Silke Werth

Silke Werth
Ludwig-Maximilians-University of Munich | LMU · Department of Biology I

Ph. D.

About

130
Publications
60,614
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2,316
Citations
Citations since 2017
25 Research Items
1138 Citations
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2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
Introduction
My research mainly deals with population genetics and genomics, using lichen-forming fungi of the Peltigerales as a model system. Current projects investigate gene expression lichen-forming fungi and their photobionts in response to environmental and biotic stressors. Other focal areas of my lab are lichen phylogeography and species diversity.
Additional affiliations
September 2014 - August 2020
University of Iceland
Position
  • Research Assistant
July 2012 - present
University of Iceland
February 2008 - June 2012
Swiss Federal Institute for Forest, Snow and Landscape Research WSL

Publications

Publications (130)
Article
Lichenicolous fungi are a species-rich biological group growing on lichen thalli. Here, we analyze the genetic structure of the lichenicolous basidiomycete Tremella lobariacearum and three host species (Lobaria pulmonaria, Lobaria macaronesica, and Lobaria immixta) in Macaronesia. We used ordination and analysis of molecular variance to investigate...
Article
Full-text available
Lichens, a classic example of an obligate symbiosis between fungi and photobionts (which could be algae or cyanobacteria), are abundant in many terrestrial ecosystems. The genetic structure of the photobiont population found in association with a lichen-forming fungal species could be affected by fungal reproductive mode and by the spatial extent o...
Article
Dispersal is a process critical for the dynamics and persistence of metapopulations, but it is difficult to quantify. It has been suggested that the old-forest lichen Lobaria pulmonaria is limited by insufficient dispersal ability. We analyzed 240 DNA extracts derived from snow samples by a L. pulmonaria-specific real-time PCR (polymerase chain rea...
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Lobaria pindarensis is an endemic species of the Himalayas and the Hengduan Mountains. Little information is available on the phylogeography genetics and colonization history of this species or how its distribution patterns changed in response to the orographic history of the Himalayas and Hengduan Mountains. Based on samples covering a major part...
Preprint
Photosymbiodemes are a special case of lichen symbiosis where one lichenized fungus engages in symbiosis with two different photosynthetic partners, a cyanobacterium and a green alga, to develop two distinctly looking photomorphs. We investigated differential gene expression in photosymbiodemes of the lichen Peltigera britannica at different temper...
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Antibiotics are primarily found in the environment due to human activity, which has been reported to influence the structure of biotic communities and the ecological functions of soil and water ecosystems. Nonetheless, their effects in other terrestrial ecosystems have not been well studied. As a result of oxidative stress in organisms exposed to h...
Article
Lichens serve as important bioindicators of air pollution in cities. Here, we studied the diversity of epiphytic lichens in an urban area in Munich, Bavaria, southern Germany, to determine which factors influence species composition and diversity. Lichen diversity was quantified in altogether 18 plots and within each, five deciduous trees were inve...
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Lichen symbioses are thought to be stabilized by the transfer of fixed carbon from a photosynthesizing symbiont to a fungus. In other fungal symbioses, carbohydrate subsidies correlate with reductions in plant cell wall-degrading enzymes, but whether this is true of lichen fungal symbionts (LFSs) is unknown. Here, we predict genes encoding carbohyd...
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Fungi involved in lichen symbioses produce a large array of secondary metabolites that are often diagnostic in the taxonomic delimitation of lichens. The most common lichen secondary metabolites—polyketides—are synthesized by polyketide synthases, particularly by Type I PKS (TI-PKS). Here, we present a comparative genomic analysis of the TI-PKS gen...
Preprint
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Fungi involved in lichen symbioses produce a large array of different secondary metabolites. The high diversity of those substances has been known for decades and are often considered characteristic for taxonomical delimitation in lichen-forming fungi. Polyketides, the most common secondary metabolites, are synthesized by the Type I Polyketide synt...
Article
In Graz (Austria) and Podgorica (Montenegro), epiphytic lichens and bryophytes were studied in 2017 based on a standardized approach. On 165 trees in Graz, 27 bryophyte and 38 lichen species were determined. In Podgorica, on 161 trees, 29 bryophyte and 52 lichen species were found. The mean epiphytic cover in Graz was significantly higher. Mean bry...
