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Tropical mountain forests are hotspots of biodiversity that are widely threatened by human population pressure and climate change. However, the cryptogamic species richness of many tropical mountain regions is insufficiently known, the poorly understood biodiversity of tropical African lichens being a prime example. To study the diversity of the genus Peltigera (Ascomycota, Lecanoromycetes) in East Africa, we studied lichens in a wide range of habitats on the slopes of Mt Kilimanjaro in Tanzania. Ranging from savannah to alpine heath vegetation and from natural forests to agricultural environments, 13 habitat types were sampled for lichens, which were then identified based on the nuITS genetic marker and morphology. We found eight Peltigera species on the slopes of Mt Kilimanjaro, including P. alkalicola sp. nov., P. dolichorhiza, P. polydactyloides, P. praetextata, P. rufescentiformis, P. seneca, P. sorediifera and P. ulcerata. Peltigera is most common and species-rich in the subalpine Erica forest zone, and four of the eight detected species were present only in the subalpine and alpine vegetation zones. Peltigera alkalicola was identified as a previously undescribed species, growing on trachybasaltic lava in the subalpine and alpine zones of Mt Kilimanjaro. The species resembles P. lepidophora but differs by possessing smaller thalli and peltate isidia that are distinctly dark on the lighter, tomentose lamina. Based on data from the NCBI GenBank, P. alkalicola probably also occurs in Alaska (USA) and Ningxia (China). This suggests that even though the species might generally be rare, it may have a global distribution in extreme mountain environments. For the first time, we report P. sorediifera from Tanzania and P. seneca from Africa.

International audience; Amber is renowned for the exceptional preservation state of its inclusions, allowing detailed morphological analysis and providing relevant environmental, palaeoecological, geographical, and geological information. Amber deposits predominantly known from North America, Europe, and Asia, are considered to be rare on the continents that formed Gondwana. The recent discovery of fossiliferous amber deposits in Ethiopia therefore provides an inimitable opportunity to close gaps in the fossil record of African terrestrial biota, and to study organisms otherwise rare in the fossil record. Here we show that diverse cryptogams are preserved in highest fidelity in Miocene Ethiopian amber. We describe gametophyte fragments of four liverworts: Thysananthus aethiopicus sp. nov. (Porellales, Lejeuneaceae), Lejeunea abyssinicoides sp. nov. (Porellales, Lejeuneaceae), Frullania shewanensis sp. nov. (Porellales, Frullaniaceae), and Frullania palaeoafricana sp. nov. (Porellales, Frullaniaceae). Furthermore, we describe a pleurocarpous moss of the extant genus Isopterygium (Hypnales, Pylaisiadelphaceae) and a lichen representing the order Lecanorales. These new specimens represent the first amber fossils of liverworts, mosses, and lichens from the African continent and render Ethiopian amber one of the few worldwide amber deposits preserving bryophytes (mosses and liverworts) or lichens. Fossil species of Thysananthus were recorded in Eocene Baltic and Oligocene Bitterfeld as well as Miocene Dominican and probably also Miocene Mexican ambers. Fossils which can unequivocally be assigned to Lejeunea have only been found in Dominican amber, so far. Neotropical ambers contain only one taxon of Frullania to date, while the genus is most diverse in Baltic, Bitterfeld, and Rovno ambers, formed in temperate regions. The new fossils support a tropical to subtropical origin of Ethiopian amber. The new African liverwort fossils are included in an updated list of leafy liverworts described from worldwide Cenozoic ambers to date.

Bird‐mediated dispersal is presumed to be important in the dissemination of many different types of organisms, but concrete evidence remains scarce. This is especially true for biota producing microscopic propagules. Tree‐dwelling birds, such as woodpeckers, would seem to represent ideal dispersal vectors for organisms growing on standing tree trunks such as epiphytic lichens and fungi. Here, we utilize bird natural history collections as a novel source of data for studying dispersal ecology of plants, fungi, and microorganisms. We screened freshly preserved specimens of three Finnish woodpecker species for microscopic propagules. Samples were taken from bird feet, and chest and tail feathers. Propagules were extracted using a sonication–centrifugation protocol, and the material obtained was studied using light microscopy. Diverse biological material was recovered from all specimens of all bird species, from all positions sampled. Most abundant categories of discovered biological material included bryophyte fragments, fungal spores, and vegetative propagules of lichens. Also, freshwater diatoms, bryophyte spores, algal cells, testate amebae, rotifers, nematodes, pollen, and insect scales were identified. The method developed here is applicable to living specimens as well, making it a versatile tool for further research. Our findings highlight the potential of bird‐mediated dispersal for diverse organisms and showcase the use of natural history collections in ecological research., Woodpeckers are ideal candidates for bird‐mediated dispersal for a diverse set of organisms, especially epiphytes. We report high loads of diverse biological propagules extracted from feathers and feet of woodpecker specimens from natural history collections. The study highlights the potential of birds as dispersal vectors of lichens, fungi, bryophytes, and more.

