Lepa juurtel ektomükoriisat moodustavate seente biogeograafia ja ökoloogia

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Antud doktoritöö adresseerib lepaga koos kasvavate ektomükoriissete seente biogeograafiat ja ökoloogiat. Oma laialdase leviku ja spetsiifilise seenestiku tõttu sobivad lepp ja tema juuresümbiondid heaks mudeliks uurimaks mitmesuguseid ökoloogilisi seaduspärasusi mis puudutavad ektomükoriiseid seeni ja neid mõjutavaid tegureid nii regionaalses kui globaalses skaalas. Oma töös testisin järgnevaid põhilisi hüpoteese: 1) globaalses skaalas mõjutab lepa seenekoosluse struktuuri enim peremeesliikide fülogeneetilised distantsid; 2) regionaalses skaalas mõjutab lepa juurtel ektomükoriisat moodustavate seente koosluse struktuuri mulla koostis, eriti pH ja fosfor; 3) globaalses skaalas on lepaga seotud ektomükoriisa seente liigiline mitmekesisus määratud aasta keskmise temperatuuri ja sademete hulga poolt; 4) lepaga seotud ektomükoriisa seente biogeograafia peegeldab peremehe globaalseid levikuteid. Selgus, et globaalses skaalas mõjutavad peremeesliikide fülogeneetilised distantsid 43% ulatuses lepaga seotud ektomükoriissete seente koosluse struktuuri. Ruumiline paiknevus mõjutab seenekoosluse struktuuri 10% ulatuses ning mulla pH–l ja aasta keskmisel temperatuuril on marginaalne mõju. Seevastu regionaalses skaalas, määravad mulla pH ja orgaanilise aine sisaldus, enim seenekoosluse struktuuri. Varasemad uuringud on leidnud, et peamised mõjutegurid, mis määravad ektomükoriissete seente liigirikkust globaalses skaalas, on aasta keskmine temperatuur ja sademete hulk. Meie uuringust selgus üllatuslikult, et lepaga seotud ektomükoriissete seente liigirikkus on enim mõjutatud ja positiivses seoses mulla kaltsiumisisaldusega. Samas leidis kinnitust negatiivne seos ektomükoriisa liigirikkuse ja sademete hulga vahel. Sarnaselt globaalsele mustrile, oli ka regionaalses skaalas liigirikkus negatiivses seoses mulla veesisaldusega. Võrreldes lepaga seotud seenekoosluste liigist ja arvulist koosseisu erinevate mandrite ja piirkondade vahel selgus, et tõenäoliselt on Beringia maismaasild olnud põhiline lepa levikutee Euraasia ja Ameerika vahel. Põhja ja Lõuna Euroopa seenekooslused osutusid väga sarnaseks, mis tõenäoliselt tuleneb jääaja järgsest lepa ja tema juursümbiontide levikust põhja suunas lõunapoolsetest refuugiumidest.This thesis examines the community structure, species richness and biogeography of Alnus-associated ectomycorrhizal (EcM) fungi from local to global scales. Alnus has a wide geographical range of distribution and low richness of fungal symbionts, which enables to address the following hypothesis: 1) host species and their phylogenetic relationships account for the strongest predictor of EcM fungal community composition at the intrageneric level at the global scale; 2) at regional scale, soil conditions such as pH and phosphorus concentration drive the EcM community structure rather than geographical and host genetic distance; 3) at global scale, Alnus-associated EcM fungal species richness is largely determined by the mean annual temperature and precipitation; 4) global biogeography of Alnus EcM communities reflects ancient migration routes of host. The main results and conclusions are the following 1) phylogenetic relations among hosts account for strongest predictor of EcM community structure, while geographical and edaphic variables have a relatively low impact at the global scale; 2) at the regional scale edaphic variables were the dominant determinants of EcM fungal community structure; 3) soil calcium accounted for the key determinant of Alnus-associated EcM fungal species richness at the global scale, while soil humidity was the most influential at the local and regional scales; 4) Beringia is likely to be primary migration route of Alnus from Eurasia to America rather than North Atlantic land bridge 5) high similarity between North and South Europe probably results from recent post-glacial recolonisation

Tree diversity and species identity effects on soil fungi, protists and animals are context dependent