Article
Anthropogenic climate change has led to unprecedented shifts in temperature across many ecosystems. In a context of rapid environmental changes, acclimation is an important process as it may influence the capacity of organisms to survive under novel thermal conditions. Mechanisms of acclimation could involve upregulation of stress response genes in...
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To facilitate population-genetic studies, we developed simple sequence repeat (SSR) markers and a molecular species identification assay for Peltigera membranacea ( Ascomycota , Peltigerales ), a common ground-dwelling lichen of forest and tundra ecosystems. Additional markers were developed for its Nostoc photobiont. Twenty-one fungal markers for...
Preprint
Full-text available
Lichen symbioses are generally thought to be stabilized by the transfer of fixed carbon compounds from a photosynthesizing unicellular symbiont to a fungus. In other fungal symbioses, carbohydrate subsidies correlate with genomic reductions in the number of genes for plant cell wall-degrading enzymes (PCWDEs), but whether this is the case with lich...
Preprint
Anthropogenic climate change has led to unprecedented shifts in temperature across many ecosystems. In a context of rapid environmental changes, acclimation is an important process as it may influence the capacity of organisms to survive under novel thermal conditions. Mechanisms of acclimation could involve upregulation of stress response genes in...
Article
Full-text available
Macaronesia is characterized by a high degree of endemism and represents a noteworthy system to study the evolutionary history of populations and species. Here, we compare the population-genetic structure in three lichen-forming fungi, the widespread Lobaria pulmonaria and two Macaronesian endemics, L. immixta and L. macaronesica, based on microsat...
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The epiphytic lichen Lobaria pindarensis is a Himalayan endemic species with little information on distribution , genetic diversity and structural complexity. During an intensive survey in the Nepal Himalayas, we collected 1256 thallus fragments from 45 phorophyte species to study their distribution and population genetics along an elevational grad...
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The Hindu Kush Himalayan (HKH) region harbours some of the richest and most diverse ecosystems on the planet that are now facing substantial threats through changes in climate, land use and human population growth, with serious consequences for the biodiversity in this mountainous region. In this paper we evaluated the effects of climate change on...
Article
Front cover: The cover image of lace lichen (Ramalina menziesii) growing on California valley oak (Quercus lobata), in California, Hastings UC Reserve is based on the Research Paper Historical interactions are predicted to be disrupted under future climate change: The case of lace lichen and valley oak by Jian‐Li Zhao et al., DOI: 10.1111/jbi.13442...
Article
Aim The distributions and interactions of co‐occurring species may change if their ranges shift asymmetrically in response to rapid climate change. We aim to test whether two currently interacting taxa, valley oak (Quercus lobata) and lace lichen (Ramalina menziesii), have had a long‐lasting historical association and are likely to continue to asso...
Data
Fig. S1 Effective dispersal distance and probability of deposition to at least distance x for clonal propagules, gametes and ascospores in the epiphytic lichen‐forming ascomycete Lobaria pulmonaria. The figure represents analysis I, clones dropped. Fig. S2 Effective dispersal distance and probability of deposition to at least distance x for clonal...
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Lichen harvest and trade are closely associated with the livelihood of most of the rural people in Western Nepal. The present study investigates the commercial collection of lichens, quantifies the traded volume and relates it to a market scenario, and discusses conservation measures in relation to established legal practices in Nepal. Data on lich...
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Accurate estimates of gamete and offspring dispersal range are required for the understanding and prediction of spatial population dynamics and species persistence. Little is known about gamete dispersal in fungi, especially in lichen‐forming ascomycetes. Here, we estimate the dispersal functions of clonal propagules, gametes and ascospores of the...
Article
Riparian zones are some of the most valuable and at the same time endangered ecosystems in the world. Their progressive degradation caused by anthropogenic pressure calls for the adoption of effective, resilient restoration strategies. However, a full understanding of the complex mechanisms governing riparian ecosystems has not yet been achieved, a...
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During 2007-2014, voucher specimens of Lobariaceae were collected from different geographic locations of Taplejung, Solukhumbu, Rasuwa, Gorkha, Manang, Kaski, and Myagdi districts of Nepal. Morphological characters, chemical tests and thin-layer chromatography techniques (TLC) were applied for the identification. Combining with earlier publications...
