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Keywords: Cetraria aculeata/ Genetic diversity/ Global change/ Lichens/ Polar lichens/ Trebouxia jamesii
Abstract: Lichens, symbiotic associations of fungi (mycobionts) and green algae or cyanobacteria (photobionts), are poikilohydric organisms that are particularly well adapted to withstand adverse environmental conditions. Terrestrial ecosystems of the Antarctic are therefore largely dominated by lichens. The effects of global climate change are especially pronounced in the maritime Antarctic and it may be assumed that the lichen vegetation will profoundly change in the future. The genetic diversity of populations is closely correlated to their ability to adapt to changing environmental conditions and to their future evolutionary potential. In this study, we present evidence for low genetic diversity in Antarctic mycobiont and photobiont populations of the widespread lichen Cetraria aculeata. We compared between 110 and 219 DNA sequences from each of three gene loci for each symbiont. A total of 222 individuals from three Antarctic and nine antiboreal, temperate and Arctic populations were investigated. The mycobiont diversity is highest in Arctic populations, while the photobionts are most diverse in temperate regions. Photobiont diversity decreases significantly towards the Antarctic but less markedly towards the Arctic, indicating that ecological factors play a minor role in determining the diversity of Antarctic photobiont populations. Richness estimators calculated for the four geographical regions suggest that the low genetic diversity of Antarctic populations is not a sampling artefact. Cetraria aculeata appears to have diversified in the Arctic and subsequently expanded its range into the Southern Hemisphere. The reduced genetic diversity in the Antarctic is most likely due to founder effects during long-distance colonization. © 2012 S. Domaschke et al.
URL: http://dx.doi.org/10.3402/polar.v31i0.17353
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Abstract: [Genetic structure of mycobionts and photobionts were compared based on three loci for each symbiont, and found that "genetic variance of the photobiont is best explained by differentiation between temperate and polar regions and that of the mycobiont by an interaction of climatic and geographical factors."]
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Keywords: amphitropical disjunction/ Antarctica/ lichenized fungi/ Patagonia/ Pleistocene/ stochastic mapping
Abstract: Many boreal and polar lichens occupy bipolar distributional ranges that frequently extend into high mountains at lower latitudes. Although such disjunctions are more common among lichens than in other groups of organisms, the geographic origin of bipolar lichen taxa, and the way and time frame in which they colonized their ranges have not been studied in detail. We used the predominantly vegetative, widespread lichen Cetraria aculeata as a model species. We surveyed the origin and history of its bipolar pattern using population genetics, phylogenetic and genealogical reconstruction methods. Cetraria aculeata originated in the Northern Hemisphere and dispersed southwards during the Pleistocene. The genetic signal suggests a Pleistocene dispersive burst in which a population size expansion concurred with the acquisition of a South-American range that culminated in the colonization of the Antarctic. © 2013 Blackwell Publishing Ltd.
URL: http://dx.doi.org/10.1111/mec.12210
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Abstract: We describe three new, seemingly-cryptic species in the lichen genus Caloplaca (Teloschistaceae) with black apothecia. Those species, separated in nrITS and β-tubulin DNA phylogenies, appeared to be phenotypically indistinguishable. We looked for their phenotypic differences using a two-phase method comprised of a preliminary examination in which diagnostic value of all available characters was evaluated using a small number of samples and potentially-diagnostic characters were selected, and a subsequent detailed study in which characters selected in the first phase were tested using more samples. We found 19 diagnostic characters (continuous and discrete) of which four continuous and three discrete characters could be considered “fully diagnostic”, i.e. allowing for correct identification of at least one species. Hence, the three species are not cryptic, but can be distinguished phenotypically. Here, they are formally described as Caloplaca micromarina Frolov, Khodos. & Vondrák sp. nova, C. micromontana Frolov, Wilk & Vondrák sp. nova and C. microstepposa Frolov, Nadyeina, Khodos. & Vondrák sp. nova.