Fruticose lichens of the genus Usnea Dill. ex Adans. (Parmeliaceae), generally known as beard lichens, are among the most iconic epiphytic lichens in modern forest ecosystems. Many of the c. 350 currently recognized species are widely distributed and have been used as bioindicators in air pollution studies. Here we demonstrate that usneoid lichens were present in the Palaeogene amber forests of Europe. Based on general morphology and annular cortical fragmentation, one fossil from Baltic amber can be assigned to the extant genus Usnea. The unique type of cortical cracking indirectly demonstrates the presence of a central cord that keeps the branch intact even when its cortex is split into vertebrae-like segments. This evolutionary innovation has remained unchanged since the Palaeogene, contributing to the considerable ecological flexibility that allows Usnea species to flourish in a wide variety of ecosystems and climate regimes. The fossil sets the minimum age for Usnea to 34 million years (late Eocene). While the other similar fossils from Baltic and Bitterfeld ambers cannot be definitely assigned to the same genus, they underline the diversity of pendant lichens in Palaeogene amber forests.

Tropical mountains and especially their forests are hot spots of biodiversity threatened by human population pressure and climate change. The diversity of lichens in tropical Africa is especially poorly known. Here we use the mtSSU and nuITS molecular markers together with morphology and ecology to assess Leptogium (Peltigerales, Ascomycota) diversity in the tropical mountains of Taita Hills and Mt. Kasigau in Kenya and Mt. Kilimanjaro in Tanzania. The sampled habitats cover a wide range of ecosystems from savanna to alpine heath vegetation and from relatively natural forests to agricultural environments and plantation forests. We demonstrate that Leptogium diversity in Africa is much higher than previously known and provide preliminary data on over 70 putative species, including nine established species previously known from the area and over 60 phylogenetically, morphologically, and/or ecologically defined Operational Taxonomic Units (OTUs). Many traditional species concepts are shown to represent morphotypes comprised of several taxa. Many of the species were only found from specific ecosystems and/or restricted habitats and are thus threatened by ongoing habitat fragmentation and degradation of the natural environment. Our results emphasize the importance of molecular markers in species inventories of highly diverse organism groups and geographical areas.

The dispersal ecology of tropical non-vascular epiphytes has rarely been experimentally investigated. We studied epiphyte colonisation on 1 × 1 m polyethene nets placed for four years at seven sites at different elevations in montane forests in the Taita Hills, Kenya. During the first year the nets were also used to measure fog deposition. We predicted that differences in growth conditions would affect colonisation and subsequent growth of non-vascular epiphytes and result in clear differences in epiphyte cover and biomass, and community composition among sites. After four years the nets were taken down for determination of epiphyte cover and biomass. The diversity of established liverworts and macrolichens was also examined. Many liverwort and macrolichen species established diverse communities on the nets placed in the moist upper-montane zone. This was in contrast with the situation in the drier lower-montane zone where only green algae and crustose lichens were able to colonise most nets. Light intensity was an important determinant of epiphyte community composition, with liverworts dominating on nets under closed forest canopies and lichens dominating at more open sites. Atmospheric moisture was also important, with lichens benefiting from abundant fog deposition at open and windy sites. The dry weight of epiphytes (per unit area) on lichen-dominated nets was greater than on liverwort-dominated nets, while the highest cover was generally observed on liverwort-dominated nets. Our results demonstrate that polyethylene nets can be effectively used to study colonisation of non-vascular epiphytes as well as the abiotic and biotic factors controlling epiphyte colonisation and community composition in tropical forests. The liverworts Acanthocoleus chrysophyllus and Diplasiolejeunea kraussiana were new additions to the Kenyan bryophyte flora.

