1,721,221 research outputs found
Genetic diversity and photobiont associations in selected taxa of the Tephromela atra group (Lecanorales, lichenized Ascomycota)
No full textNiches 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
A combined molecular and morphological approach to species delimitation in black-fruited, endolithic Caloplaca : high genetic and low morphological diversity
No full textA revision based on the morphological and genetic analyses of 133 specimens of black-fruited, endolithic Caloplaca belonging to subgenus Pyrenodesmia is presented. The material was collected in 16 sites distributed along a transept from Gargano (Central Italy) to the southeastern Alps, from sea level to ca 1500 m. The nuclear ITS was sequenced for all themycobionts and selected representatives of photobionts. Except for the sorediate C. erodens, all species share the same algal lineage of Trebouxia as photobiont. The haplotype analysis of the mycobionts revealed an unexpected, high genetic heterogeneity. Three main morphotypic clusters were recognized among five species [C. albopruinosa (syn. C. agardhiana auct.), C. alociza, C. badioreagens, C. erodens, and C. variabilis]. A phylogenetic analysis, including already available Caloplaca sequence data, revealed that these lichens form a monophyletic group within the genus. For each species, notes on ecology, distribution in Italy, and nomenclature are given
Caloplaca erodens [sect. Pyrenodesmia], a new lichen species from Italy with an unusual thallus type.
No full textAnalysis of the bacterial community associated with different species of lichens: preliminary results
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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