195 results on '"Christoph Scheidegger"'
Search Results
2. Gene flow in a pioneer plant metapopulation (Myricaria germanica) at the catchment scale in a fragmented alpine river system
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Sabine Fink, Andrea Hoppler-Wiedmer, Veronika Zengerer, Gregory Egger, Martin Schletterer, and Christoph Scheidegger
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Medicine ,Science - Abstract
Abstract River alterations for natural hazard mitigation and land reclamation result in habitat decline and fragmentation for riparian plant species. Extreme events such as floods are responsible for additional local species loss or population decline. Tributaries might provide refugia and subsequent source populations for the colonization of downstream sites in connected riverine networks with metapopulations of plant species. In this study, we analyzed the metapopulation structure of the endangered riparian shrub species Myricaria germanica along the river Isel, Austria, which is part of the Natura 2000 network, and its tributaries. The use of 22 microsatellite markers allowed us to assess the role of tributaries and single populations as well as gene flow up- and downstream. The analysis of 1307 individuals from 45 sites shows the influence of tributaries to the genetic diversity at Isel and no overall isolation by distance pattern. Ongoing bidirectional gene flow is revealed by the detection of first-generation migrants in populations of all tributaries as well as the river Isel, supporting upstream dispersal by wind (seeds) or animals (seeds and pollen). However, some populations display significant population declines and high inbreeding, and recent migration rates are non-significant or low. The genetic pattern at the mouth of river Schwarzach into Isel and shortly thereafter river Kalserbach supports the finding that geographically close populations remain connected and that tributaries can form important refugia for M. germanica in the dynamic riverine network. Conservation and mitigation measures should therefore focus on providing sufficient habitat along tributaries of various size allowing pioneer plants to cope with extreme events in the main channel, especially as they are expected to be more frequent under changing climate.
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- 2022
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3. Cyanobacteria: Extreme Environments and Toxic Metabolites
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Francesca Pittino, Juliana Oliveira, Mariana De Almeida Torres, Sabine Fink, Elisabeth M. L. Janssen, and Christoph Scheidegger
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Cyanobacteria ,Cyanotoxins ,Water quality ,Bioaccumulation ,Lichen ,Chemistry ,QD1-999 - Abstract
Cyanobacteria, also known as blue-green algae, are photosynthetic bacteria that can colonize different habitats, including extreme ones. They are of great interest to the scientific community, especially because of their ability to produce cyanotoxins: toxic secondary metabolites potentially harmful to organisms especially when released to surface waters.
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- 2022
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4. Deep divergence between island populations in lichenized fungi
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Silke Werth, Peter Meidl, and Christoph Scheidegger
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Medicine ,Science - Abstract
Abstract 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 microsatellites. We utilize population genetic approaches to explore population subdivision and evolutionary history of these taxa on the Canary Islands, Madeira, Azores, and the western Iberian Peninsula. A common feature in all species was the deep divergence between populations on the Azores, a pattern expected by the large geographic distance among islands. For both endemic species, there was a major split between archipelagos. In contrast, in the widespread L. pulmonaria, divergent individuals were distributed across multiple archipelagos, suggesting a complex evolutionary history involving repeated migration between islands and mainland.
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- 2021
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5. Gene flow in a highly dynamic habitat and a single founder event: Proof from a plant population on a relocated river site
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Romy Woellner, Christoph Scheidegger, and Sabine Fink
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Metapopulation ,Demography ,Colonization ,Floodplain ,Myricaria germanica ,Genetic diversity ,Ecology ,QH540-549.5 - Abstract
River relocations due to realization of infrastructure projects or flood protection provide a high potential for ecological restorations and the creation of near-natural habitats. Colonization success of new riparian habitats in the dynamic riverine zone is rarely predictable, as the survival of sessile plants is highly dependent on flood events. Relocated rivers offer a unique opportunity to study restoration success, and using genetic information allows tracing to source populations and assessing connectivity. This study focuses on the colonization of a new, 3.4 km long river stretch in the Inn catchment (Switzerland), with an artificial, stable shoreline and a dynamic riverine zone with gravel bars. We assess the colonization success of Myricaria germanica, a flagship species for floodplain pioneer vegetation, 14 years after river relocation. The population with over 600 individuals of which 147 were used for genetic analysis based on 22 microsatellite markers in comparison to 11 potential source populations up- and downstream of the new site. Our results on demography and genetic composition together with information on flood events allow tracing the origin of the subpopulation along the stable shoreline to a single founder event but several founder individuals further upstream. The subpopulation in the dynamic zone is younger and more likely strongly dependent on gene flow from the stable shoreline subpopulation, but allows for rejuvenation at the site. Genetic patterns along the catchment indicate ongoing gene flow, suggesting potential for colonization success for further restorations in the catchment. Our data reveals that near-natural flood dynamics with repeated larger flood events is a key factor for successful colonization of dynamic riparian habitats.
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- 2021
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6. Microsatellite based genetic diversity of the widespread epiphytic lichen Usnea subfloridana (Parmeliaceae, Ascomycota) in Estonia: comparison of populations from the mainland and an island
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Polina Degtjarenko, Inga Jüriado, Tiina Mandel, Tiiu Tõrra, Andres Saag, Christoph Scheidegger, and Tiina Randlane
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Botany ,QK1-989 - Abstract
Understanding the distribution of genetic patterns and structure is an essential target in population genetics and, thereby, important for conservation genetics. The main aim of our study was to investigate the population genetics of Usnea subfloridana, a widespread lichenised fungus, focusing on a comparison of genetic variation of its populations amongst three geographically remote and disconnected regions, in order to determine relationships amongst environmental data, variation in lichen secondary chemistry and microsatellite data in genotyped populations. In all, 928 Usnea thalli from 17 populations were genotyped using seven specific fungal microsatellite markers. Different measures of genetic diversity (allelic richness, private allelic richness, Nei’s unbiased genetic diversity and clonal diversity) were calculated and compared between lichen populations. Our results revealed a low genetic differentiation of U. subfloridana populations amongst three distant areas in Estonia and also a high level of gene flow. The results support suggestion of the long-range vegetative dispersal of subpendulous U. subfloridana via symbiotic propagules (soralia, isidia or fragments of thalli). Our study has also provided evidence that environmental variables, including mean annual temperature and geographical longitude, shape the genetic structure of U. subfloridana populations in Estonia. Additionally, a weak but statistically significant correlation between lichen chemotypes and microsatellite allele distribution was found in genotyped specimens.
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- 2019
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7. New species and records of Pyxine (Caliciaceae) in China
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Mei-Xia Yang, Xin-Yu Wang, Dong Liu, Yan-Yun Zhang, Li-Juan Li, An-Cheng Yin, Christoph Scheidegger, and Li-Song Wang
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Botany ,QK1-989 - Abstract
In this study, the diversity of Pyxine Fr. in China was assessed based on morphological and chemical traits and molecular data are inferred from ITS and mtSSU sequences. Nineteen species were recognised, including three that are new to science (i.e. P. flavicans M. X. Yang & Li S. Wang, P. hengduanensis M. X. Yang & Li S. Wang and P. yunnanensis M. X. Yang & Li S. Wang) and three records new to China were found (i.e. P. cognata Stirt., P. himalayensis Awas. and P. minuta Vain.). Pyxine yunnanensis is diagnosed by the small size of the apothecia, a white medulla of the stipe and the presence of lichexanthone. Pyxine flavicans is characterised by broad lobes, a pale yellow medulla of the stipe and the presence of atranorin. Pyxine hengduanensis can be distinguished by its pale yellow medulla, marginal labriform soralia and the absence of atranorin. Detailed descriptions of each new species are presented, along with a key to the known species of Pyxine in China.
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- 2019
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8. From natural forest to cultivated land: Lichen species diversity along land-use gradients in Kanchenjunga, Eastern Nepal
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Til Bikram Chongbang, Christine Keller, Michael Nobis, Christoph Scheidegger, and Chitra Bahadur Baniya
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Environmental sciences ,GE1-350 ,Geography (General) ,G1-922 - Published
- 2018
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9. Ethnolichenology—The Use of Lichens in the Himalayas and Southwestern Parts of China
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Mei-Xia Yang, Shiva Devkota, Li-Song Wang, and Christoph Scheidegger
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lichen ,ethnic use ,medicinal ,edible species ,Himalayas ,southwestern China ,Biology (General) ,QH301-705.5 - Abstract
Lichens are used in traditional medicine, food and various other ethnic uses by cultures across the Himalayas and southwestern parts of China. Evidence-based knowledge from historical and modern literatures and investigation of ethnic uses from 1990 proved that lichen species used as medicine in the Himalayas and southwestern parts of China totaled to 142 species; furthermore, 42 species were utilized as food. Moreover, some lichens are popularly used for lichen produce in ethnic and modern life. An understanding and clarification of the use of lichens in the Himalayas and southeastern parts of China can therefore be important for understanding uses of lichens elsewhere and a reference for additional research of lichen uses in the future.