During lichenological explorations of tropical montane forests in Kenya, a remarkable new lichenicolous fungus was repeatedly found growing on thalli of the epiphytic tripartite cyanolichen Crocodia cf. clathrata. Molecular phylogenetic analyses placed the fungus within Gomphillaceae (Ostropales, Lecanoromycetes), a family mainly of lichen-symbiotic species in the tropics. The anatomical features (unitunicate, non-amyloid asci and simple, septate paraphyses) as well as the hemiangiocarpic ascoma development confirm its taxonomic affinity. DNA sequence data showed the closest relationship was with Gyalidea fritzei, followed by Corticifraga peltigerae. A monotypic genus, Taitaia, is introduced to incorporate a single species, T. aurea. The new fungus is characterized by aggregated ascomata with yellow margins and salmon red discs developing from a single base.

We studied the genotype diversity of cyanobacterial symbionts in the predominately terricolous cyanolichen genus Peltigera (Peltigerales, Lecanoromycetes) in Estonia. Our sampling comprised 252 lichen specimens collected in grasslands and forests from different parts of the country, which represented all common Peltigera taxa in the region. The cyanobacteria were grouped according to their tRNA(Leu) (UAA) intron sequences, and mycobiont identities were confirmed using fungal ITS sequences. The studied Peltigera species associated with 34 different "Peltigera-type" Nostoc trnL genotypes. Some Peltigera species associated with one or a few trnL genotypes while others associated with a much wider range of genotypes. Mycobiont identity was the primary factor that determined the presence of the specific Nostoc genotype within the studied Peltigera thalli. However, the species-specific patterns of cyanobiont selectivity did not always reflect phylogenetic relationships among the studied fungal species but correlated instead with habitat preferences. Several taxa from different sections of the genus Peltigera were associated with the same Nostoc genotype or with genotypes in the same habitat, indicating the presence of functional guild structure in the photobiont community. Some Nostoc trnL genotypes were only found in the Peltigera species of moist and mesic forest environments, while another set of Nostoc genotypes was typically found in the Peltigera species of xeric habitats. Some Nostoc trnL genotypes were only found in the Peltigera taxa that are common on alvars and may have specialized to living in this unusual and threatened habitat type. (C) 2018 Elsevier Ltd and British Mycological Society. All rights reserved.

Fossil tree resins preserve a wide range of animals, plants, fungi and microorganisms in microscopic fidelity. Fossil organisms preserved in an individual piece of amber lived at the same time in Earth history and mostly even in the same habitat, but they were not necessarily parts of the same interacting community. Here, we report on anin situpreserved corticolous community from a piece of Miocene Dominican amber which is composed of a lichen, a moss and three species of leafy liverworts. The lichen is assigned to the extant genusPhyllopsora(Ramalinaceae, Lecanoromycetes) and is described asP.magnaKaasalainen, Rikkinen & A. R. Schmidt sp. nov. The moss,Aptychellites fossilisSchäf.-Verw., Hedenäs, Ignatov & Heinrichs gen. & sp. nov., closely resembles the extant genusAptychellaof the family Pylaisiadelphaceae. The three leafy liverworts comprise the extinct Lejeuneaceae speciesCheilolejeunea antiqua(Grolle) Ye & Zhu, 2010 andLejeunea miocenicaHeinrichs, Schäf.-Verw., M. A. M. Renner & G. E. Lee sp. nov. and the extinct Radulaceae speciesRadula intectaM. A. M. Renner, Schäf.-Verw. & Heinrichs sp. nov. The presence of five associated extinct cryptogam species, four of which belong to extant genera, further substantiates the notion of a stasis in morphotype diversity, but a certain turnover of species, in the Caribbean since the early Miocene.

The widespread cyanolichen genus Peltigera comprises many insufficiently known poorly delimited and/or undescribed species. Phylogenetic analysis of 252 Peltigera specimens from a wide range of habitat types in Estonia revealed 31 putative taxa (OTUs). Multivariate analysis revealed habitat-specific segregation between the Peltigera species along a gradient from humid eutrophic forests to dry oligotrophic forests and grasslands and along a soil pH gradient from alkaline soils of alvar grasslands to acidic soils of conifer forests. The diversity of Peltigera was the highest on roadsides and dunes and the lowest in alvar habitats which, however, supported the unique assemblage of undescribed Peltigera taxa. Deciduous broad-leaved forests, too, included several undescribed or rare and red-listed species. The results demonstrate that in Estonia many Peltigera species have narrow habitat requirements and are at present threatened by habitat loss and degradation.

