). The double punch: ozone and climate stresses to sub-Arctic vegetation.
• Vollsnes, Ane Victoria; Eriksen, Aud Berglen; Büker, Patrick; Kauserud, Håvard; Falk, Stefanie & Stordal, Frode (2018). Ozone stress on sub-Arctic tundra vegetation: ozone exposure experiments with daylength manipulation..
• Vollsnes, Ane Victoria; Eriksen, Aud Berglen; Falk, Stefanie; Berntsen, Terje Koren; Kauserud, Håvard; Emberson, Lisa D. & Stordal, Frode (2018). Project The double punch: ozone and climate stresses on vegetation.
• Vollsnes, Ane Victoria; Eriksen, Aud Berglen; Kauserud, Håvard; Berntsen, Terje Koren & Stordal, Frode (2018). The double punch: ozone and climate stresses on vegetation.
• Skrede, Inger; Hess, Jaqueline; Balasundaram, Sudhagar; Högberg, Nils; Maurice, Sundy Ursula Mary Jane; Kohler, Annegret; Martin, Francis; Eastwood, Daniel C. & Kauserud, Håvard (2017). Evolutionary necessities for invading buildings, comparative and population genomic analyses in the dry rot fungus.
• Stordal, Frode; Tang, Hui; Berntsen, Terje Koren; Büker, Patrick; Vollsnes, Ane Victoria; Eriksen, Aud Berglen & Kauserud, Håvard (2017). Modelling combined effects of ozone and climate stresses on Arctic and boreal species.
• Eidesen, Pernille Bronken; Mundra, Sunil; Botnen, Synnøve Smebye; Davey, Marie Louise; Lorberau, Kelsey & Kauserud, Håvard (2016). Spatial diversity and community composition of root associated fungi in the High Arctic archipelago Svalbard - environmental influence is scale dependent.
• Hess, Jaqueline; Balasundaram, Sudhagar; Eastwood, Daniel C.; Durling, Mikael Brandström; Fossdal, Carl Gunnar; Högberg, Nils; Kauserud, Håvard & Skrede, Inger (2016). Exploring specialization in wood decay mechanisms in the harmful house-invader Serpula lacrymans using an evolutionary transcriptomics approach.
• Jacobsen, Rannveig M; Birkemoe, Tone; Sverdrup-Thygeson, Anne; Kauserud, Håvard & Botnen, Synnøve Smebye (2016). The potential of insects to act as spore vectors.
• Rämä, Teppo; Davey, Marie Louise; Nordén, Jenni; Halvorsen, Rune; Blaalid, Rakel; Mathiassen, Geir Harald; Alsos, Inger Greve & Kauserud, Håvard (2016). High-throughput amplicon sequencing reveals high fungal diversity in North Atlantic driftwood.
• Skrede, Inger; Hess, Jaqueline; Balasundaram, Sudhagar; Kauserud, Håvard; Eastwood, Daniel C.; Boddy, Lynne M; Durling, Mikael Brandström; Högberg, Nils & Grigoriev, Igor V. (2016). The fungus that came in from the cold: Dry rots pre-adapted ability to invade buildings.
• Skrede, Inger; Hess, Jaqueline; Balasundaram, Sudhagar; Kauserud, Håvard; Eastwood, Daniel C.; Högberg, Nils; Kohler, Annegret; Murat, Claude; Durling, Mikael Brandström & Martin, Francis (2016). Invasiveness of the harmful house-invader Serpula lacrymans – population genomics of the Japanese and European populations.
• Skrede, Inger; Hess, Jaqueline; Balasundaram, Sudhagar; Eastwood, D; Kohler, Annegret; Murat, Claude; Barry, Dominique; Durling, Mikael Brandström; Högberg, Nils; Kauserud, Håvard & Martin, Francis (2015). Invasiveness of the harmful house decomposer Serpula lacrymans - population genomic approaches.
• Eidesen, Pernille Bronken; Mundra, Sunil; Davey, Marie L.; Nadeau, Courtney & Kauserud, Håvard (2014). Plant-fungi interactions in Svalbard.
• Eidesen, Pernille Bronken; Mundra, Sunil & Kauserud, Håvard (2014). Can host genotype influence richness and composition of fungal root-symbionts in Bistorta vivipara in high-arctic tundra?.
• Negård, Mariell; Uhlig, Silvio; Kauserud, Håvard; Høiland, Klaus; Andersen, Tom & Vrålstad, Trude (2014). Indole alkaloid profiles in ergot (Claviceps purpurea): Is there a link between chemotype, genetic group and ecology?.
• Vrålstad, Trude; Negård, Mariell; Uhlig, Silvio; Andersen, Tom; Høiland, Klaus & Kauserud, Håvard (2014). Links between genetics, indole alkaloid chemistry and ecology within the grass-parasitic Claviceps purpurea species complex. Vis sammendrag