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- 2021
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10. Rethinking Pumped Storage Hydropower in the European Alps: A Call for New Integrated Assessment Tools to Support the Energy Transition
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Astrid Björnsen Gurung, Axel Borsdorf, Leopold Füreder, Felix Kienast, Peter Matt, Christoph Scheidegger, Lukas Schmocker, Massimiliano Zappa, and Kathrin Volkart
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Austria ,energy transition ,Alps ,environmental impacts ,pumped storage hydropower ,sustainability assessment ,Switzerland ,Environmental sciences ,GE1-350 - Abstract
The European Alps are well positioned to contribute significantly to the energy transition. In addition to sites with above-average potential for wind and solar power, the “water towers” of Europe provide flexible, low-carbon power generation as well as energy storage. In the future, hydropower systems are expected to become more than mere electricity generators, serving a key role as flexible complements to intermittent power generators and as providers of large-scale seasonal and daily energy storage. Energy transition on national and European scales can be facilitated by expanding the capacity of pumped storage hydropower (PSHP) plants. Yet the extension of hydropower production, in particular PSHP, remains controversial, primarily due to environmental concerns. Focusing on 2 Alpine countries, Austria and Switzerland, this paper provides a system view of hydropower production and energy storage in the Alps. It discusses advantages and drawbacks of various assessment tools and identifies gaps and needs for the integrated assessment of PSHP plants. It concludes that instruments that evaluate the impacts and sustainability of PSHP projects need to be developed, elaborated, and applied in a participatory manner, in order to promote public dialogue, increase social acceptance, and, ideally, encourage energy consumers to become advocates of a sustainable energy future.
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- 2016
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11. Epiphytes in wooded pastures: Isolation matters for lichen but not for bryophyte species richness.
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Thomas Kiebacher, Christine Keller, Christoph Scheidegger, and Ariel Bergamini
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Medicine ,Science - Abstract
Sylvo-pastoral systems are species-rich man-made landscapes that are currently often severely threatened by abandonment or management intensification. At low tree densities, single trees in these systems represent habitat islands for epiphytic cryptogams. Here, we focused on sycamore maple (Acer pseudoplatanus) wooded pastures in the northern European Alps. We assessed per tree species richness of bryophytes and lichens on 90 sycamore maple trees distributed across six study sites. We analysed the effects of a range of explanatory variables (tree characteristics, environmental variables and isolation measures) on the richness of epiphytic bryophytes and lichens and various functional subgroups (based on diaspore size, habitat preference and red list status). Furthermore, we estimated the effect of these variables on the occurrence of two specific bryophyte species (Tayloria rudolphiana, Orthotrichum rogeri) and one lichen species (Lobaria pulmonaria) of major conservation concern. Bryophytes and lichens, as well as their subgroups, were differently and sometimes contrastingly affected by the variables considered: tree diameter at breast height had no significant effect on bryophytes but negatively affected many lichen groups; tree phenological age positively affected red-listed lichens but not red-listed bryophytes; increasing isolation from neighbouring trees negatively affected lichens but not bryophytes. However, the high-priority bryophyte species T. rudolphiana was also negatively affected by increased isolation at small spatial scales. Orthotrichum rogeri was more frequent on young trees and L. pulmonaria was more frequent on trees with thin stems and large crowns. The results indicate that local dispersal is important for lichens, whereas long distance dispersal seems to be more important for colonisation by bryophytes. Furthermore, our study highlights that different conservation measures need to be taken depending on the taxonomic and functional species group or the individual species that is addressed. In practice, for the conservation of a high overall richness in sylvo-pastoral systems, it is crucial to sustain not only old and large trees but rather a wide range of tree sizes and ages.
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- 2017
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12. Seasonal Changes in Bird Species and Feeding Guilds along Elevational Gradients of the Central Himalayas, Nepal.
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Hem Bahadur Katuwal, Khadga Basnet, Bhaiya Khanal, Shiva Devkota, Sanjeev Kumar Rai, Jyoti Prasad Gajurel, Christoph Scheidegger, and Michael P Nobis
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Medicine ,Science - Abstract
The Himalayas are a global hotspot for bird diversity with a large number of threatened species, but little is known about seasonal changes in bird communities along elevational gradients in this region. We studied the seasonality of bird diversity in six valleys of the Central Himalayas, Nepal. Using 318 plots with a 50 m radius, located from 2200 to 3800 m a.s.l., and repeated sampling during different seasons (mainly pre-monsoon, monsoon, and post-monsoon), we analyzed 3642 occurrences of 178 species. Birds classified in the literature as resident were more species-rich than migratory birds (140 vs. 38 species). In all six valleys and within the studied elevation range, species richness of all birds showed a peak at mid-elevation levels of 2600 or 3000 m a.s.l. Similar patterns were found for the most species-rich feeding guilds of insectivores (96 species) and omnivores (24 species), whereas the species richness of herbivores (37 species including frugivores) increased towards higher elevations. Among these feeding guilds, only species richness of insectivores showed pronounced seasonal changes with higher species numbers during post-monsoon season. Similarly, individual bird species showed distinct spatio-temporal distribution patterns, with transitions from species dominated by elevational differences to those characterized by strong seasonal changes. In an era of climate change, the results demonstrate that individual bird species as well as feeding guilds might greatly differ in their responses to climate warming and changes in the seasonality of the precipitation regime, two aspects of climate change which should not be analyzed independently.
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- 2016
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13. Congruent Genetic Structure in the Lichen-Forming Fungus Lobaria pulmonaria and Its Green-Algal Photobiont
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Silke Werth and Christoph Scheidegger
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Microbiology ,QR1-502 ,Botany ,QK1-989 - Abstract
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 structures of mutualists, the lichen-forming fungus Lobaria pulmonaria and its primary green-algal photobiont, Dictyochloropsis reticulata. We performed analysis of molecular variance and variogram analysis to compare genetic structures between symbiosis partners. We simulated the expected number of multilocus-genotype recurrences to reveal whether the distribution of multilocus genotypes of either species was concordant with panmixia. Simulations and tests of linkage disequilibrium provided compelling evidence for the codispersal of mutualists. To test whether genotype associations between symbionts were consistent with randomness, as expected under horizontal transmission, we simulated the recurrence of fungal-algal multilocus genotype associations expected by chance. Our data showed nonrandom associations of fungal and algal genotypes. Either vertical transmission or horizontal transmission coupled with coadaptation between symbiont genotypes may have created these nonrandom associations. This study is among the first to show codispersal and highly congruent genetic structures in the partners of a lichen mutualism.
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- 2012
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14. Genomic DNA Extraction and Genotyping of Dictyochloropsis Green Algae Strains
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Francesco Dal Grande, Carolina Cornejo, Christoph Scheidegger, and Andreas Beck
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Biology (General) ,QH301-705.5 - Abstract
Dictyochloropsis is an ecologically important genus of free-living and symbiotic green algae. Representatives of this genus are horizontally transmitted among several fungi of the family Lobariaceae, thus forming photobiont-mediated guilds. This protocol is suitable for extracting DNA from algal cultures and lichen samples and for genotyping seven unlinked Dictyochloropsis reticulata microsatellite markers in a single PCR multiplex.Figure 1. Schematic representation of the analysis pipeline
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- 2015
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15. Axenic Cultivation of Mycelium of the Lichenized Fungus, Lobaria pulmonaria (Peltigerales, Ascomycota)
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Carolina Cornejo, Christoph Scheidegger, and Rosmarie Honegger
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Biology (General) ,QH301-705.5 - Abstract
Lichens are symbiotic organisms consisting of a fungal partner (the mycobiont) and one or more algal or cyanobacterial partners (the photobiont); moreover lichen thalli comprise a plethora of epi- and endobiotic bacteria and non-lichenized fungi. Genetic markers are the most promising tools for the study of fungal diversity. However, applying genetic methods to intimately admixed symbiotic organisms typically requires the development of species-specific genetic markers, since DNA extraction from environmental specimens implicates the acquirement of total DNA of all symbionts and their cohabitants. While the cultivation of the alga is straight forward, the axenic cultivation of lichen-forming fungi is more difficult due to their very slow growth, as compared with the majority of non-lichenized taxa, and the presence of saprophytic, endophytic and parasitic fungi within the lichen thallus. Moreover, lichen-forming fungi (predominantly ascomycetes, few basidiomycetes) are oligotrophic organisms and thus adapted to nutrient poor conditions; in axenic culture on nutrient-rich media, as normally used for mass production of fast-growing saprophytic fungi, they often autointoxicate. Most lichen-forming fungi are not obligately biotrophic and thus can be cultured in the non-symbiotic state. Here, we present a protocol for the isolation of the lichen-forming ascomycete Lobaria pulmonaria into axenic culture and for mycelial mass culture as a source of pure fungal DNA. We describe the initiation of axenic cultures on agar plates from germinating ascospores and explain the optimization of the in vitro growth in liquid medium. By grinding the few dense, only centrifugally growing fungal colonies with a homogenizer we obtain lots of smaller, well growing colonies and thus higher amounts of mycelium for DNA or RNA isolation (Honegger and Bartnicki-Garcia, 1991).
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- 2015
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16. Effects of Management on Lichen Species Richness, Ecological Traits and Community Structure in the Rodnei Mountains National Park (Romania).