Epiphytes comprise a significant component of biodiversity and biomass in tropical forests. They are ecologically important in intercepting and retaining moisture, providing habitat and food for invertebrates, and contributing fixed nitrogen into the ecosystem. Lichens are mutualistic symbioses between lichen-forming fungi (mycobionts) and algae and/or cyanobacteria (photobionts). Most lichen mycobionts are specific in their photobiont choice and the local availability of compatible photobionts may limit their ability to disperse into new habitats. The aims of this study are to 1) provide the first account of lichen symbiont diversity in tropical mountains, with focus on changes along topographic gradients, and 2) elucidate the effects of human induced environmental change to lichen symbiotic organisms, including the effects of expansion of agricultural and other disturbed ecosystems, and changing climate. The results will be a significant contribution to understanding tropical biodiversity since so far very few studies deploying modern molecular biological methods have included lichens from East Africa. Lichens, bryophytes, and free-living cyanobacteria and green algae, along the natural environmental gradient of the southern slope of Kilimanjaro including all main ecosystem types. The sampling is focused on study plots established by the KiLi project . The collected specimens will be studied microscopically, with chemical analyses, and molecular biology methods. So far we have sampled several plots within the natural savanna, maize fields, grassland, and Chagga homegardens (3–5 sampled plots each ecosystem type). The specimens have been studied microscopically. The preliminary results show, that clear differences exist in lichen biota between different plot types: lichen abundance seems to depend especially on presence/absence of woody plants, lichen species on the climate, and lichen diversity on substrate variability. In all studied plots lichens mainly occur epiphytically on shrubs and trees. Non

Lichens are highly specialized symbioses between heterotrophic fungi and photoautotrophic green algae or cyanobacteria. The mycobionts of many lichens produce morphologically complex thalli to house their photobionts. Lichens play important roles in ecosystems and have been used as indicators of environmental change. Here we report the finding of 152 new fossil lichens from European Palaeogene amber, and hence increase the total number of known fossil lichens from 15 to 167. Most of the fossils represent extant lineages of the Lecanoromycetes, an almost exclusively lichen-symbiotic class of Ascomycota. The fossil lichens show a wide diversity of morphological adaptations that attached epiphytic thalli to their substrates, helped to combine external water storage with effective gas exchange and facilitated the simultaneous reproduction and dispersal of both partners in symbiosis. The fossil thallus morphologies suggest that the climate of European Palaeogene amber forests was relatively humid and most likely temperate.

Lichens are symbiotic associations between fungi and photosynthetic algae or cyanobacteria. Microcystins are potent toxins that are responsible for the poisoning of both humans and animals. These toxins are mainly associated with aquatic cyanobacterial blooms, but here we show that the cyanobacterial symbionts of terrestrial lichens from all over the world commonly produce microcystins. We screened 803 lichen specimens from five different continents for cyanobacterial toxins by amplifying a part of the gene cluster encoding the enzyme complex responsible for microcystin production and detecting toxins directly from lichen thalli. We found either the biosynthetic genes for making microcystins or the toxin itself in 12% of all analyzed lichen specimens. A plethora of different microcystins was found with over 50 chemical variants, and many of the variants detected have only rarely been reported from free-living cyanobacteria. In addition, high amounts of nodularin, up to 60 μg g −1 , were detected from some lichen thalli. This microcystin analog and potent hepatotoxin has previously been known only from the aquatic bloom-forming genus Nodularia . Our results demonstrate that the production of cyanobacterial hepatotoxins in lichen symbiosis is a global phenomenon and occurs in many different lichen lineages. The very high genetic diversity of the mcyE gene and the chemical diversity of microcystins suggest that lichen symbioses may have been an important environment for diversification of these cyanobacteria.