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Background The aim of the study was to document the prevailing indigenous knowledge and various uses of lichens among the lichenophilic communities in the hills and mountainous settlements of Nepal. Methods Ethnic uses were recorded during twelve field trips, each of roughly 15 days in three consecutive years, through direct questionnaires administ...
Article
Werth, S., Reynisdóttir, S., Guðmundsson, H. & Andrésson, Ó. S. 2016. A fast and inexpensive high-throughput protocol for isolating high molecular weight genomic DNA from lichens. — Herzogia 29: 610–616. Isolating high molecular weight DNA as required for genomic library preparations and other applications is a challenging task. We optimized a glas...
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Phylogeography documents the spatial distribution of genetic lineages that result from demographic processes, such as population expansion, population contraction, and gene movement, shaped by climate fluctuations and the physical landscape. Because most phylogeographic studies have used neutral markers, the role of selection may have been underval...
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The capacity of species to cope with variation in the physical environment, e.g. in temperatures and temperature fluctuations, can limit their spatial distribution. Organisms have evolved cellular mechanisms to deal with damaging effects of increased temperature and other aggravation, primarily through complex molecular mechanisms including protein...
Article
Lichens comprise a symbiosis of two separate taxa that share geographical distribution but not necessarily the same evolutionary history. Comparison of phylogeographical structures of lichen symbionts provides valuable insight about the processes shaping the lichen's biogeographical pattern. In this study, we tested the extent to which the shared d...
Article
Major environmental gradients co-vary with elevation and have been a longstanding natural tool allowing ecologists to study global diversity patterns at smaller scales, and to make predictions about the consequences of climate change. These analyses have traditionally studied taxonomic diversity, but new functional diversity approaches may provide...
Chapter
The population genetics of lichen fungi and their photobionts have been studied for several decades. In this review, we first focus on basic questions in lichen population genetics and on recent and current experimental approaches. Then, we discuss the utility of single nucleotide polymorphism (SNP) markers and how various high-throughput sequencin...
Article
Garima Singh1,2,3,*,#, Francesco Dal Grande2,#, Silke Werth3,4 and Christoph Scheidegger31Department of Biological Sciences, Institute of Ecology, Evolution and Diversity, Goethe Universität, Max-von-Laue-Str. 13, D-60438 Frankfurt, Tel: +49 (0)69 7542 1851; Fax: +49 (0)69 7542 1800, Germany2Biodiversity and Climate Research Centre (BiK-F), Sencken...
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The effect of disturbance on symbiotic organisms such as lichens is particularly severe. In case of heterothallic lichen-forming fungi, disturbances may lead to unbalanced gene frequency and patchy distribution of mating types, thus inhibiting sexual reproduction and imposing clonality. The impact of disturbance on reproductive strategies and genet...
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Nepal is a small country but diverse in ethnic communities living in different parts of the country. These ethnic communities have been practicing the indigenous knowledge of plants for their livelihood. The objective of this study is to document the traditional knowledge of one of the most important medicinal plant species Taxus wallichiana Zucc....
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Predictions on potential sites of endangered species like Taxus wallichiana (Himalayan Yew) could help the conservation of this species. Based on collection information of 124 study sites and 18 herbarium records from the Southern slopes of Nepal Himalaya, we used species distribution modeling as implemented in Maxent. The information from collecti...
Article
Natural and man-made barriers have a significant impact on the population structure and genetic diversity of aquatic species. Little is known whether terrestrial, riparian species are affected in the same way by barriers.Here, we analysed the genetic structure of a threatened riparian shrub based on 20 microsatellite markers and 1176 individuals co...
Article
Population genetics of the tree-colonizing lichen Lobaria pulmonaria were studied in the largest primeval beech forest of Europe, covering 10 000 ha. During an intensive survey of the area, we collected 1522 thallus fragments originating from 483 trees, which were genotyped with 8 myco- and 14 photobiont-specific microsatellite markers. The mycobio...
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• Premise of the study: Many lichens exhibit extensive ranges spanning several ecoregions. It has been hypothesized that this wide ecological amplitude is facilitated by fungal association with locally adapted photobiont strains.• Methods: We studied the identity and geographic distribution of photobionts of the widely distributed North American li...