Notes: New: Caloplaca micromarina Frolov, Khodos. & Vondrák (from Russia, Turkey and Ukraine), C. micromontana Frolov, Wilk & Vondrák (from Austria, Pakistan, Poland, Russia, Slovakia), Caloplaca microstepposa Frolov, Nadyeina, Khodos. & Vondrák (from Austria, Bulgaria, Czech Republic, France, Germany, Italy, Kazakhstan, Poland, Russia, Serbia, Spain, Turkey, Ukraine).
URL: http://www.bioone.org/doi/full/10.5735/085.053.0413
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Keywords: Genetic diversity/ Tropical/ Alpine/ Adaptation/ NMDS/ Trebouxia
Abstract: Lichens represent an extremely successful symbiosis between fungi and photosynthetic partners. It has been suggested that lichens can enhance their adaptive potential and widen their ecological niches by associating with locally adapted photobionts. Based on a worldwide population sample of the lichen Cetraria aculeata we investigate the genetic diversity and composition of photobiont and mycobiont populations of this species with a special focus on tropical alpine regions that have never been studied before. Probably due to their geographic isolation and founder effects during colonization, tropical mycobiont populations display low genetical diversity. In sharp contrast, tropical photobiont populations are among the most diverse within the species and similar in composition to polar populations. These results support the hypothesis of photobiont switching as an adaptive strategy in lichens.
URL: http://link.springer.com/article/10.1007%2Fs13199-015-0351-1
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Abstract: Most lichen-forming fungi are characterized by the production of secondary metabolites. Differences in metabolite patterns have frequently served to distinguish lichen taxa with subsequent controversies about the rank of chemical variants (chemotype, variety, subspecies or species). Using a model system, we investigate whether production of norstictic acid within a group of lichenized ascomycetes is correlated with phylogenetic patterns, population differentiation or single and multi-locus haplotypes. Our study is based on DNA sequences of three gene loci (ITS, GPD, mtLSU) together with HPLC (311) and TLC (594) data from a total of 594 samples of three closely related fruticose lichens: Cetraria aculeata and C. muricata without norstictic acid, and C. steppae with norstictic acid. In nature, C. aculeata and C. steppae often occur together and the status of C. steppae as a separate species has been questioned. Our results show geographical but no phylogenetic structure of norstictic acid production and few significant associations between genetic clusters and the occurrence of norstictic acid. All frequently distributed haplotypes display differences in norstictic acid content. The few associations at the population level are most likely a by-product of spatial genetic structure, because norstictic acid was expressed only in individuals from the Mediterranean-Central Asian part of the study area. We conclude that the production of norstictic acid in the C. aculeata group is most likely triggered by the environment (climate, edaphic factors, associated symbionts). Cetraria steppae might be a different evolutionary lineage restricted to warm temperate regions but it is not uniquely characterized by the presence of norstictic acid.
URL: https://www.cambridge.org/core/product/3516CB36666202430C62EAAC2AEFF912
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Abstract: All fungi in the class Lichinomycetes are lichen-forming and exclusively associate with cyanobacteria. Two closely related maritime species of the genus Lichina (L. confinis and L. pygmaea) show similar distribution ranges in the Northeast Atlantic, commonly co-occurring at the same rocky shores but occupying different littoral zones. By means of 16S rRNA and phycocyanin operon markers we studied a) the phylogenetic relationships of cyanobionts associated with these species, b) the match of divergence times between both symbionts, and c) whether Lichina species differ in photobiont association and in how geography and ecology affect selectivity. The cyanobionts studied are closely related to both marine and freshwater strains of the genus Rivularia. We found evidence of a high specificity to particular cyanobiont lineages in both species: Lichina pygmaea and L. confinis incorporate specific lineages of Rivularia that do not overlap at the haplotype nor the OTU levels. Dating divergences of the fungal and cyanobacterial partners revealed an asynchronous origin of both lineages. Within each fungal species, selectivity varied across the studied area, influenced by environmental conditions (both atmospheric and marine), although patterns were highly correlated between both lichen taxa. Ecological speciation due to the differential association of photobionts to each littoral zone is suspected to have occurred in marine Lichina.