Plant species richness and the presence of certain influential species (sampling effect) drive the stability and functionality of ecosystems as well as primary production and biomass of consumers. However, little is known about these floristic effects on richness and community composition of soil biota in forest habitats owing to methodological constraints. We developed a DNA metabarcoding approach to identify the major eukaryote groups directly from soil with roughly species-level resolution. Using this method, we examined the effects of tree diversity and individual tree species on soil microbial biomass and taxonomic richness of soil biota in two experimental study systems in Finland and Estonia and accounted for edaphic variables and spatial autocorrelation. Our analyses revealed that the effects of tree diversity and individual species on soil biota are largely context dependent. Multiple regression and structural equation modelling suggested that biomass, soil pH, nutrients and tree species directly affect richness of different taxonomic groups. The community composition of most soil organisms was strongly correlated due to similar response to environmental predictors rather than causal relationships. On a local scale, soil resources and tree species have stronger effect on diversity of soil biota than tree species richness per se

Global diversity and distribution of nitrogen-fixing bacteria in the soil

Our knowledge of microbial biogeography has advanced in recent years, yet we lack knowledge of the global diversity of some important functional groups. Here, we used environmental DNA from 327 globally collected soil samples to investigate the biodiversity patterns of nitrogen-fixing bacteria by focusing on the nifH gene but also amplifying the general prokaryotic 16S SSU region. Globally, N-fixing prokaryotic communities are driven mainly by climatic conditions, with most groups being positively correlated with stable hot or seasonally humid climates. Among soil parameters, pH, but also soil N content were most often shown to correlate with the diversity of N-fixer groups. However, specific groups of N-fixing prokaryotes show contrasting responses to the same variables, notably in Cyanobacteria that were negatively correlated with stable hot climates, and showed a U-shaped correlation with soil pH, contrary to other N-fixers. Also, the non-N-fixing prokaryotic community composition was differentially correlated with the diversity and abundance of N-fixer groups, showing the often-neglected impact of biotic interactions among bacteria

Global patterns in endemicity and vulnerability of soil fungi

Fungi are highly diverse organisms, which provide multiple ecosystem services. However, compared with charismatic animals and plants, the distribution patterns and conservation needs of fungi have been little explored. Here, we examined endemicity patterns, global change vulnerability and conservation priority areas for functional groups of soil fungi based on six global surveys using a high-resolution, long-read metabarcoding approach. We found that the endemicity of all fungi and most functional groups peaks in tropical habitats, including Amazonia, Yucatan, West-Central Africa, Sri Lanka, and New Caledonia, with a negligible island effect compared with plants and animals. We also found that fungi are predominantly vulnerable to drought, heat and land-cover change, particularly in dry tropical regions with high human population density. Fungal conservation areas of highest priority include herbaceous wetlands, tropical forests, and woodlands. We stress that more attention should be focused on the conservation of fungi, especially root symbiotic arbuscular mycorrhizal and ectomycorrhizal fungi in tropical regions as well as unicellular early-diverging groups and macrofungi in general. Given the low overlap between the endemicity of fungi and macroorganisms, but high conservation needs in both groups, detailed analyses on distribution and conservation requirements are warranted for other microorganisms and soil organisms

FungalTraits:A user-friendly traits database of fungi and fungus-like stramenopiles

The cryptic lifestyle of most fungi necessitates molecular identification of the guild in environmental studies. Over the past decades, rapid development and affordability of molecular tools have tremendously improved insights of the fungal diversity in all ecosystems and habitats. Yet, in spite of the progress of molecular methods, knowledge about functional properties of the fungal taxa is vague and interpretation of environmental studies in an ecologically meaningful manner remains challenging. In order to facilitate functional assignments and ecological interpretation of environmental studies we introduce a user friendly traits and character database FungalTraits operating at genus and species hypothesis levels. Combining the information from previous efforts such as FUNGuild and Fun(Fun) together with involvement of expert knowledge, we reannotated 10,210 and 151 fungal and Stramenopila genera, respectively. This resulted in a stand-alone spreadsheet dataset covering 17 lifestyle related traits of fungal and Stramenopila genera, designed for rapid functional assignments of environmental studies. In order to assign the trait states to fungal species hypotheses, the scientific community of experts manually categorised and assigned available trait information to 697,413 fungal ITS sequences. On the basis of those sequences we were able to summarise trait and host information into 92,623 fungal species hypotheses at 1% dissimilarity threshold