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One of the major distinctions of riparian habitats is their linearity. In linear habitats, gene flow is predicted to follow a one-dimensional stepping stone model, characterized by bidirectional gene flow between neighboring populations. Here, we studied the genetic structure of Myricaria germanica, a threatened riparian shrub which is capable of b...
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One of the major distinctions of riparian habitats is their linearity. In linear habitats, gene flow is predicted to follow a one-dimensional stepping stone model, characterized by bidirectional gene flow between neighboring populations. Here, we studied the genetic structure of Myricaria germanica, a threatened riparian shrub which is capable of b...
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• Premise of the study: Microsatellite loci were developed for the rare, Himalayan, endemic haploid lichen fungus, Lobaria pindarensis , to study its population subdivision and the species’ response to forest disturbance and fragmentation. • Methods and Results: We developed 18 polymorphic microsatellite markers using 454 pyrosequencing data and as...
Article
The complex topography and climate history of western North America offer a setting where lineage formation, accumulation, and migration have led to elevated inter- and intraspecific biodiversity in many taxa. Here, we study Ramalina menziesii, an epiphytic lichenized fungus with a range encompassing major ecosystems from Baja California to Alaska...
Article
As ploidy level and mating system can affect genetic diversity and differentiation, we conducted population genetic analyses of two closely related mosses, Scorpidium cossonii (Schimp.) Hedenäs, and S. revolvens (Sw. ex Anonymo) Rubers which differ in ploidy level and sexual system. We collected 315 specimens in total from five populations of S. co...
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The green algal photobionts of 12 Xanthoria, seven Xanthomendoza, two Teloschistes species and Josefpoeltia parva (all Teloschistaceae) were analyzed. Xanthoria parietina was sampled on four continents. More than 300 photobiont isolates were brought into sterile culture. The nuclear ribosomal internal transcribed spacer region (nrITS; 101 sequences...
Article
Propagule size has important consequences on the genetic structure of wind-dispersed species, as species with small propagules have higher capability of long-distance dispersal. Here, we studied reproductive modes and compared local and regional population structures in three Macaronesian lichenized fungi differing in propagule size. First, we quan...
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Nach erfolgreichem Abschluss der interdisziplinären Vorgängerprojekte «Rhone-Thur» und «Integrales Flussgebietsmanagement » wurde im Rahmen des durch das Bundesamt für Umwelt (BAFU) unterstützten Forschungsprogramms «Wasserbau und Ökologie» ein neues Projekt gestartet, welches sich auf die Geschiebe- und Habitatsdynamik in Fliessgewässern konzentri...
Data
We studied group I introns in sterile cultures of selected groups of lichen photobionts, focusing on Trebouxia species associated with Xanthoria s. lat. (including Xanthomendoza spp.; lichen-forming ascomycetes). Group I introns were found inserted after position 798 (Escherichia coli numbering) in the large subunit (LSU) rRNA in representatives of...
Article
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Photobiont diversity within populations of Xanthoria parietina was studied at the species level by means of ITS analyses and at the subspecific level with fingerprinting techniques (RAPD-PCR) applied to sterile cultured algal isolates. Populations from coastal, rural and urban sites from NW, SW and central France and from NE Switzerland were invest...
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• Premise of the study: Microsatellite primers were developed in the endangered tree species Taxus wallichiana from Nepal to investigate regional genetic differentiation, local genetic diversity, and gene flow for the conservation of this species under climate- and land-use change scenarios in mountain regions of Nepal. • Methods and Results: We de...
Article
Full-text available
Premise of the study: Microsatellite loci were developed for the threatened haploid lichen fungus Lobaria pulmonaria to increase the resolution to identify clonal individuals, and to study its population subdivision. Methods and Results: We developed 14 microsatellite markers from 454 DNA sequencing data of L. pulmonaria and tested for cross-ampli...
Article
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Microsatellites, also known as simple sequence repeats (SSRs), are among the most commonly used marker types in evolutionary and ecological studies. Next Generation Sequencing techniques such as 454 pyrosequencing allow the rapid development of microsatellite markers in nonmodel organisms. 454 pyrosequencing is a straightforward approach to develop...
Chapter
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Die verschiedenen Abschnitte eines Fliessgewässers sind Teile eines Ganzen und beein!ussen sich gegenseitig. Kenntnisse über die Vernetzung sind Voraussetzung dafür, lokale und regionale Prozesse in Fliessgewässern zu verstehen. Wie diese bei einer Revitalisierung am besten berücksichtigt werden können, zeigt das vorliegende Merkblatt.