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Ioana Violeta Ardelean, Christine Keller, and Christoph Scheidegger
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Medicine ,Science - Abstract
Lichens are valuable bio-indicators for evaluating the consequences of human activities that are increasingly changing the earth's ecosystems. Since a major objective of national parks is the preservation of biodiversity, our aim is to analyse how natural resource management, the availability of lichen substrates and environmental parameters influence lichen diversity in Rodnei Mountains National Park situated in the Eastern Carpathians. Three main types of managed vegetation were investigated: the transhumance systems in alpine meadows, timber exploitation in mixed and pure spruce forests, and the corresponding conserved sites. The data were sampled following a replicated design. For the analysis, we considered not only all lichen species, but also species groups from different substrates such as soil, trees and deadwood. The lichen diversity was described according to species richness, red-list status and substrate-specialist species richness. The variation in species composition was related to the environmental variables. Habitat management was found to negatively influence species richness and alter the lichen community composition, particularly for threatened and substrate-specialist species. It reduced the mean level of threatened species richness by 59%, when all lichen species were considered, and by 81%, when only epiphytic lichens were considered. Management-induced disturbance significantly decreased lichen species richness in forest landscapes with long stand continuity. The diversity patterns of the lichens indicate a loss of species richness and change in species composition in areas where natural resources are still exploited inside the borders of the national park. It is thus imperative for protected areas, in particular old-growth forests and alpine meadows, to receive more protection than they have received in the past to ensure populations of the characteristic species remain viable in the future.
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- 2015
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17. Gene flow within and between catchments in the threatened riparian plant Myricaria germanica.
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Silke Werth and Christoph Scheidegger
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Medicine ,Science - Abstract
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 both wind and water dispersal. Our data led us to reject the 'one catchment-one gene pool' hypothesis as we found support for two gene pools, rather than four as expected in a study area including four catchments. This result also implies that in the history of the studied populations, dispersal across catchments has occurred. Two contemporary catchment-crossing migration events were detected, albeit between spatially proximate catchments. Allelic richness and inbreeding coefficients differed substantially between gene pools. There was significant isolation by distance, and our data confirmed the one-dimensional stepping-stone model of gene flow. Contemporary migration was bidirectional within the studied catchments, implying that dispersal vectors other than water are important for M. germanica.
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- 2014
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18. Genetic basis of self-incompatibility in the lichen-forming fungus Lobaria pulmonaria and skewed frequency distribution of mating-type idiomorphs: implications for conservation.
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Garima Singh, Francesco Dal Grande, Carolina Cornejo, Imke Schmitt, and Christoph Scheidegger
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Medicine ,Science - Abstract
Fungal populations that reproduce sexually are likely to be genetically more diverse and have a higher adaptive potential than asexually reproducing populations. Mating systems of fungal species can be self-incompatible, requiring the presence of isolates of different mating-type genes for sexual reproduction to occur, or self-compatible, requiring only one. Understanding the distribution of mating-type genes in populations can help to assess the potential of self-incompatible species to reproduce sexually. In the locally threatened epiphytic lichen-forming fungus Lobaria pulmonaria (L.) Hoffm., low frequency of sexual reproduction is likely to limit the potential of populations to adapt to changing environmental conditions. Our study provides direct evidence of self-incompatibility (heterothallism) in L. pulmonaria. It can thus be hypothesized that sexual reproduction in small populations might be limited by an unbalanced distribution of mating-type genes. We therefore assessed neutral genetic diversity (using microsatellites) and mating-type ratio in 27 lichen populations (933 individuals). We found significant differences in the frequency of the two mating types in 13 populations, indicating a lower likelihood of sexual reproduction in these populations. This suggests that conservation translocation activities aiming at maximizing genetic heterogeneity in threatened and declining populations should take into account not only presence of fruiting bodies in transplanted individuals, but also the identity and balanced representation of mating-type genes.
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- 2012
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19. Characterization of Microsatellite Loci in Lichen-Forming Fungi of Bryoria Section Implexae (Parmeliaceae)
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Olga Nadyeina, Carolina Cornejo, Carlos G. Boluda, Leena Myllys, Víctor J. Rico, Ana Crespo, and Christoph Scheidegger
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Ascomycetes ,Bryoria implexa ,lichen-forming fungi ,microsatellites ,Trebouxia spp ,Biology (General) ,QH301-705.5 ,Botany ,QK1-989 - Abstract
Premise of the study: The locally rare, haploid, lichen-forming fungi Bryoria capillaris, B. fuscescens, and B. implexa are associated with boreal forests and belong to Bryoria sect. Implexae. Recent phylogenetic studies consider them to be conspecific. Microsatellite loci were developed to study population structure in Bryoria sect. Implexae and its response to ecosystem disturbances. Methods and Results: We developed 18 polymorphic microsatellite markers using 454 pyrosequencing data assessed in 82 individuals. The number of alleles per locus ranged from two to 13 with an average of 4.6. Nei's unbiased gene diversity, averaged over loci, ranged from 0.38 to 0.52. The markers amplified with all three species, except for markers Bi05, Bi15, and Bi18. Conclusions: The new markers will allow the study of population subdivision, levels of gene introgression, and levels of clonal spread of Bryoria sect. Implexae. They will also facilitate an understanding of the effects of forest disturbance on genetic diversity of these lichen species.
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- 2014
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20. Characterization of Fungus-Specific Microsatellite Markers in the Lichen Fungus Usnea subfloridana (Parmeliaceae)
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Tiiu Tõrra, Carolina Cornejo, Saran Cheenacharoen, Francesco Dal Grande, Liis Marmor, and Christoph Scheidegger
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Ascomycetes ,lichen-forming fungi ,microsatellites ,population subdivision ,Usnea florida ,Usnea subfloridana ,Biology (General) ,QH301-705.5 ,Botany ,QK1-989 - Abstract
Premise of the study: Microsatellite loci were developed for the haploid lichenized fungal species Usnea subfloridana to study its population subdivision and the species' response to forest disturbance, fragmentation, and environmental pollution. Methods and Results: We developed 14 polymorphic microsatellite markers using 454 pyrosequencing data of U. subfloridana. The number of alleles per locus ranged from three to 15, and Nei's unbiased gene diversity averaged over nine markers without null alleles ranged from 0.64 to 0.67. Evaluation of the cross-species amplification in U. glabrescens and U. wasmuthii indicates that these markers are also informative in other Usnea species. Conclusions: These markers will allow us to investigate the effects of forest management and environmental pollution on genetic population structure of U. subfloridana and closely related species. Moreover, they will help facilitate phylogeographic studies of U. subfloridana across the species' distribution area in Europe.
- Published
- 2014
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21. Characterization of Microsatellite Loci in the Himalayan Lichen Fungus Lobaria pindarensis (Lobariaceae)
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Shiva Devkota, Carolina Cornejo, Silke Werth, Ram Prasad Chaudhary, and Christoph Scheidegger
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Ascomycetes ,Himalayas ,lichen-forming fungi ,Lobaria pindarensis ,microsatellites ,population subdivision ,Biology (General) ,QH301-705.5 ,Botany ,QK1-989 - Abstract
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 assessed them in 109 individuals. The number of alleles per locus ranged from three to 11 with an average of 6.9. Nei's unbiased gene diversity, averaged over loci, ranged from 0.514 to 0.685 in the three populations studied. The cross-amplification success with related species (L. chinensis, L. gyrophorica, L. isidiophora, L. orientalis, L. pulmonaria, L. spathulata, and Lobaria sp.) was generally high and decreased with decreasing relationship to L. pindarensis. Conclusions: The new markers will allow the study of genetic diversity and differentiation within L. pindarensis across its distribution. Moreover, they will enable us to study the effects of forest management on the genetic population structure of this tree-colonizing lichen and to carry out population genetic studies of related species in East Asia.
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- 2014
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22. Development and Characterization of Microsatellite Loci in the Endangered Species Taxus wallichiana (Taxaceae)
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Jyoti Prasad Gajurel, Carolina Cornejo, Silke Werth, Krishna Kumar Shrestha, and Christoph Scheidegger
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454 pyrosequencing ,conservation genetics ,Himalayan yew ,Himalayas ,simple sequence repeat marker ,Biology (General) ,QH301-705.5 ,Botany ,QK1-989 - Abstract
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 developed 10 highly polymorphic microsatellite markers from 454 DNA sequencing. Characterization of the new microsatellite loci was done in 99 individuals collected from three valleys with different climatic regimes. The number of alleles per locus varied from four to 12. Observed heterozygosity of populations, averaged across loci, ranged from 0.30 to 0.59. Conclusions: The new markers provided by this study will substantially increase the resolution for detailed studies in phylogeography, population genetics, and parentage analysis.
- Published
- 2013
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23. Characterization of Microsatellite Loci in the Lichen Fungus Lobaria pulmonaria (Lobariaceae)
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Silke Werth, Carolina Cornejo, and Christoph Scheidegger
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Ascomycetes ,Ascomycota ,lichen fungi ,Lobaria pulmonaria ,microsatellites ,population subdivision ,Biology (General) ,QH301-705.5 ,Botany ,QK1-989 - Abstract
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-amplification with L. immixta and L. macaronesica. The number of alleles per locus ranged from two to 23. Nei's unbiased gene diversity, averaged over loci, ranged from 0.434 to 0.517 in the three studied populations. Conclusions: The new markers will increase the genetic resolution in studies that aim at disentangling clones in L. pulmonaria and may be useful for closely related species within Lobaria sect. Lobaria.
