1,721,027 research outputs found
Niches and adaptation of polyextremotolerant black fungi.
No full textEnvironmental changes such as increased levels of carbon dioxide and UV radiation are usually perceived as a threat to living organisms and associated with shrinking populations and extinction. We frequently forget that some species cope really well with a range of extreme and rapidly changing conditions and may actually benefit from such changes. Black meristematic fungi, for example, are well adapted to high doses of radiation and survive long periods of desiccation. They seem not only robust under moderate stress conditions but seem to adapt and diversify, in agreement with the so-called concept of antifragility. We hypothesise that this behaviour is mediated by the polymer melanin in the cell walls; yet, other protective molecules and phenotypic plasticity play an important role as well. Evolution of these fungi is thought to have originated in the harsh oligotrophic habitats on the surface and subsurface of rocks, but their potentials are much wider than that. Their polyextremotolerance helps them to colonise numerous habitats in which competition with other fungi is low due to stressful conditions. This includes a range of anthropogenic environments and in some cases also animal bodies. Some of these fungi also undergo lichen-like associations with photoautotrophs or benefit from growing on lichens
Relevance of plant and fungal DNA metabarcoding in aerobiology
No full textAerobiology studies biological particles present in the air of both indoor and outdoor environments. In the past few years, the application of molecular techniques has considerably improved the knowledge of organismal diversity in air samples and highlighted its ecological and clinical importance. DNA metabarcoding in particular has been recently applied worldwide to describe the biological composition of airborne bacteria, fungi and plants. Here, we provide a comprehensive overview of those aerobiology studies which, in the past few years, have applied DNA metabarcoding techniques. We focus specifically on researches including plants and fungi and review the multiplicity of experimental plans, sampling procedures, laboratory processing methods, the choice of the DNA barcode(s), the selection of sequencing platforms and bioinformatics pipelines for the comparability of data obtained from multiple origins
Fruticose lichen communities at the edge: distribution and diversity in a desert sky island on the Colorado Plateau
Full text linkSubalpine habitats in sky islands in the Southwestern USA are currently facing largescale transformations. Lichens have widely been used as bioindicators of environmental change.
On the Colorado Plateau, fruticose lichens occur in patchy, disconnected populations, including
unique lichen-draped conifer sites in subalpine forests in the La Sal Mountains in southeastern Utah.
Here, we document the distribution and fungal diversity within these lichen communities. We find
that lichen-draped conifer sites in the La Sal Mountains are restricted to only three known, small
areas in Picea englemannii forests above 3000 m above sea level, two of which have recently been
impacted by wildfire. We document 30 different species of lichen-forming fungi in these communities,
several which represent the first reports from the Colorado Plateau. We also characterize mycobiont
haplotype diversity for the fruticose lichens Evernia divaricata, Ramalina sinensis, and multiple Usnea
species. We also report a range of diverse fungi associated with these lichens, including genetic
clusters representing 22 orders spanning seven classes of Ascomycetes and fewer clusters representing
Basidiomycetes. Our results provide a baseline for ongoing monitoring and help to raise awareness
of unique lichen communities and other biodiversity in the region
The plurality of photobionts within single lichen thalli
No full textPhotobiont plurality refers to the presence of multiple photobionts within a single lichen thallus. This phenomenon was
described at the end of the last century but has received deeper attention in the last decade. The available literature on this
topic is limited and studies address only a few groups of lichens. Here, the most recent and important findings on photobiont
plurality reported to date are revisited. The most commonly reported photobionts coexisting in a lichen thallus are algae of
the genus Trebouxia, though other algae and cyanobacteria more or less phylogenetically related may also coexist together.