SummaryMicrocystins are a family of cyclic peptide toxins produced by cyanobacteria. They are responsible for the toxicosis and death of wild and domestic animals throughout the world. They display extensive variation in amino acid composition and functional group chemistry. O-acetylated microcystins are frequently produced by free-living and symbiotic strains of the genus Nostoc. Here, we show that the production of acetylated microcystins is catalyzed by an acetyl-coenzyme A-dependent O-acetyltransferase (McyL) encoded in the 57 kb microcystin synthetase gene cluster of Nostoc sp. 152. Phylogenetic analysis demonstrates that McyL belongs to a family of enzymes that inactivate antibiotics through O-acetylation. The McyL enzyme has a relaxed substrate specificity, allowing the preparation of semisynthetic microcystins. This study sheds light on the evolutionary origins and genetic diversity of an important class of enzymes involved in antibiotic resistance.

Lichens are symbiotic associations between a fungus (mycobiont) and a photosynthetic partner (photobiont) which may be a green alga or cyanobacterium (cyanobiont). In lichen symbiosis the mycobiont lives on sugars photosynthesized by the photobiont and, in cyanobacterial symbiosis, also nitrogen compounds are provided to the fungal host. Several cyanobacterial genera are known to associate with lichen forming fungi but by far the most common cyanobacterial genus in lichen symbioses is Nostoc. Lichen-symbiotic Nostoc is a diverse group including at least two distinct phylogenetic lineages which tend to associate with different groups of lichen mycobionts. Microcystins and nodularins are small, cyclic, hepatotoxic peptides responsible for poisonings of humans and animals. They are produced by aquatic, bloom forming cyanobacteria of several different genera and found in fresh and brackish waters around the world. The previously known microcystin producers of the genus Nostoc include the lichen associated cyanobacterium Nostoc sp. IO-102-I isolated from Finland, and some aquatic strains from Brazil, Finland, and India. While all producers of nodularin were previously thought to belong to the genus Nodularia, it has recently been shown that also some Nostoc strains isolated from cycad roots can produce nodularin. The aim of this study was to find out which cyanobacterial toxins are produced in lichen symbiosis and how widespread this production is, both from the geographical and lichen-symbiotic perspective. In addition I wanted to broaden the knowledge on lichen-symbiotic cyanobacteria and symbiont selectivity in lichen symbiosis. The study was based on the analysis of over 800 cyanolichen specimens collected from different parts of the world, mainly analysed with molecular biological methods and liquid chromatography-mass spectrometry. The results show that hepatotoxic microcystins are produced in situ in lichen symbioses by symbiotic cyanobacteria, and that these compounds are produced quite commonly in many different lichen genera all around the world. Also nodularin is produced in some lichens. The cyanobacterial toxins may act as grazing deterrents and provide some protection to the thallus. However the actual consequences to grazers and the faith of the toxins in the food chain remain unknown. The chemical and genetic diversity of microcystin production in lichens was remarkable. The evolution of this diversity may be related to genetic bottlenecks that commonly occur during the lifecycle of symbiotically dispersing cyanobacteria and the concurrent close association with the fungal hosts. The presently known distribution of toxin-producing cyanobacteria in lichens was found to concentrate into certain taxonomic groups within the Lobariaceae, Nephromataceae, and Peltigeraceae (Peltigerales, Ascomycota). The diversity of microcystin structures correlated with the genetic identity of Nostoc symbionts in different lichens, but also geographical patterns seemed to exist. Symbiont selection in the lichen genus Nephroma was found to be more specific locally than globally, and the identity of the cyanobiont to differ between bi- and tripartite members of the genus. Jäkälä on usean eri eliön muodostama symbioosi, jonka pääosakkaina ovat sieni (mykobiontti) ja yhteyttävä fotobiontti, joka voi olla joko viherlevä, syanobakteeri (syanobiontti) tai joissakin tapauksissa molemmat. Jäkäläsymbioosissa sieniosakas saa energiansa fotobiontin yhteyttämistuotteista, minkä lisäksi syanobiontti tarjoaa mykobiontille myös typpiyhdisteitä. Jäkäläsymbioosissa esiintyy useita eri syanobakteerisukuja, mutta selvästi yleisin suku on Nostoc. Jäkäläsymbioottiset Nostoc-syanobakteerit ovat hyvin monimuotoinen ryhmä, joka sisältää ainakin kaksi toisistaan eroavaa kehityslinjaa. Sieniosakkaiden on useimmiten todettu valikoivan symbioosikumppaninsa tietystä rajatusta joukosta, joka vaihtelee eri jäkäläsieniryhmien välillä. Mikrokystiinit ja nodulariinit ovat pieniä, rengasrakenteisia, maksamyrkyllisiä peptidejä, joiden tiedetään aiheuttaneen useita ihmisten ja eläinten myrkytystapauksia. Mikrokystiinien tutuimpia tuottajia ovat usean eri suvun makeassa ja murtovedessä elävät ja kukintoja muodostavat syanobakteerit. Nostoc-sukuun kuuluvia tunnettuja mikrokystiinin tuottajia ovat suomalaisesta jäkälästä eristetty kanta Nostoc sp. IO-102-I, sekä vesiympäristöistä eristetyt brasilialainen, intialainen ja suomalainen kanta. Perinteisesti vain Nodularia-syanobakteerisuvun edustajien on ajateltu tuottavan nodulariinia, mutta hyvin äskettäin myös käpypalmun (Cycas) juuresta eristetystä Nostoc-kannasta löydettiin tätä myrkkyä. Tässä tutkimuksessa halusin selvittää tuotetaanko syanobakteerimyrkkyjä myös jäkäläsymbioosissa, sekä kuinka yleistä niiden tuotanto maantieteellisestä ja jäkäläsystemaattisesta näkökulmasta on. Tämän lisäksi halusin laajentaa tietämystä sekä jäkäläsyanobionteista yleensä, että jäkäläsymbioosin osakkaiden valinnan tarkkuudesta. Tutkimus perustuu yli 800 eri puolilta maailmaa kerättyyn syanojäkälänäytteeseen, joita on pääasiassa analysoitu molekyylibiologisin menetelmin sekä nestekromatografi-massaspektrometrin avulla. Tuloksemme osoittavat että symbioottinen syanobakteeri tuottaa maksamyrkyllisiä mikrokystiinejä myös jäkäläsymbioosissa, ja että näitä yhdisteitä esiintyy melko yleisesti eri puolilla maailmaa ja useissa eri jäkäläryhmissä. Lisäksi muutamista jäkälänäytteistä löydettiin nodulariinia. Havaitsemamme mikrokystiineihin liittyvä geneettinen ja kemiallinen monimuotoisuus oli huomattavaa. Syy monimuotoisuuden kehittymiseen saattaa liittyä symbioottisesti leviävän syanobakteerin elinkierrossa säännöllisesti esiintyvään geneettiseen pullonkaulailmiöön sekä samanaikaiseen läheiseen vuorovaikutussuhteeseen sieni-isännän kanssa. Myrkkyjä tuottavat syanobiontit vaikuttaisivat olevan yleisimpiä tietyissä heimojen Lobariaceae, Nephromataceae ja Peltigeraceae (Peltigerales, Ascomycota) ryhmissä. Mikrokystiinirakenteiden vaihtelu noudattaa pääasiassa Nostoc-symbionttien kahta kehityslinjaa, mutta myös maantieteellisiä eroja esiintyy. On mahdollista että syanobakteerimyrkyt toimivat karkotteina ja tarjoavat suojaa jäkälänsyöjiä vastaan, mutta näiden myrkkyjen todelliset vaikutukset jäkäliä syöviin eläimiin ja niiden kohtalo ravintoketjussa kaipaavat vielä lisätutkimuksia. Jäkäläsuvussa Nephroma syanobionttien havaittiin eroavan kaksi- ja kolmebionttisten jäkälälajien välillä, ja lisäksi symbiontin valinta oli löyhempää maailmanlaajuisessa mittakaavassa kuin paikallisesti.