- Published
- 2013
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24. Distribution of Lobaria pulmonaria (L.) Hoffm. in Mt Kilimanjaro and Mt Meru forests: altitudinal range and specificity to substratum tree species
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Nuru N. Kitara, Panteleo K. T. Munishi, and Christoph Scheidegger
- Subjects
Ecology, Evolution, Behavior and Systematics - Abstract
In this study, we sampled L. pulmonaria thalli from Mt Kilimanjaro and Mt Meru, Tanzania. Across all sampled tree species, a range of 1–35 thalli of L. pulmonaria were counted per trunk (up to 5 m above ground level), with sampling distributed across 13 (c. 1 ha) plots located in the sub-alpine to montane forest altitudinal gradients of Mt Kilimanjaro and Mt Meru. Descriptive analyses were performed to determine the association of L. pulmonaria with particular host trees among the study sites and regions, and linear mixed effects models (LMM) were used to explore relationships with tree-level variables. The analyses showed that most thalli of L. pulmonaria were unevenly distributed among the tree species in the montane and sub-alpine forests of Mt Kilimanjaro and Mt Meru. Host tree characteristics such as trunk circumference, height on trunk, bark texture and trunk shape appeared to have an effect on the local population size of L. pulmonaria and the frequency of occurrence. Also, the results indicated an effect of trunk circumference and tree bark on the development of L. pulmonaria thallus size among the study sites. Furthermore, host tree species, for example, Hypericum revolutum and Rapenea melanophloeos were important habitats for L. pulmonaria on both mountains, whereas Ilex mitis, Bersama abyssinica and Hagenia abyssinica were important only on one mountain. The wider literature on L. pulmonaria ecology is also reviewed and it is therefore recommended that for successful conservation of the threatened L. pulmonaria in tropical montane forests, strategies should consider the type of the forests, together with the host tree species and their size.
- Published
- 2022
25. Population genetics and biogeography of the lungwort lichen in North America support distinct Eastern and Western gene pools
- Author
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R. Troy McMullin, Jessica L. Allen, Yolanda F. Wiersma, and Christoph Scheidegger
- Subjects
Conservation genetics ,education.field_of_study ,Lichens ,biology ,Ecology ,Range (biology) ,Biogeography ,Species distribution ,Population ,Genetic Variation ,Population genetics ,Gene Pool ,Plant Science ,biology.organism_classification ,Genetics, Population ,Ascomycota ,North America ,Pulmonaria ,Genetics ,Gene pool ,education ,Phylogeny ,Ecology, Evolution, Behavior and Systematics - Abstract
PREMISE Populations of species with large spatial distributions are shaped by complex forces that differ throughout their ranges. To maintain the genetic diversity of species, genepool-based subsets of widespread species must be considered in conservation assessments. METHODS The population genetics of the lichenized fungus Lobaria pulmonaria and its algal partner, Symbiochloris reticulata, were investigated using microsatellite markers to determine population structure, genetic diversity, and degree of congruency in eastern and western North America. Data loggers measuring temperature and humidity were deployed at selected populations in eastern North America to test for climatic adaptation. To better understand the role Pleistocene glaciations played in shaping population patterns, a North American, range-wide species distribution model was constructed and hindcast to 22,000 years before present and at 500-year time slices from then to the present. KEY RESULTS The presence of two gene pools with minimal admixture was supported, one in the Pacific Northwest and one in eastern North America. Western populations were significantly more genetically diverse than eastern populations. There was no evidence for climatic adaptation among eastern populations, though there was evidence for range-wide adaptation to evapotranspiration rates. Hindcast distribution models suggest that observed genetic diversity may be due to a drastic Pleistocene range restriction in eastern North America, whereas a substantial coastal refugial area is inferred in the west. CONCLUSIONS Taken together the results show different, complex population histories of L. pulmonaria in eastern and western North America, and suggest that conservation planning for each gene pool should be considered separately. This article is protected by copyright. All rights reserved.
- Published
- 2021
26. Revision of Dimelaena Norman (Caliciaceae, Ascomycota) species containing usnic acid reveals a new species and a new combination from China
- Author
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MIN AI, QIUYI ZHONG, CHRISTOPH SCHEIDEGGER, LISONG WANG, and XINYU WANG
- Subjects
Ascomycota ,Fungi ,Caliciales ,Caliciaceae ,Plant Science ,Biodiversity ,Lecanoromycetes ,Ecology, Evolution, Behavior and Systematics ,Taxonomy - Abstract
Dimelaena tibetica is described as a species new to science, characterized by a grayish yellow surface, usually with a covering of white pruina, a crustose thallus, areolate at center, radiate-plicate at margin, adnate apothecia and lacking gyrophoric acid. It differs from other usnic acid-containing Dimelaena species by its plane marginal lobes and adnate apothecia. Based on the study of fresh specimens from the environment of the type locality, Dimelaena altissima is proposed as a new combination. A fresh specimen of Dimelaena oreina (type species of the genus Dimelaena) was collected in the Swiss Alps, in the vicinity of the area where the type material of the species presumably was collected, and a sequence was generated to confirm the phylogenetic position of this genus. All three species share common characters: usnic acid content and a yellowish green upper surface. Descriptions of these species were based on a combination of morphological and phylogenetic analyses. A key and phylogram are provided for these three Dimelaena species which produce usnic acid.
- Published
- 2022
27. A research agenda for nonvascular photoautotrophs under climate change
- Author
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Philipp Porada, Maaike Y. Bader, Monica B. Berdugo, Claudia Colesie, Christopher J. Ellis, Paolo Giordani, Ulrike Herzschuh, Yunyao Ma, Samuli Launiainen, Juri Nascimbene, Imke Petersen, José Raggio Quílez, Emilio Rodríguez‐Caballero, Kathrin Rousk, Leopoldo G. Sancho, Christoph Scheidegger, Steffen Seitz, John T. Van Stan, Maik Veste, Bettina Weber, David J. Weston, Porada, Philipp, Bader, Maaike Y, Berdugo, Monica B, Colesie, Claudia, Ellis, Christopher J, Giordani, Paolo, Herzschuh, Ulrike, Ma, Yunyao, Launiainen, Samuli, Nascimbene, Juri, Petersen, Imke, Raggio Quílez, José, Rodríguez-Caballero, Emilio, Rousk, Kathrin, Sancho, Leopoldo G, Scheidegger, Christoph, Seitz, Steffen, Van Stan, John T, Veste, Maik, Weber, Bettina, and Weston, David J
- Subjects
epiphytes ,nonvascular vegetation ,lichens and bryophyte ,model–data integration ,Physiology ,biocrusts ,Plant Science ,biocrust ,ecosystem service ,climate change ,lichens and bryophytes ,epiphyte ,functional traits ,functional trait ,ecosystem services ,model-data integration - Abstract
Nonvascular photoautotrophs (NVP), including bryophytes, lichens, terrestrial algae, and cyanobacteria, are increasingly recognized as being essential to ecosystem functioning in many regions of the world. Current research suggests that climate change may pose a substantial threat to NVP, but the extent to which this will affect the associated ecosystem functions and services is highly uncertain. Here, we propose a research agenda to address this urgent question, focusing on physiological and ecological processes that link NVP to ecosystem functions while also taking into account the substantial taxonomic diversity across multiple ecosystem types. Accordingly, we developed a new categorization scheme, based on microclimatic gradients, which simplifies the high physiological and morphological diversity of NVP and world-wide distribution with respect to several broad habitat types. We found that habitat-specific ecosystem functions of NVP will likely be substantially affected by climate change, and more quantitative process understanding is required on (1) potential for acclimation, (2) response to elevated CO2, (3) role of the microbiome, and (4) feedback to (micro)climate. We suggest an integrative approach of innovative, multimethod laboratory and field experiments and ecophysiological modelling, for which sustained scientific collaboration on NVP research will be essential.
- Published
- 2022
28. Changing climate requires shift from refugia to sanctuaries for floodplain forests
- Author
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Sabine Fink and Christoph Scheidegger
- Subjects
Ecological niche ,geography.geographical_feature_category ,Ecology ,Floodplain ,Geography, Planning and Development ,Species distribution ,Climate change ,Geography ,Habitat ,Biological dispersal ,Landscape ecology ,Nature and Landscape Conservation ,Riparian zone - Abstract
Context Riparian areas are considered to undergo major alterations under changing climate, making floodplain habitats targets for conservation and landscape planning. Protected areas might provide sanctuaries especially for sessile riparian plant species, but these niches are not always persistent over time. Objectives We investigate if plant species of floodplain forests are provided with suitable habitat within currently protected areas and if these refugia persist. A coupled-modelling approach is used to gain spatially explicit information on new areas for sanctuaries. Methods We use species distribution models to predict the niche of 12 Salicion albae and 7 Fraxinion floodplain forest species along rivers in Switzerland, under current, moderate and extreme climate change scenarios up to 80 years to the future (2100). The spread of plant species from current habitat to suitable future habitat is simulated using dispersal vectors and life history traits. Results Salicion albae species are more flexible under both climate change scenarios than Fraxinion species. The main limitation for the spread of species is their dispersal ability, as only a minority of the suitable cells is colonized during the simulation process. The predicted future presence within currently protected areas decreases under both climate change scenarios in the model. Conclusions Current protected floodplains do not provide persistent refugia for the plants studied, but might still be of importance to other organisms. Planning of sanctuaries for riparian plant species and communities need to focus on connectivity along rivers to maintain viable source populations in dynamic riverine landscapes under changing climate.