  Claviceps purpurea produces sclerotia with toxic indole alkaloids that replace the grass host grains. Three genetic groups (G1-G3) with divergent habitat preferences and alkaloid chemistry are known from studies mainly covering America and Western Europe. We aimed to analyse the genetic variation in C. purpurea in Norway, characterize the indole alkaloid profiles within each genetic group, and explore the relationships between genetics, alkaloid chemistry and ecology. Sclerotia (~600) from 14 grass species were subjected to a floating test with subsequent DNA sequencing (ITS rDNA&beta tubulin) and indole alkaloid profiling (HPLC-MS). Phylogenetic analyses and haplotype networks supported the three known (G1-G3) and one new (G4) genetic groups of C. purpurea. This gained additional support from chemical and ecological data. The G4 group, predominantly found in very wet habitats on Molinia caerulea and infrequently in saline habitats on Leymus arenarius, produced consistently floating sclerotia. Its indolediterpenoid profile resembled G2, but differed in high amounts of ergopeptamergosedmam, the lactam congener of ergosedmine. Indolediterpenoids were consistently present in G2 and G4, while merely absent in G1. The G3 group was absent in our study, but G1 and G2 occurred on numerous grass species in different habitats (wet, dry and saline). Co-occurrence of up to three genetic groups on the same host within one plot was observed. Our study supports that the alkaloid chemistry in C. purpurea is a function of the genetic groups. Further, the co-occurrence suggests completed speciation in several genetic groups (ecotypes) within the C. purpurea complex

• Kauserud, Håvard; Heegaard, Einar; Büntgen, Ulf; Halvorsen, Rune; Egli, Simon; Senn-Irlet, Beatrice; Krisai-Greilhuber, Irmgard; Dämon, Wolfgang; Nordén, Jenni; Høiland, Klaus; Kirk, Paul M.; Semenov, Mikhail A.; Stenseth, Nils Christian & Boddy, Lynne (2013). Reply to Gange et al.: Climate-driven changes in the fungal fruiting season in the United Kingdom. Proceedings of the National Academy of Sciences of the United States of America.  ISSN 0027-8424.  110(5), s E335- E335 . doi: 10.1073/pnas.1221131110
• Rämä, Teppo; Nordén, Jenni; Davey, Marie; Mathiassen, Geir Harald; Spatafora, JW & Kauserud, Håvard (2013). Diversity of wood-inhabiting marine fungi in the high North. Vis sammendrag

  Abstract - Marine fungi are severely understudied in Norway and in the Arctic. In this study, fungi were isolated from small pieces of 50 shore-cast and sea-floor logs incubated on agar plates, and were identified based on ITS and LSU sequences. The aim was to explore the taxonomic, phylogenetic and ecological diversity of wood-inhabiting marine fungi using a culturing approach and study the factors shaping fungal communities along the long coastline of mainland Northern Norway. Altogether, 577 pure cultures were included, which clustered into 147 operational taxonomic units (OTUs) using 97 % ITS sequence similarity threshold. More than half of the OTUs were singletons. Phylum Ascomycota was represented by 111 OTUs in 14 orders, Basidiomycota by 9 and Mucoromycotina by 5 OTUs. The most abundant orders were Hypocreales, Helotiales, Pleosporales, Lulworthiales and Eurotiales. The most abundant and third most abundant OTUs belonged to the genus Cadophora (Helotiales) which is rarely reported from marine environments. Known marine fungi occurred in every phylum detected, however almost half of the OTUs were considered non-marine. The Norwegian Sea in the west and the Barents Sea in the east each hosted different fungal communities and shared only 20 percent of their OTUs. Geography and ecological parameters shape the mycota in driftwood. Rarefaction curves showed that only part of the total fungal community was recovered, and it is obvious that more work and effective next-generation sequencing methods are needed for characterizing the total fungal diversity and to better understand the factors shaping the marine wood-inhabiting fungal communities.