URL: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0132718
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Keywords: Ascomycota/ Cetraria aculeata/ Diffuse-intercalary growth/ lichens/ phenotypic variability/ spatial disturbance/ ultrastructure
Abstract: Background and Aims: Phenotypic variability is a successful strategy in lichens for colonizing different habitats. Vagrancy has been reported as a specific adaptation for lichens living in steppe habitats around the world. Among the facultatively vagrant species, the cosmopolitan Cetraria aculeata apparently forms extremely modified vagrant thalli in steppe habitats of Central Spain. The aim of this study was to investigate whether these changes are phenotypic plasticity (a single genotype producing different phenotypes), by characterizing the anatomical and ultrastructural changes observed in vagrant morphs, and measuring differences in ecophysiological performance. Methods: Specimens of vagrant and attached populations of C. aculeata were collected on the steppes of Central Spain. The fungal internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GPD) and the large sub-unit of the mitochondrial ribosomal DNA (mtLSUm), and the algal ITS and actin were studied within a population genetics framework. Semi-thin and ultrathin sections were analysed by means of optical, scanning electron and transmission electron microscopy. Gas exchange and chlorophyll fluorescence were used to compare the physiological performance of both morphs. Key Results: and Conclusions: Vagrant and attached morphs share multilocus haplotypes which may indicate that they belong to the same species in spite of their completely different anatomy. However, differentiation tests suggested that vagrant specimens do not represent a random sub-set of the surrounding population. The morphological differences were related to anatomical and ultrastructural differences. Large intercalary growth rates of thalli after the loss of the basal-apical thallus polarity may be the cause of the increased growth shown by vagrant specimens. The anatomical and morphological changes lead to greater duration of ecophysiological activity in vagrant specimens. Although the anatomical and physiological changes could be chance effects, the genetic differentiation between vagrant and attached sub-populations and the higher biomass of the former show fitness effects and adaptation to dry environmental conditions in steppe habitats. © 2012 The Author.
URL: http://dx.doi.org/10.1093/aob/mcs042
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Keywords: Alphaproteobacteria/ Cetraria aculeata/ Climate/ Diversity/ Lichens/ acid soil/ alpine environment/ bacterium/ climate change/ geographical distribution/ lichen/ microbial community/ species diversity/ symbiosis/ Acetobacteraceae/ algae/ Alphaproteobacteria/ Bacteria (microorganisms)/ Cetraria aculeata
Abstract: Lichen symbioses were recently shown to include diverse bacterial communities. Although the biogeography of lichen species is fairly well known, the patterns of their bacterial associates are relatively poorly understood. Here we analyse the composition of Alphaproteobacteria in Cetraria aculeata, a common lichen species that occurs at high latitudes and various habitats. Using clone libraries we show that most of the associated Alphaproteobacteria belong to Acetobacteraceae, which have also been found previously in other lichen species of acidic soils and rocks in alpine habitats. The majority of alphaproteobacterial sequences from C. aculeata are very similar to each other and form a single clade. Data from C. aculeata reveal that alphaproteobacterial communities of high latitudes are depauperate and more closely related to each other than to those of extrapolar habitats. This agrees with previous findings for the fungal and algal symbiont in this lichen. Similar to the algal partner, the composition of lichen alphaproteobacterial communities is affected by environmental parameters. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd.
URL: http://dx.doi.org/10.1111/j.1574-6941.2012.01358.x
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Keywords: SPAIN/ IBERIAN PENINSULA/ OPEGRAPHA/ ABSCONDITELLA
Abstract: [Notes on Absconditella lignicola and Opegrapha zwackhii.]
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Number of hits shown/total: 11/11.
Number of records in database: 53502.
Current date: 2024.04.19.OK