- Published
- 2021
29. Saproxylic species are linked to the amount and isolation of dead wood across spatial scales in a beech forest
- Author
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Thomas Kiebacher, Christian Ginzler, Thibault Lachat, Stefan Blaser, Elena Haeler, Karin Hindenlang, Ronald Schmidt, Christoph Scheidegger, Loïc Pellissier, Jonas Stillhard, Christine Keller, Alexander Szallies, Ariel Bergamini, Urs G. Kormann, University of Zurich, and Haeler, Elena
- Subjects
Geography, Planning and Development ,Beta diversity ,Biodiversity ,580 Plants (Botany) ,Biodiversity conservation ,2309 Nature and Landscape Conservation ,Scale dependence ,Connectivity ,Forest management ,Habitat amount hypothesis ,3305 Geography, Planning and Development ,10211 Zurich-Basel Plant Science Center ,Nature and Landscape Conservation ,Planning and Development ,Geography ,Ecology ,10121 Department of Systematic and Evolutionary Botany ,High forest ,Habitat ,Spatial ecology ,Alpha diversity ,Species richness ,Landscape ecology ,2303 Ecology - Abstract
Context Dead wood is a key habitat for saproxylic species, which are often used as indicators of habitat quality in forests. Understanding how the amount and spatial distribution of dead wood in the landscape affects saproxylic communities is therefore important for maintaining high forest biodiversity. Objectives We investigated effects of the amount and isolation of dead wood on the alpha and beta diversity of four saproxylic species groups, with a focus on how the spatial scale influences results. Methods We inventoried saproxylic beetles, wood-inhabiting fungi, and epixylic bryophytes and lichens on 62 plots in the Sihlwald forest reserve in Switzerland. We used GLMs to relate plot-level species richness to dead wood amount and isolation on spatial scales of 20–200 m radius. Further, we used GDMs to determine how dead wood amount and isolation affected beta diversity. Results A larger amount of dead wood increased beetle richness on all spatial scales, while isolation had no effect. For fungi, bryophytes and lichens this was only true on small spatial scales. On larger scales of our study, dead wood amount had no effect, while greater isolation decreased species richness. Further, we found no strong consistent patterns explaining beta diversity. Conclusions Our multi-taxon study shows that habitat amount and isolation can strongly differ in the spatial scale on which they influence local species richness. To generally support the species richness of different saproxylic groups, dead wood must primarily be available in large amounts but should also be evenly distributed because negative effects of isolation already showed at scales under 100 m., Landscape Ecology, 36 (1), ISSN:0921-2973, ISSN:1572-9761
- Published
- 2020
30. Short Communication: Co-occurring Lobaria pulmonaria and Ricasolia quercizans share green algal photobionts: Consequences for conservation
- Author
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Jessica L. Allen and Christoph Scheidegger
- Subjects
Plant Science ,Ecology, Evolution, Behavior and Systematics - Published
- 2022
31. Contrasting co‐occurrence patterns of photobiont and cystobasidiomycete yeast associated with common epiphytic lichen species
- Author
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Ülo Niinemets, Lauri Laanisto, Kristiina Mark, Christoph Scheidegger, C. Guillermo Bueno, and Christine Keller
- Subjects
0106 biological sciences ,0301 basic medicine ,Trebouxia ,Lichens ,Physiology ,Lineage (evolution) ,Saccharomyces cerevisiae ,Plant Science ,Fungus ,01 natural sciences ,03 medical and health sciences ,stomatognathic system ,Symbiosis ,Internal transcribed spacer ,Lichen ,Phylogeny ,biology ,Ecology ,biology.organism_classification ,Yeast ,stomatognathic diseases ,030104 developmental biology ,Epiphyte ,Switzerland ,010606 plant biology & botany - Abstract
The popular dual definition of lichen symbiosis is under question with recent findings of additional microbial partners living within the lichen body. Here we compare the distribution and co-occurrence patterns of lichen photobiont and recently described secondary fungus (Cyphobasidiales yeast) to evaluate their dependency on lichen host fungus (mycobiont). We sequenced the nuclear internal transcribed spacer (ITS) strands for mycobiont, photobiont, and yeast from six widespread northern hemisphere epiphytic lichen species collected from 25 sites in Switzerland and Estonia. Interaction network analyses and multivariate analyses were conducted on operational taxonomic units based on ITS sequence data. Our study demonstrates the frequent presence of cystobasidiomycete yeasts in studied lichens and shows that they are much less mycobiont-specific than the photobionts. Individuals of different lichen species growing on the same tree trunk consistently hosted the same or closely related mycobiont-specific Trebouxia lineage over geographic distances while the cystobasidiomycete yeasts were unevenly distributed over the study area - contrasting communities were found between Estonia and Switzerland. These results contradict previous findings of high mycobiont species specificity of Cyphobasidiales yeast at large geographic scales. Our results suggest that the yeast might not be as intimately associated with the symbiosis as is the photobiont.
- Published
- 2020
32. Distribution and assessment of the conservation status of Erioderma pedicellatum in Asia
- Author
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Irina S. Stepanchikova, Gulnara Tagirdzhanova, Dmitry E. Himelbrant, Marina Vyatkina, Aleksandra V. Dyomina, Christoph Scheidegger, and Veronika G. Dirksen
- Subjects
0106 biological sciences ,education.field_of_study ,geography.geographical_feature_category ,biology ,Ecology ,Erioderma pedicellatum ,Population ,Old-growth forest ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Habitat destruction ,Geography ,Habitat ,IUCN Red List ,Conservation status ,education ,Lichen ,Ecology, Evolution, Behavior and Systematics ,010606 plant biology & botany - Abstract
The first detailed survey is presented of a recently discovered population of Erioderma pedicellatum, a globally rare lichen, in the primeval spruce forests of the Kamchatka Peninsula, Russia. Three subpopulations are described, located in the Levaya Schapina River basin, in the Kimitina River basin, and on the slopes of the extinct volcano, Nikolka. In total, we observed 1894 thalli on 167 Yezo spruce trunks. In Kamchatka, E. pedicellatum occurs exclusively on bark-covered spruce twigs of mainly young and dwarf-stressed older trees. We discovered a high number of juvenile thalli, which suggests that this population is reproducing. However, its habitat is declining because spruce forests in the region are the target of industrial clear-cutting and there is a high incidence of forest fires. Over the next 60 years, which corresponds to three generations of E. pedicellatum, we infer that continued habitat loss will induce a 48% decline in these lichen populations. As a result of our analyses, the Asian population is classified as ‘Vulnerable’, based on IUCN Red List criteria.
- Published
- 2019
33. Genetic diversity and structure of the epiphytic foliose lichen Lobaria pindarensis in the Himalayas depends on elevation
- Author
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Shiva Devkota, Ram Prasad Chaudhary, Christoph Scheidegger, and Silke Werth
- Subjects
0106 biological sciences ,Genetic diversity ,Ecology ,biology ,Ecological Modeling ,Foliose lichen ,Population genetics ,Plant Science ,15. Life on land ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Lobaria ,Species richness ,Epiphyte ,Gene pool ,Lichen ,human activities ,Ecology, Evolution, Behavior and Systematics ,010606 plant biology & botany - Abstract
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 gradient. We quantified genetic diversity and population structure of each symbiont at 17 fungus specific and 9 alga specific microsatellite loci. The Bayesian clustering identified three and two distinct gene pools for mycobiont and photobiont. We found that genetic diversity, allelic richness and gene pool composition and distribution were significantly influenced by elevation. We discovered both clonally and sexually reproduced repeated genotypes of the symbionts.
- Published
- 2019
34. Gene flow in a pioneer plant metapopulation (Myricaria germanica) at the catchment scale in a fragmented alpine river system
- Author
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Sabine, Fink, Andrea, Hoppler-Wiedmer, Veronika, Zengerer, Gregory, Egger, Martin, Schletterer, and Christoph, Scheidegger
- Subjects
Gene Flow ,Rivers ,Tamaricaceae ,Endangered Species ,Animals ,Genetic Variation ,Ecosystem ,Microsatellite Repeats - Abstract
River alterations for natural hazard mitigation and land reclamation result in habitat decline and fragmentation for riparian plant species. Extreme events such as floods are responsible for additional local species loss or population decline. Tributaries might provide refugia and subsequent source populations for the colonization of downstream sites in connected riverine networks with metapopulations of plant species. In this study, we analyzed the metapopulation structure of the endangered riparian shrub species Myricaria germanica along the river Isel, Austria, which is part of the Natura 2000 network, and its tributaries. The use of 22 microsatellite markers allowed us to assess the role of tributaries and single populations as well as gene flow up- and downstream. The analysis of 1307 individuals from 45 sites shows the influence of tributaries to the genetic diversity at Isel and no overall isolation by distance pattern. Ongoing bidirectional gene flow is revealed by the detection of first-generation migrants in populations of all tributaries as well as the river Isel, supporting upstream dispersal by wind (seeds) or animals (seeds and pollen). However, some populations display significant population declines and high inbreeding, and recent migration rates are non-significant or low. The genetic pattern at the mouth of river Schwarzach into Isel and shortly thereafter river Kalserbach supports the finding that geographically close populations remain connected and that tributaries can form important refugia for M. germanica in the dynamic riverine network. Conservation and mitigation measures should therefore focus on providing sufficient habitat along tributaries of various size allowing pioneer plants to cope with extreme events in the main channel, especially as they are expected to be more frequent under changing climate.