In symbiotic systems, patterns of symbiont diversity and selectivity are crucial for the understanding of fundamental ecological processes such as dispersal and establishment. The lichen genus Nephroma (Peltigerales, Ascomycota) has a nearly cosmopolitan distribution and is thus an attractive model for the study of symbiotic interactions over a wide range of spatial scales. In this study, we analyze the genetic diversity of Nephroma mycobionts and their associated Nostoc photobionts within a global framework. The study is based on Internal Transcribed Spacer (ITS) sequences of fungal symbionts and tRNA(L) (eu) (UAA) intron sequences of cyanobacterial symbionts. The full data set includes 271 Nephroma and 358 Nostoc sequences, with over 150 sequence pairs known to originate from the same lichen thalli. Our results show that all bipartite Nephroma species associate with one group of Nostoc different from Nostoc typically found in tripartite Nephroma species. This conserved association appears to have been inherited from the common ancestor of all extant species. While specific associations between some symbiont genotypes can be observed over vast distances, both symbionts tend to show genetic differentiation over wide geographic scales. Most bipartite Nephroma species share their Nostoc symbionts with one or more other fungal taxa, and no fungal species associates solely with a single Nostoc genotype, supporting the concept of functional lichen guilds. Symbiont selectivity patterns within these lichens are best described as a geographic mosaic, with higher selectivity locally than globally. This may reflect specific habitat preferences of particular symbiont combinations, but also the influence of founder effects.