Connecting the multiple dimensions of global soil fungal diversity

How the multiple facets of soil fungal diversity vary worldwide remains virtually unknown, hindering the management of this essential species-rich group. By sequencing high-resolution DNA markers in over 4000 topsoil samples from natural and human-altered ecosystems across all continents, we illustrate the distributions and drivers of different levels of taxonomic and phylogenetic diversity of fungi and their ecological groups. We show the impact of precipitation and temperature interactions on local fungal species richness (alpha diversity) across different climates. Our findings reveal how temperature drives fungal compositional turnover (beta diversity) and phylogenetic diversity, linking them with regional species richness (gamma diversity). We integrate fungi into the principles of global biodiversity distribution and present detailed maps for biodiversity conservation and modeling of global ecological processes

Correction to: FungalTraits: a user friendly traits database of fungi and fungus-like stramenopiles (Fungal Diversity, (2020), 105, 1, (1-16), 10.1007/s13225-020-00466-2)

There were errors in the name of author László G. Nagy and in affiliation no. 31 in the original publication. The original article has been corrected

FungalTraits: a user-friendly traits database of fungi and fungus-like stramenopiles

The cryptic lifestyle of most fungi necessitates molecular identification of the guild in environmental studies. Over the past decades, rapid development and affordability of molecular tools have tremendously improved insights of the fungal diversity in all ecosystems and habitats. Yet, in spite of the progress of molecular methods, knowledge about functional properties of the fungal taxa is vague and interpretation of environmental studies in an ecologically meaningful manner remains challenging. In order to facilitate functional assignments and ecological interpretation of environmental studies we introduce a user friendly traits and character database FungalTraits operating at genus and species hypothesis levels. Combining the information from previous efforts such as FUNGuild and FunFun together with involvement of expert knowledge, we reannotated 10,210 and 151 fungal and Stramenopila genera, respectively. This resulted in a stand-alone spreadsheet dataset covering 17 lifestyle related traits of fungal and Stramenopila genera, designed for rapid functional assignments of environmental studies. In order to assign the trait states to fungal species hypotheses, the scientific community of experts manually categorised and assigned available trait information to 697,413 fungal ITS sequences. On the basis of those sequences we were able to summarise trait and host information into 92,623 fungal species hypotheses at 1% dissimilarity threshold

LEHO TEDERSOO,* † MOHAMMAD BAHRAM, * MÄRT TOOTS, * ABDALA G. DIÉDHIOU, ‡ TERRY

Towards global patterns in the diversity and community structure of ectomycorrhizal fung

Towards global patterns in the diversity and community structure of ectomycorrhizal fungi

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.Fil: Tedersoo, Leho. Tartu University. Institute of Ecology and Earth Sciences; Estonia. Natural History Museum of Tartu University; EstoniaFil: Bahram, Mohammad. Tartu University. Institute of Ecology and Earth Sciences; EstoniaFil: Toots, Märt. Tartu University. Institute of Ecology and Earth Sciences; Estados UnidosFil: Diédhiou, Abdala G.. Université Cheikh Anta Diop. Département de Biologie Végétale. Laboratoire Commun de Microbiologie; SenegalFil: Henkel, Terry W.. Humboldt State University. Department of Biological Sciences; Estados UnidosFil: Kjøller, Rasmus. University of Copenhagen. Biological Institute; DinamarcaFil: Morris, Melissa H.. University of California. Department of Land, Air and Water Resources; Estados UnidosFil: Nara, Kazuhide. The University of Tokyo. Department of Natural Environmental Studies; JapónFil: Nouhra, Eduardo Ramon. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Peay, Kabir. University of Minnesota. Department of Plant Pathology; Estados UnidosFil: Polme, Sergei. Tartu University. Institute of Ecology and Earth Sciences; Estonia. Natural History Museum of Tartu University; EstoniaFil: Ryberg, Martin. University of Tennessee. Department of Ecology and Evolutionary Biology; Estados UnidosFil: Smith, Matthew. Duke University. Department of Biology; Reino Unido. University of Florida. Department of Plant Pathology; Estados UnidosFil: Koljalg, Urmas. Tartu University. Institute of Ecology and Earth Sciences; Estonia. Natural History Museum of Tartu University; Estoni