- Published
- 2021
35. Gene flow in a highly dynamic habitat and a single founder event: Proof from a plant population on a relocated river site
- Author
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Christoph Scheidegger, Sabine Fink, and Romy Woellner
- Subjects
0106 biological sciences ,Colonization ,Floodplain ,Population ,Drainage basin ,010603 evolutionary biology ,01 natural sciences ,Genetic diversity ,education ,Ecology, Evolution, Behavior and Systematics ,QH540-549.5 ,Nature and Landscape Conservation ,Riparian zone ,Demography ,geography ,education.field_of_study ,geography.geographical_feature_category ,Flood myth ,Ecology ,010604 marine biology & hydrobiology ,Vegetation ,Myricaria germanica ,ddc ,Habitat ,Metapopulation - Abstract
River relocations due to realization of infrastructure projects or flood protection provide a high potential for ecological restorations and the creation of near-natural habitats. Colonization success of new riparian habitats in the dynamic riverine zone is rarely predictable, as the survival of sessile plants is highly dependent on flood events. Relocated rivers offer a unique opportunity to study restoration success, and using genetic information allows tracing to source populations and assessing connectivity. This study focuses on the colonization of a new, 3.4 km long river stretch in the Inn catchment (Switzerland), with an artificial, stable shoreline and a dynamic riverine zone with gravel bars. We assess the colonization success of Myricaria germanica, a flagship species for floodplain pioneer vegetation, 14 years after river relocation. The population with over 600 individuals of which 147 were used for genetic analysis based on 22 microsatellite markers in comparison to 11 potential source populations up- and downstream of the new site. Our results on demography and genetic composition together with information on flood events allow tracing the origin of the subpopulation along the stable shoreline to a single founder event but several founder individuals further upstream. The subpopulation in the dynamic zone is younger and more likely strongly dependent on gene flow from the stable shoreline subpopulation, but allows for rejuvenation at the site. Genetic patterns along the catchment indicate ongoing gene flow, suggesting potential for colonization success for further restorations in the catchment. Our data reveals that near-natural flood dynamics with repeated larger flood events is a key factor for successful colonization of dynamic riparian habitats.
- Published
- 2021
36. 2.4 High alpine lichens
- Author
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Christoph Scheidegger
- Subjects
Ecology ,Environmental science ,Lichen - Published
- 2021
37. Correction: Barcoding lichen-forming fungi using 454 pyrosequencing is challenged by artifactual and biological sequence variation
- Author
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Kristiina Mark, Carolina Cornejo, Christine Keller, Daniela Flück, and Christoph Scheidegger
- Subjects
Genetics ,General Medicine ,Molecular Biology ,Biotechnology - Published
- 2021
38. The effects of ozone and nutrient supply on stomatal response in birch (Betula pendula) leaves as determined by digital image-analysis and X-ray microanalysis
- Author
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Rainer Matyssek, Beat Frey, Christoph Scheidegger, and Madeleine S. Günthardt-Goerg
- Subjects
Betulaceae ,Ozone ,biology ,Physiology ,Chemistry ,Potassium ,Fumigation ,chemistry.chemical_element ,Plant Science ,Liquid nitrogen ,biology.organism_classification ,chemistry.chemical_compound ,Horticulture ,Human fertilization ,Nutrient ,Guard cell ,Botany - Abstract
SUMMARY Cuttings of Betula pendula Roth were grown in field fumigation chambers throughout one growing season in filtered air with < 3 nl l−1 O3 (control; C) or day/night = 90/40 nl 1−1 O3 (ozone fumigation: O3). Plants were watered with either low (0·005 %: LF) or high-concentrated (0·05%: HF) fertilizer solution. Discs between second-order veins in the central portion of the leaves were excised and immediately cryofixed in liquid nitrogen for low-temperature scanning electron-microscopy (LTSEM) at 1000 hours and 1400 hours. Stomatal width, area and density were measured by digital image-analysis. X-ray counts of potassium (K) and calcium (Ca) ions were determined by means of energy-dispersive X-ray microanalysis in guard and subsidiary cells. Accurate and fast measurements of stomatal apertures by image analysis were possible in birch leaves, because the darkness of the stomatal pore contrasts with the brightness of the guard cells and the cuticular ledges. Regression analysis showed a close relationship between the stomatal width and the pore area (r= 0·938, P < 0·01). At all harvest times, the stomatal pores were significantly narrowed in the high fertilization control treatment (O3/HF vs. O3/LF), and in the ozone treatment at 1400 hours (O3/HF vs. C/LF). In addition to this fertilization effect, ozone had also narrowed the stomatal pores (O3/HF vs. C/HF at 1400 hours, O3/LF vs. C/LF at all harvest times). In addition to these functional effects, morphological effects (individual leaf area, stomatal density) were determined. Single-leaf area was increased by high fertilization, with a tendency to decrease with O3 fumigation. The stomatal density in intercostal fields was increased by O3 but decreased by high fertilisation. Stomatal widening was accompanied by increased K count rates in the guard cells, in contrast to constant K values in the subsidiary cells, irrespective of the fumigation or fertilization regimes. Calcium counts in the guard cells were similar to those in the subsidiary cells, and were independent of the aperture width. In samples with established ozone injury, the K/Ca ratio in collapsed guard cells increased compared with turgid guard cells irrespective of the pore aperture. Collapsed subsidiary cells only differed from turgid subsidiary cells when the guard cells had also collapsed and thus closed the pore.
- Published
- 2021
39. Autochthone Gebirgswälder in der Schweiz anhand von baumbewohnenden Flechten erkennen
- Author
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Lyudmyla Dymytrova, Silvia Stofer, Christoph Scheidegger, and Urs-Beat Brändli
- Subjects
Geography ,Forestry - Abstract
Recognizing autochthonous mountain forests in Switzerland by means of epiphytic lichens Old undisturbed forest stands with a long forest history are of particular interest for nature and species conservation. Epiphytic lichens are often used as indicators for such autochthonous stands. In this study, we tested to what extent 14 taxa of epiphytic lichens, which are easy to identify by forest practitioners and have a low dispersal potential, have specific requirements for micro habitats and are often dependent on old trees, would be suitable indicator species for autochthonous forest stands in the Swiss mountain forests. As autochthonous, we considered forest stands with a near-natural conifer composition, a minimum age of 90 years, a continuous forest cover over 120 years and no evidence of historical intervention such as clear cutting or afforestation. For the study, the regular field teams of the Swiss National Forest Inventory (NFI) included the potential indicator species in the third survey (2004–2006) on all plots in the 1.4 km network on about three trees each. The data for the 3510 plots in the mountain forest were then evaluated using the NFI data on forest structure, forest history and forest management. Overall, the number of indicator species was significantly higher in autochthonous forest stands than in non-autochthonous ones, although it varied considerably with altitude and biogeographical region. Our investigations showed that fruticose lichens of the genera Bryoria and Usnea, Evernia divaricata and Letharia vulpina, foliose lichens such as Cetrelia olivetorum and Lobaria pulmonaria, and crustose lichens such as Lecanactis abietina and Microcalicium disseminatum, Calicium sp. div. and Chaenotheca sp. div. as well as Chrysothrix candelaris are reliable indicators for autochthonous stands in Swiss mountain forests, especially if several indicator species occur together. The lichens tested are therefore suitable in practice for a simple identification of autochthonous forest stands, e.g. for delimiting forest reserves or old forest patches. These stands are of high importance for the promotion of biodiversity in a forest landscape that has been managed for centuries.
- Published
- 2019
40. Microsatellite based genetic diversity of the widespread epiphytic lichen Usnea subfloridana (Parmeliaceae, Ascomycota) in Estonia: comparison of populations from the mainland and an island
- Author
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Tiina Randlane, Inga Jüriado, Andres Saag, Tiiu Tõrra, Polina Degtjarenko, Christoph Scheidegger, and Tiina Mandel
- Subjects
0106 biological sciences ,0301 basic medicine ,Conservation genetics ,Estonia ,Usnea ,Lecanorales ,Chemotypes ,Usnea subfloridana ,Population genetics ,010603 evolutionary biology ,01 natural sciences ,microsatellites ,03 medical and health sciences ,Ascomycota ,environmental factors ,lcsh:Botany ,lichenised fungi ,Genetic variation ,Parmeliaceae ,Ecology, Evolution, Behavior and Systematics ,Genetic diversity ,biology ,Ecology ,Fungi ,genetic diversity ,biology.organism_classification ,lcsh:QK1-989 ,030104 developmental biology ,Genetic structure ,Biological dispersal ,Lecanoromycetes ,Population Genetics ,Research Article - Abstract
Understanding the distribution of genetic patterns and structure is an essential target in population genetics and, thereby, important for conservation genetics. The main aim of our study was to investigate the population genetics of Usnea subfloridana, a widespread lichenised fungus, focusing on a comparison of genetic variation of its populations amongst three geographically remote and disconnected regions, in order to determine relationships amongst environmental data, variation in lichen secondary chemistry and microsatellite data in genotyped populations. In all, 928 Usnea thalli from 17 populations were genotyped using seven specific fungal microsatellite markers. Different measures of genetic diversity (allelic richness, private allelic richness, Nei’s unbiased genetic diversity and clonal diversity) were calculated and compared between lichen populations. Our results revealed a low genetic differentiation of U. subfloridana populations amongst three distant areas in Estonia and also a high level of gene flow. The results support suggestion of the long-range vegetative dispersal of subpendulous U. subfloridana via symbiotic propagules (soralia, isidia or fragments of thalli). Our study has also provided evidence that environmental variables, including mean annual temperature and geographical longitude, shape the genetic structure of U. subfloridana populations in Estonia. Additionally, a weak but statistically significant correlation between lichen chemotypes and microsatellite allele distribution was found in genotyped specimens.