• Vrålstad, Trude; Negård, Mariell; Uhlig, Silvio; Kauserud, Håvard; Høiland, Klaus & Andersen, Tom (2013). INDOLE-ALKALOID PROFILES IN NORWEGIAN CLAVICEPS PURPUREA POPULATIONS – RELATIONSHIPS BETWEEN CHEMORACES, GENETIC GROUPS, AND ECOLOGY. Vis sammendrag

  Claviceps purpurea is a phytopathogenic ascomycete that parasitizes various grasses, most notably rye. Instead of a grain the infected host plant produces a fungal sclerotium in the autumn, containing toxic indole-alkaloids hazardous to animals and humans. Previously, three different genetic groups (G1-G3) with divergent habitat preferences and alkaloid chemistry have been detected, often referred to as C. purpurea ecotypes and chemoraces. The main aims of this study were to (1) analyse the genetic variation in C. purpurea in Norway, (2) characterise the indole-alkaloid profiles in relation to genetic groups, and (3) reveal the relationships between genetic groups, chemoraces and ecology. In total, 596 sclerotia from 14 different grass species were subjected to various analyses, including a sclerotial floating test, genetic analyses from which rDNA ITS and partial beta tubulin sequences were generated, and mass peaks of indole-alkaloids that were measured using HPLC-MS. After the floating test, all sclerotia were cut in halves in order to analyse one half genetically and one half chemically. Phylogenetic analyses and haplotype networks of genetic data supported three known (G1-G3) and one new (G4) genetic groups of C. purpurea, of which G1, G2 and G4 was present in Norway while G3 was absent. The new G4 group was supported also from chemical and ecological data. G4 produced sclerotia that were consistently floating, and was predominantly found in very wet habitats on Molinia caerulea, and occasionally also in saline habitats on Leymus arenarius. The G4 indole-alkaloid profile resembled that of G2, but differed with high amounts of the ergopeptam ergosedmam, a lactam congener of ergosedmine. Previously, G2 has been referred to as a chemorace based on its sole production of ergosine and ergocristine. The G2 sclerotia analysed in this study contained also mainly ergocristine, but in addition similar relative amounts of ergocryptine, and also lesser amounts of the other ergot alkaloids. A consistent presence of indole-diterpenoids in sclerotia from the G2 and G4 genetic groups was demonstrated, while these compounds with few exceptions were absent in the G1 genetic group. This study support that alkaloid chemistry is a function of the genetic groups, and that the indole-alkaloids profiles of C. purpurea sclerotia can be used to assign them to a specific genetic group. While G1 and G2 were found on numerous host plants and in different habitats, G3 and G4 seem to be more host and habitat specific. Co-occurrence of up to three genetic groups on the same host plant within the same habitat was observed. Thus, the results provided here suggest that the four groups G1-G4 in the C. purpurea complex represent four biological (cryptic) species rather than only ecotypes.

• Büntgen, Ulf; Egli, Simon; Camarero, J. Julio; Fischer, Erich M.; Stobbe, Ulrich; Kauserud, Håvard; Tegel, Willy; Sproll, Ludger & Stenseth, Nils Christian (2012). CORRESPONDENCE: Drought-induced decline in Mediterranean truffle harvest. Nature Climate Change.  ISSN 1758-678X.  2(12), s 827- 829
• Carlsen, Tor; Aas, Anders Bjørnsgard; Lindner, D; Vrålstad, Trude; Schumacher, Trond & Kauserud, Håvard (2012). Don't make a mista(g)ke: is tag switching an overlooked source of error in amplicon pyrosequencing studies?. Fungal ecology.  ISSN 1754-5048.  5(6), s 747- 749 . doi: 10.1016/j.funeco.2012.06.003 Vis sammendrag

  High throughput sequencing has become a powerful tool for fungal ecologists to explore the diversity and composition of fungal communities. However, various biases and errors are associated with the new sequencing techniques that must be handled properly. We here provide evidence for a source of error that has not yet been taken into account. During amplicon pyrosequencing we incorporate tags in both ends of the amplicons, which allows us to check for tag coherence after sequencing. In several studies we have observed that a small proportion of the resulting sequences possess novel tag combinations. Our observations cannot be explained by primer contamination or PCR chimaeras. This indicates that some DNA fragments switch tags during laboratory setup. If not controlled for, this will cause numerous false positives in downstream analyses. In most amplicon pyrosequencing studies of fungal communities, amplicons are typically tagged in one end only. We suggest that amplicons should be tagged in both ends before pyrosequencing to control for tag switching.

• Davey, Marie; Heimdal, Rune; Ohlson, Mikael & Kauserud, Håvard (2012). Host and tissue specificities in Galerina and Mycena species associated with boreal forest mosses revealed by data-mining of amplicon pyrosequencing fungal inventories.

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