A thallus with multiple photobionts may be formed at the beginning by the association of hyphae with several photobionts
at once or by the acquisition of additional photobionts during life. The most important factors affecting the cooccurrence
of multiple photobionts in a single thallus are likely the specificity and selectivity of mycobionts and local environmental
conditions. Photobiont plurality has been investigated so far in about fifty species of lichen-forming fungi among the
approximately 20,000 mycobiont species described. Coexisting photobionts differ in responses to several environmental,
mostly stress conditions, suggesting that the presence of multiple photobionts in a thallus may provide an advantage for
colonizing new habitats and may be essential for survival in localities with harsh or frequently changing conditions
Reassessing evolutionary relationships in Siplonema (Peltigerales, Lecanoromycetes)
No full textSpilonema was originally described to accommodate an unusual group of cyanolichens with thread-like, cushion-forming thalli, and has long been placed in Coccocarpiaceae based on ascomatal development. However, Spilonema is the only genus of Peltigerales to include species lichenized with the cyanobacterial genus Stigonema, and the evolutionary relationships of Spilonema to other genera in the family have yet to be tested using molecular data. We present evidence from combined nuclear 28S, 18S and mitochondrial 12S rDNA to confirm the placement of the core species of Spilonema (S. paradoxum and S. revertens) in Coccocarpiaceae. Our data further show that despite possessing a different genus of photobiont (Scytonema), the north Pacific endemic genus Spilonemella must be included within Spilonema, suggesting that closely related species of the genus have changed photobionts in the course of evolution. However, we recovered Spilonema dendroides, one of the only lichens known to associate with the cyanobacterial genus Hyphomorpha, as only distantly related to the Coccocarpiaceae. The evolutionary relationships of this species are as yet unclear but it may occupy a basal position in the Peltigerales. We create for this species the new genus Erinacellus T. Sprib., Muggia & Tønsberg
Macroecological diversification and convergence in a clade of keystone symbionts.
Full text linkLichens are classic models of symbiosis, and one of the most frequent nutritional modes among fungi. The ecologically and
geographically widespread lichen-forming algal (LFA) genus Trebouxia is one of the best-studied groups of LFA and
associates with over 7000 fungal species. Despite its importance, little is known about its diversification. We synthesized
twenty years of publicly available data by characterizing the ecological preferences of this group and testing for
time-variant shifts in climatic regimes over a distribution of trees. We found evidence for limited shifts among regimes, but
that disparate lineages convergently evolved similar ecological tolerances. Early Trebouxia lineages were largely forest
specialists or habitat generalists that occupied a regime whose extant members occur in moderate climates. Trebouxia then
convergently diversified in non-forested habitats and expanded into regimes whose modern representatives occupy
wet-warm and cool-dry climates. We rejected models in which climatic diversification slowed through time, suggesting
climatic diversification is inconsistent with that expected under an adaptive radiation. In addition, we found that climatic
and vegetative regime shifts broadly coincided with the evolution of biomes and associated or similar taxa. Together, our
work illustrates how this keystone symbiont from an iconic symbiosis evolved to occupy diverse habitats across the globe
Thallus Growth Stage and Geographic Origin Shape Microalgal Diversity in Ramalina farinacea Lichen Holobionts
Full text linkLichen symbioses are microecosystems hosting many other living organisms besides the two major lichen symbionts (i.e., lichenized fungi [the mycobiont] and green microalgae or cyanobacteria [the photobiont]). Recent investigations evidenced that other fungi, non-photosynthetic bacteria, and microalgae co-inhabit within the lichen thalli, but their diversity and their roles are still underinvestigated. Here we present an ad hoc stratified sampling design and in-depth Illumina paired-end metabarcoding approach to explore microalgal diversity in lichen thalli of the model species Ramalina farinacea from different ecologies. Lichen thalli were surveyed according to three different sizes, and different thallus parts were considered for molecular, bioinformatics, and community diversity analyses. The results revealed that microalgal diversity strongly depends on the growth stage of the thalli, the geographic area, and the habitat type. The results also show that microalgal diversity does not vary along the thallus branches (lacinias)—that is, it does not correlate with the apical growth and founder effects—and that there is no balanced co-presence of two main photobionts as previously established in R. farinacea. The sampling design performed here minimizes bias in the assessment of photobiont diversity in lichens and is proposed to be reliable and applicable to further study microalgal diversity in lichen symbioses
An overview of genomics, phylogenomics and proteomics approaches in ascomycota