- Published
- 2019
41. Climate change-induced range shift of the endemic epiphytic lichen Lobaria pindarensis in the Hindu Kush Himalayan region
- Author
-
Ram Prasad Chaudhary, Shiva Devkota, Lyudmyla Dymytrova, Christoph Scheidegger, and Silke Werth
- Subjects
0106 biological sciences ,010504 meteorology & atmospheric sciences ,Range (biology) ,Global warming ,Species distribution ,Biodiversity ,Climate change ,010603 evolutionary biology ,01 natural sciences ,Geography ,Habitat destruction ,Habitat ,Effects of global warming ,Physical geography ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences - Abstract
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 the distribution of the tripartite epiphytic macrolichen Lobaria pindarensis, considered to be endemic to the Himalayas. To predict the current and future distribution of this species we applied the Random Forest modelling algorithm and climatic variables with a post-processing of projected distributions using a map of habitat types in the study region. We calibrated models based on 1397 species presences within an altitudinal range of 2036–4000 m and extrapolated them according to two IPCC scenarios of climate change (RCP 2·6 and RCP 8·5). Based on the results of ensemble modelling, two new localities where L. pindarensis might potentially occur were predicted. Our simulations predicted a range expansion of this epiphytic lichen to the north-east and to higher altitudes in response to climate change, although the species’ low dispersal abilities and the local availability of trees as a substratum will considerably limit latitudinal and altitudinal shifts. By contrast, assuming the species can migrate to previously unoccupied areas, and depending on different future climate scenarios, our models forecasted a habitat loss of 30–70% for L. pindarensis. The main reason for the simulated habitat loss is the expected increase in mean annual temperature (by 1·5–3·7 °C) and total annual precipitation (by 56–125 mm). Our results contribute further evidence for the high sensitivity of tripartite macrolichens, especially those from mountain areas, to climate change and particularly emphasize the vulnerability of L. pindarensis. Thus, we stress the need to develop and formulate conservation measures and strategies for the protection of this endemic species in the Hindu Kush Himalayan region.
- Published
- 2019
42. Variation in Plant Functional Traits along Altitudinal Gradient and Land Use Types in Sagarmatha National Park and Buffer Zone, Nepal
- Author
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Krishna Kumar Shrestha, Srijana Shah, and Christoph Scheidegger
- Subjects
0106 biological sciences ,Ecology ,National park ,Stolon ,04 agricultural and veterinary sciences ,General Medicine ,Biology ,01 natural sciences ,Twig ,Disturbance (ecology) ,Grazing ,040103 agronomy & agriculture ,Litter ,0401 agriculture, forestry, and fisheries ,Trampling ,Transect ,010606 plant biology & botany - Abstract
Functional traits are predictors of plants in response to environmental stimuli. They represent specific functional adaptations to various environmental stresses. This study deals with the variation in plant functional traits along elevation gradient and land-use types in Sagarmatha National Park and Buffer Zone, Nepal. Two field investigations in April and September, 2011 were made to collect samples. Sampling was done from 2200 - 3800 m asl varying approx. 400 m. East and west facing aspects of each valley were chosen. In each aspect four land-use type categories including disturbed (cultivated land, exploited forest and meadow) and less disturbed natural forest were selected. A transect of 25 m long and 2.5 m wide was laid. Different eight traits of plants including lifeform, plant height, clonality, spinescence, leaf dry matter content, stem specific density, twig dry matter content and twig drying time were examined for 60 plant species belonging to 31 families, collected from 40 sampled plots. Nine different types of growth forms were recorded. Plant height of the investigated species ranged from 0.03 - 15 m. The stolon consisting species were dominant in exploited forests. Diversity of clonal species was more in meadow and non-clonal species were dominant in all the altitudes. Only eight species consisted of spines. In the disturbed land-use categories, we found high variation in a particular trait. Correlation analyses revealed the significant relationship (p < 0.01) among different traits. Herbs and shrubs were dominant at higher elevation and in disturbed land-use categories. Species from high altitude were mostly short basal herbs, while spinescence and tall trees were observed at lower altitudes. Species recorded in meadows and exploited forests showed high variation in traits due to disturbance mainly grazing, fire, litter collection and trampling. Altitudinal variation, climatic conditions and disturbance most strongly influence trait expression in the study area.
- Published
- 2019
43. New species and records of Pyxine (Caliciaceae) in China
- Author
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An-Cheng Yin, Dong Liu, Mei-Xia Yang, Yan Yun Zhang, Xin Yu Wang, Li Juan Li, Li-Song Wang, and Christoph Scheidegger
- Subjects
0106 biological sciences ,0301 basic medicine ,China ,Asia ,Pyxine ,Lichexanthone ,phylogeny ,010603 evolutionary biology ,01 natural sciences ,Lichenized Fungi ,03 medical and health sciences ,Meteora ,Stipe (botany) ,Ascomycota ,Pezizomycetes ,lichenised fungi ,lcsh:Botany ,Botany ,Unikonta ,Physciaceae ,Ecology, Evolution, Behavior and Systematics ,Taxonomy ,new species ,Palavascia ,biology ,Fungi ,Synchytriales ,Caliciaceae ,Schizosaccharomycetes ,030108 mycology & parasitology ,biology.organism_classification ,lcsh:QK1-989 ,Ascocarp ,Key (lock) ,Teloschistales ,Lecanoromycetes ,Population Genetics ,Research Article ,Lecanoromycetidae - Abstract
In this study, the diversity of Pyxine Fr. in China was assessed based on morphological and chemical traits and molecular data are inferred from ITS and mtSSU sequences. Nineteen species were recognised, including three that are new to science (i.e. P.flavicans M. X. Yang & Li S. Wang, P.hengduanensis M. X. Yang & Li S. Wang and P.yunnanensis M. X. Yang & Li S. Wang) and three records new to China were found (i.e. P.cognata Stirt., P.himalayensis Awas. and P.minuta Vain.). Pyxineyunnanensis is diagnosed by the small size of the apothecia, a white medulla of the stipe and the presence of lichexanthone. Pyxineflavicans is characterised by broad lobes, a pale yellow medulla of the stipe and the presence of atranorin. Pyxinehengduanensis can be distinguished by its pale yellow medulla, marginal labriform soralia and the absence of atranorin. Detailed descriptions of each new species are presented, along with a key to the known species of Pyxine in China.
- Published
- 2019
44. Are species-pairs diverging lineages? A nine-locus analysis uncovers speciation among species-pairs of the Lobaria meridionalis-group (Ascomycota)
- Author
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Christoph Scheidegger, Svetlana Chabanenko, and Carolina Cornejo
- Subjects
0106 biological sciences ,0301 basic medicine ,Time Factors ,Pleistocene ,Genetic Speciation ,Locus (genetics) ,Biology ,010603 evolutionary biology ,01 natural sciences ,03 medical and health sciences ,Monophyly ,Ascomycota ,Species Specificity ,Lobaria ,Genetics ,Lichen ,Endemism ,Molecular Biology ,Phylogeny ,Ecology, Evolution, Behavior and Systematics ,Geography ,Asia, Eastern ,Reproduction ,Sequence Analysis, DNA ,15. Life on land ,biology.organism_classification ,Genetics, Population ,030104 developmental biology ,Habitat destruction ,Genetic Loci ,Sympatric speciation ,Evolutionary biology ,Microsatellite Repeats - Abstract
In spite of considerable effort to verify the theory of species-pairs, uncertainty still exists about the relationship between sexually or vegetatively reproducing populations of morphologically indistinguishable, sympatric lichen species. The current paper studies putative species-pairs within the Asian Lobaria meridionalis-group, using a nine-locus and time calibrated species-tree approach. Analyses demonstrate that pairs of sexually or vegetatively reproducing lineages split into highly supported monophyletic clades—confirming molecularly the species-pair concept for the L. meridionalis-group. In the broader context of evolution and speciation dynamics in lichenized fungi, this paper attempts to synthesize molecular findings from the last two decades to promote a more modern perception of the species-pair concept. Taxonomically, eight species were found to currently conform to the L. meridionalis-group, which differentiated during the Pliocene and Pleistocene. The coincidence of paleoclimatic events with estimated dates of divergence support a bioclimatic hypothesis for the evolution of species in the L. meridionalis-group, which also explains their current eco-geographic distribution patterns. Greater recognition for species with a long and independent evolutionary history, which merit high conservation priority, will be especially critical for preserving geographically restricted endemics from Southeast Asia, where habitat loss is driving rapid declines.