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Vielfältige, naturnahe und dynamische Lebensräume sind eine wichtige Voraussetzung dafür, die Biodiversität in Fliessgewässern zu erhalten und zu fördern. Das vorliegende Merkblatt stellt die wichtigsten Faktoren für die Lebensraum- und Artenvielfalt vor und präsentiert Empfehlungen, mit welchen Massnahmen die Biodiversität erhöht werden kann.
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Naturnahe Fliessgewässer sind dynamische Systeme: Gewässersohle und Ufer werden regelmässig durch Hochwasser umgestaltet, wodurch neue Lebensräume entstehen. In den letzten Jahrzehnten wurde diese Dynamik vielerorts eingeschränkt, weil zahlreiche Fliessgewässer verbaut wurden. Ein wichtiges Ziel von Revitalisierungen ist, sie wiederherzustellen. Da...
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Availability of suitable trees is a primary determinant of range contractions and expansions of epiphytic species. However, switches between carrier tree species may blur co-phylogeographic patterns. We identified glacial refugia in southeastern Europe for the tree-colonizing lichen Lobaria pulmonaria, studied the importance of primeval forest rese...
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Lichens are a fascinating example of a symbiotic mutualism. It is still uncertain which processes guide fungal-photobiont interactions, and whether they are random or of a more complex nature. Here, I analyze the fungal-algal interactions in Ramalina menziesii and co-occurring taxa. Using DNA sequences of the algal Internal Transcribed Spacer regio...
Article
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Des habitats diversifiés, dynamiques et proches de l’état naturel sont indispensables à la conservation et à l’amélioration de la biodiversité dans les cours d’eau. Cette fiche présente les principaux facteurs de la diversité des habitats et des espèces, ainsi que des mesures permettant d’accroître la biodiversité
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Les cours d’eau proches de l’état naturel sont des systèmes dynamiques: le lit et les rives sont régulièrement modi!és par des crues, entraînant la création de nouveaux habitats. Durant les dernières décennies, cette dynamique a souvent été restreinte suite à l’endiguement de nombreuses rivières. Son rétablissement est un objectif important des rev...
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The extent of codispersal of symbionts is one of the key factors shaping genetic structures of symbiotic organisms. Concordant patterns of genetic structure are expected in vertically transmitted symbioses, whereas horizontal transmission generally uncouples genetic structures unless the partners are coadapted. Here, we compared the genetic structu...
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Biodiversität ist eine grundlegende Eigenschaft natürlicher Ökosysteme, die durch zunehmende menschliche Eingriffe in den letzten Jahrhunderten stark bedroht ist. Der komplexe Begriff Biodiversität umfasst die Vielfalt an Lebensräumen und Arten mit ihren ökologischen Funktionen und Interaktionen und ihrer genetischen Vielfalt. All diese Aspekte sin...
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Die funktionelle Vernetzung von Flussgebieten spielt eine wichtige Rolle für aquatische und terrestrische Lebensgemeinschaften. Sie erlaubt eine Besiedlung der Habitate, den genetischen Austausch zwischen Populationen und führt zu einer zeitlichen Verknüpfung der Lebensräume zu unterschiedlichen Jahreszeiten, Tageszeiten oder Lebensphasen. Die stru...
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The German tamarisk (Myricaria germanica) is a riparian shrub threatened in Europe, where populations are largely confined to the upstream areas of rivers. To study gene movement in this species within and among catchments, we isolated and characterized 22 nuclear and 5 chloroplast microsatellite loci and tested their polymorphism based on 40 indiv...
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Endozoochory plays a prominent role for the dispersal of seed plants. However, for most other plant taxa it is not known whether this mode of dispersal occurs at all. Among those other taxa, lichens as symbiotic associations of algae and fungi are peculiar as their successful dispersal requires movement of propagules that leaves the symbiosis funct...
Chapter
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Is the ‘Everything is everywhere’ hypothesis true for lichen fungi, taking into account the results of distribution-based and molecular studies, or does the ‘Vicariance’ hypothesis receive support? It is important to emphasise that our current knowledge of the biogeography of lichen fungi is very limited, which makes it hard to draw general conclus...