In this study we reconstruct the structural evolution of the hyper-variable P6b region of the group I trnLeu intron in a monophyletic group of lichen-symbiotic Nostoc strains and establish it as a useful marker in the phylogenetic analysis of these organisms. The studied cyanobacteria occur as photosynthetic and/or nitrogen-fixing symbionts in lichen species of the diverse Nephroma guild. Phylogenetic analyses and secondary structure reconstructions are used to improve the understanding of the replication mechanisms in the P6b stem–loop and to explain the observed distribution patterns of indels. The variants of the P6b region in the Nostoc clade studied consist of different combinations of five sequence modules. The distribution of indels together with the ancestral character reconstruction performed enables the interpretation of the evolution of each sequence module. Our results indicate that the indel events are usually associated with single nucleotide changes in the P6b region and have occurred several times independently. In spite of their homoplasy, they provide phylogenetic information for closely related taxa. Thus we recognize that features of the P6b region can be used as molecular markers for species identification and phylogenetic studies involving symbiotic Nostoc cyanobacteria.

We show that the cyanobacterial symbionts of a tripartite cyanolichen can produce hepatotoxic microcystins in situ. Microcystins were detected with high-performance liquid chromatography mass spectrometry both from cephalodia of the tripartite cyanolichen Peltigera leucophlebia and from a symbiotic Nostoc strain isolated from the same lichen specimen. Genetic identities of symbiotic Nostoc strains were studied by amplifying and sequencing the 16S rRNA gene. Also, the presence of the microcystin synthetase gene mcyE was confirmed by sequencing. Three highly toxic microcystins were detected from the lichen specimen. Several different Nostoc 16S rRNA haplotypes were present in the lichen sample but only one was found in the toxin-producing cultures. In culture, the toxin-producing Nostoc strain produced a total of 19 different microcystin variants. In phylogenetic analysis, this cyanobacterium and related strains from the lichen thallus grouped together with a previously known microcystin-producing Nostoc strain and other strains previously isolated from the symbiotic thalloid bryophyte Blasia pusilla. Our finding is the first direct evidence of in situ production of microcystins in lichens or plant–cyanobacterial symbioses. Microcystins may explain why cyanolichens and symbiotic bryophytes are not among the preferred food sources of most animal grazers.

We studied lichen photobiont diversity patterns of three epiphytic Nephroma species in a 900-ha boreal forest landscape using cyanobacterial tRNALeu (UAA) intron sequences. Our aim was to investigate if there was a link between lichen species identity, reproductive strategy, and photobiont selectivity. We show high photobiont specificity and selectivity within the forest landscape: only five closely related tRNALeu (UAA) intron genotypes were found from 232 Nephroma thalli. Two Nostoc genotypes were shared by N. bellum and N. resupinatum, while N. parile associated with two different genotypes. One genotype was only found from some specimens of N. resupinatum. On a single tree trunk all thalli of an individual lichen species usually housed the same photobiont strain, and the lichen species that mainly dispersed with fungal diaspores (N. bellum and N. resupinatum) usually shared identical photobionts. Both patterns were attributed to a founder effect presumably caused by relatively low colonizatio...

Baltic amber forms the largest amber deposit on earth and it is particularly well-known for the plethora of arthropod inclusions. The floristic composition, habitat types and climate of its Eocene source area, however, are still controversial. The differing suggestions range from early Eocene tropical to late Eocene temperate environments, and from lowland to montane forests. We screened a large number of inclusions from historic collections and from recently discovered amber pieces and found many inclusions of seed plants, lichens and microfungi that provide important insights into habitat structure and climate.