- Published
- 2018
45. A hierarchical approach linking hydraulic and ecological modeling for habitat predictions for riverine pioneer vegetation
- Author
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Erik van Rooijen, Davide Vanzo, David Vetsch, Sabine Fink, Christoph Scheidegger, and Annunziato Siviglia
- Subjects
Habitat ,Ecology ,Ecosystem model ,medicine ,Environmental science ,medicine.symptom ,Vegetation (pathology) - Abstract
The distribution of sessile riparian plant species and their habitats along riverways are highly dependent on river dynamics and connectivity. River restoration and conservation of riparian plant species rely on expert knowledge and more recently also on modelling approaches to predict species’ occurrence. Ecological modelling on habitat suitability for terrestrial species is usually based on climatic and topographic features, whilst river hydrodynamics is rarely considered.Our study aims at predicting suitable habitat for a characteristic pioneer species for dynamic riverine habitats, the German Tamarisk (Myricaria germanica). Habitat predictions are tested in a case study on a floodplain along Moesa river in canton Grisons in South-East Switzerland. We link two modeling approaches having two different spatial scales using a hierarchical process. First, we define a large-scale habitat suitability matrix based on climatic, geological and topographic predictors. Using a two-dimensional hydrodynamic model, inundation frequency maps and flood level maps for several significant months for German Tamarisk establishment are constructed, to further refine the niche for the riparian plant.The predicted habitat suitability is evaluated with species presence data for both adult and offspring plants. Our results allow gaining insights into the importance of linking ecological and hydraulic models having different spatial and temporal scales, for more refined predictions of riparian species distribution.
- Published
- 2021
46. Phylogeographic reconstructions can be biased by ancestral shared alleles: The case of the polymorphic lichen Bryoria fuscescens in Europe and North Africa
- Author
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David L. Hawksworth, Víctor J. Rico, Carlos G. Boluda, Yamama Naciri, and Christoph Scheidegger
- Subjects
Lichens ,Lichen ecology ,Speciation ,Biology ,Coalescent theory ,Soredia ,Genetics ,Climate change ,Lichen ,Alleles ,Phylogeny ,Ecology, Evolution, Behavior and Systematics ,Isolation by distance ,Panmixia ,Genetic diversity ,Bioindicator ,Parmeliaceae ,Genetic Variation ,Europe ,Phylogeography ,ddc:580 ,Evolutionary biology ,Lichenicolous ,Biological dispersal ,Gene pool ,Microsatellite Repeats - Abstract
Large phylogeographic studies on lichens are scarce, and none involves a single species within which different lineages show fixed alternative dispersal strategies. We investigated Bryoria fuscescens (including B. capillaris) in Europe and western North Africa by phenotypically characterizing 1400 specimens from 64 populations and genotyping them with 14 microsatellites. We studied population structure and genetic diversity at the local and continental scales, discussed the post-glacial phylogeography, and compared dispersal capacities of phenotypes with and without soralia. Our main hypothesis is that the estimated phylogeography, migration routes, and dispersal capacities may be strongly biased by ancestral shared alleles. Scandinavia is genetically the richest area, followed by the Iberian Peninsula, the Carpathians, and the Alps. Three gene pools were detected: two partially linked to phenotypic characteristics, and the third one genetically related to the American sister species B. pseudofuscescens. The comparison of one gene pool producing soredia and one not, suggested both as panmictic, with similar levels of isolation by distance (IBD). The migration routes were estimated to span from north to south, in disagreement with the assessed glacial refugia. The presence of ancestral shared alleles in distant populations can explain the similar IBD levels found in both gene pools while producing a false signal of panmixia, and also biasing the phylogeographic reconstruction. The incomplete lineage sorting recorded for DNA sequence loci also supports this hypothesis. Consequently, the high diversity in Scandinavia may rather come from recent immigration into northern populations than from an in situ diversification. Similar patterns of ancestral shared polymorphism may bias the phylogeographical reconstruction of other lichen species.
- Published
- 2021
47. Hypotrachyna nepalensis (Taylor) Divakar, A. Crespo, Sipman, Elix & Lumbsch Parmeliaceae
- Author
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Christoph Scheidegger and Shiva Devkota
- Subjects
Geography ,biology ,Parmeliaceae ,Botany ,biology.organism_classification ,Hypotrachyna - Published
- 2021
48. Low genetic differentiation between apotheciate Usnea florida and sorediate Usnea subfloridana (Parmeliaceae, Ascomycota) based on microsatellite data
- Author
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Tiina Randlane, Andrei Tsurykau, Kristiina Mark, Dmitry E. Himelbrant, Polina Degtjarenko, Christoph Scheidegger, Irina S. Stepanchikova, and Rolands Moisejevs
- Subjects
biology ,Parmeliaceae ,Bayes Theorem ,Interspecific competition ,biology.organism_classification ,Infectious Diseases ,Taxon ,Usnea ,Evolutionary biology ,Principal component analysis ,Threatened species ,Genetics ,Microsatellite ,Conservation biology ,Lichen ,Ecology, Evolution, Behavior and Systematics ,Phylogeny ,Microsatellite Repeats - Abstract
Accurate species delimitation has a pivotal role in conservation biology, and it is especially important for threatened species where decisions have political and economic consequences. Finding and applying appropriate character sets and analytical tools to resolve interspecific relationships remains challenging in lichenized fungi. The main aim of our study was to re-assess the species boundaries between Usnea subfloridana and Usnea florida, which have been phylogenetically indistinguishable until now, but are different in reproductive mode and ecological preferences, using fungal-specific simple sequence repeats (SSR), i.e. microsatellite markers. Bayesian clustering analysis, discriminant analysis of principal components (DAPC), minimal spanning network (MSN), and principal component analysis (PCA) failed to separate U. florida and U. subfloridana populations. However, a low significant differentiation between the two taxa was observed across all populations according to AMOVA results. Also, analysis of shared haplotypes and statistical difference in clonal diversity (M) supported the present-day isolation between the apotheciate U. florida and predominantly sorediate U. subfloridana. Our results do not provide a clear support either for the separation of species in this pair or the synonymization of U. florida and U. subfloridana. We suggest that genome-wide data could help resolve the taxonomic question in this species pair.
- Published
- 2020
49. Effects of barriers on functional connectivity of riparian plant habitats under climate change
- Author
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Christoph Scheidegger and Sabine Fink
- Subjects
0106 biological sciences ,Ecological niche ,geography ,Environmental Engineering ,geography.geographical_feature_category ,Ecology ,010604 marine biology & hydrobiology ,fungi ,Species distribution ,Climate change ,Plant community ,Management, Monitoring, Policy and Law ,010603 evolutionary biology ,01 natural sciences ,Life history theory ,Habitat ,Environmental science ,Biological dispersal ,Nature and Landscape Conservation ,Riparian zone - Abstract
Alterations of riparian areas of running waters resulted in fragmentation of the riverscape. The possible impact of climate change additionally stresses the importance for conservation planning for riparian habitats, especially for sessile plant species. The survival of species under changing habitat availability can be counteracted by ensuring functional connectivity of riparian plant species. This study applies a coupled modelling framework using species distribution models and dispersal simulations, which allow to analyze the potential future distribution of species in relation to their ecological niche, life history traits including dispersal abilities as well as barriers to dispersal such as dams. Modelled suitable habitats for six riparian plant species characteristic for the olive willow plant community (Salicion elaeagni) showed dramatic changes under the impact of two climate change scenarios. While habitat suitability remained low for species with a narrow ecological niche, it increased under climate change scenarios for species which are also found in secondary habitat outside riparian areas. Simulations of dispersal to the potential future habitat revealed nevertheless high numbers of decolonized cells after 80 years of dispersal for species with high future habitat suitability. This stresses the importance of a joint investigation of the habitat suitability under climate change scenarios, dispersal parameters as well as life history traits for conservation planning of riparian species. The simulated future distribution revealed that barriers along rivers have a significant negative effect on the spread of the studied plant species. Our results suggest that conservation management should focus on providing connected stepping stone habitats for riparian plant species along rivers, as current species occurrences are not persistent over time.
- Published
- 2018
50. Estimating the timescale of Lobaria diversification
- Author
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Carolina Cornejo and Christoph Scheidegger
- Subjects
0106 biological sciences ,0301 basic medicine ,03 medical and health sciences ,030104 developmental biology ,biology ,Ecology ,Lobaria ,Diversification (finance) ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Ecology, Evolution, Behavior and Systematics - Abstract
Using an ITS mutation rate as calibration reference, a three-locus timetree was generated for the genus Lobaria and its most important clades. The timetree resolved most clades with strong support and gave an estimate of the diversification time for Lobaria during the early Oligocene. A fossil impression from a 12–24 million-year-old Miocene deposit is hypothesized here to belong to an ancestral Lobaria species. Additionally, the age estimate indicates that the paleoclimate and the closing or opening of the Bering Strait played a major role in shaping the current distribution of most Lobaria species. It is hypothesized that the Bering land bridge acted as a major highway during warm-temperate climate periods, but as a barrier during Arctic climate times.
- Published
- 2018
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