Full text linkFungi are among the most successful eukaryotes on Earth: they have evolved strategies to survive in the most diverse environments and stressful conditions and have been selected and exploited for multiple aims by humans. The characteristic features intrinsic of Fungi have required evolutionary changes and adaptations at deep molecular levels. Omics approaches, nowadays including genomics, metagenomics, phylogenomics, transcriptomics, metabolomics, and proteomics have enormously advanced the way to understand fungal diversity at diverse taxonomic levels, under changeable conditions and in still under-investigated environments. These approaches can be applied both on environmental communities and on individual organisms, either in nature or in axenic culture and have led the traditional morphology-based fungal systematic to increasingly implement molecular-based approaches. The advent of next-generation sequencing technologies was key to boost advances in fungal genomics and proteomics research. Much effort has also been directed towards the development of methodologies for optimal genomic DNA and protein extraction and separation. To date, the amount of proteomics investigations in Ascomycetes exceeds those carried out in any other fungal group. This is primarily due to the preponderance of their involvement in plant and animal diseases and multiple industrial applications, and therefore the need to understand the biological basis of the infectious process to develop mechanisms for biologic control, as well as to detect key proteins with roles in stress survival. Here we chose to present an overview as much comprehensive as possible of the major advances, mainly of the past decade, in the fields of genomics (including phylogenomics) and proteomics of Ascomycota, focusing particularly on those reporting on opportunistic pathogenic, extremophilic, polyextremotolerant and lichenized fungi. We also present a review of the mostly used genome sequencing technologies and methods for DNA sequence and protein analyses applied so far for fungi
Forage quality improves but ecosystem multifunctionality declines under drought and frequent cutting in dry grassland mesocosms
No full textDry grasslands are vast, socioeconomically and ecologically important environments, which are increasingly threatened by multiple stressors. We tested whether plant cover composition could mitigate ecosystem services loss under multiple stressors in dry grassland mesocosms by growing the grass sorghum (Sorghum bicolor) alone (Grass cover) or together with the legume serradella (Ornithopus sativus) (Mixed cover) under frequent cutting and/or increasing water stress. We assessed erosion control, carbon sequestration, forage quantity and quality, and soil fertility, individually and simultaneously (i.e., multifunctionality). Contrary to our hypothesis, the Mixed cover did not improve ecosystem services compared to the Grass cover, except for forage quality, which improved by 30%. In general, the stressors had negative effects: cutting reduced erosion control by 20%, forage quantity by 50%, soil fertility by 40% and multifunctionality by 20%, and severe water stress decreased carbon sequestration by 40%, forage quantity by 30%, soil fertility by 10%, and multifunctionality by 10%. Water stress caused 100% serradella mortality, underscoring this legume’s vulnerability to increasing aridity. Combined stressors yielded the lowest service provision. Forage quality was the only service that improved under stress: cutting improved it by 40% and severe water stress by 60%. Our results suggest that while systems combining grasses and legumes may enhance forage quality, grass-dominated systems appear more resilient to multiple stressors in drylands, largely due to their superior efficiency in accessing and conserving limited water and nutrient resources. Given the ongoing trends of aridification and land-use intensification, future research should explore adaptive management strategies that prioritize resource-efficient plant species, foster belowground resource retention, and optimize grazing regimes to sustain resilience and multifunctionality in dry grasslands
Contrasting patterns of climatic niche divergence in Trebouxia—A alade of lichen-forming algae.
Full text linkLichen associations are overwhelmingly supported by carbon produced by photosynthetic algal symbionts. These algae have diversified to occupy nearly all climates and continents; however, we have a limited understanding of how their climatic niches have evolved through time. Here we extend previous work and ask whether phylogenetic signal in, and the evolution of, climatic niche, varies across climatic variables, phylogenetic scales, and among algal lineages in Trebouxia—the most common genus of lichen-forming algae. Our analyses reveal heterogeneous levels of
phylogenetic signal across variables, and that contrasting models of evolution underlie the evolution of climatic niche divergence. Together these analyses demonstrate the variable processes responsible for shaping climatic tolerance in Trebouxia, and provide a framework within which to better understand potential responses to climate change associated perturbations. Such predictions reveal a disturbing trend in which the pace at which modern climate change is proceeding will vastly exceed the rate at which Trebouxia climatic niches have previously evolved
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