Oscar Blanco

Bio: Oscar Blanco is an academic researcher from Complutense University of Madrid. The author has contributed to research in topics: Parmeliaceae & Monophyly. The author has an hindex of 18, co-authored 22 publications receiving 1457 citations.

Phylogenetic generic classification of parmelioid lichens (Parmeliaceae, Ascomycota) based on molecular, morphological and chemical evidence

Abstract: Parmelioid lichens are a diverse and ubiquitous group of foliose lichens. Generic delimitation in parmelioid lichens has been in a state of flux since the late 1960s with the segregation of the large, heterogeneous genus Parmelia into numerous smaller genera. Recent molecular phylogenetic studies have demonstrated that some of these new genera were monophyletic, some were not, and others, previously believed to be unrelated, fell within single monophyletic groups, indicating the need for a revision of the generic delimitations. This study aims to give an overview of current knowledge of the major clades of all parmelioid lichens. For this, we assembled a dataset of 762 specimens, including 31 of 33 currently accepted parmelioid genera (and 63 of 84 accepted genera of Parmeliaceae). We performed maximum likelihood and Bayesian analyses of combined datasets including two, three and four loci. Based on these phylogenies and the correlation of morphological and chemical characters that characterize monophyletic groups, we accept 27 genera within nine main clades. We re-circumscribe several genera and reduce Parmelaria to synonymy with Parmotrema. Emodomelanelia Divakar & A. Crespo is described as a new genus (type: E. masonii). Nipponoparmelia (Kurok.) K.H. Moon, Y. Ohmura & Kashiw. ex A. Crespo & al. is elevated to generic rank and 15 new combinations are proposed (in the genera Flavoparmelia, Parmotrema, Myelochroa, Melanelixia and Nipponoparmelia). A short discussion of the accepted genera is provided and remaining challenges and areas requiring additional taxon sampling are identified.

A molecular phylogeny and a new classification of parmelioid lichens containing Xanthoparmelia-type lichenan (Ascomycota: Lecanorales)

Abstract: Generic concepts in the parmelioid lichens have been discussed intensively over the past three decades without reaching a broad consensus. We have now employed molecular data from three genes to provide a basis for a revised generic concept of the parmelioid lichens containing Xanthoparmelia-type lichenan. The phylogeny of the parmelioid lichens containing Xanthoparmelia-type lichenan was reconstructed using a combined Bayesian analysis of nuclear ITS, LSU rDNA and mitochondrial SSU rDNA sequences, and a maximum parsimony analysis was also made for comparison. 179 new partial sequences of 58 taxa were generated and 12 sequences were downloaded from GenBank. Our results indicate that the lichens containing Xanthoparmelia-type lichenan form a monophyletic group. However, the segregates proposed earlier do not form distinct clades within the group. Alternative hypotheses of monophyletic Karoowia and Neofuscelia that are not nested within Xanthoparmelia were rejected with our dataset; Karoowia is polyphyletic, and Neofuscelia is reduced to synonymy under Xanthoparmelia. Xanthomaculina convoluta also belongs to Xanthoparmelia. Since we were unable to sequence the umbilicate type species ofXanthomaculina, we refrain from synonymizing that genus with Xanthoparmelia here. The synonymy of Chondropsis and Paraparmelia under Xanthoparmelia already proposed is supported. The revised and enlarged genus Xanthoparmelia includes species that have cell walls with Xanthoparmelia-type lichenan, a palisade plectenchyma with a pored epicortex, lack pseudocyphellae, with usually simple rhizines, generally bifusiform conidia, and medullary chemical diversity. Ten new names are proposed, and 129 new combinations are made into Xanthoparmelia.

The potential of mitochondrial DNA for establishing phylogeny and stabilising generic concepts in the parmelioid lichens

Abstract: A satisfactory resolution of the current instability of generic concepts in the parmelioid lichens, and particularly Parmelia s.l., has not so far emerged from molecular studies. The rDNA ITS sequence has proven too variable and the rDNA SSU too conserved to provide satisfactory discrimination around the family and generic levels in Parmeliaceae s.l. Studies of 31 new sequences of species belonging to 30 genera in the family (including the type species of 21) are reported here. These demonstrate that the mitochondrial DNA (mtDNA) SSU region has the potential to play a major role in establishing the phylogeny and stabilising generic concepts in some of the world's most conspicuous lichens. Some clades identified appear to correlate with differences in cell wall carbohydrates, epicortical, conidial, and other features. The emerging groupings now need to be further tested by the inclusion of sequences from additional genera and species. Nomenclatural changes should not be made until further work has been carried out.

Nuclear ribosomal internal transcribed spacer (ITS) region as a universal DNA barcode marker for Fungi

Abstract: Six DNA regions were evaluated as potential DNA barcodes for Fungi, the second largest kingdom of eukaryotic life, by a multinational, multilaboratory consortium. The region of the mitochondrial cytochrome c oxidase subunit 1 used as the animal barcode was excluded as a potential marker, because it is difficult to amplify in fungi, often includes large introns, and can be insufficiently variable. Three subunits from the nuclear ribosomal RNA cistron were compared together with regions of three representative protein-coding genes (largest subunit of RNA polymerase II, second largest subunit of RNA polymerase II, and minichromosome maintenance protein). Although the protein-coding gene regions often had a higher percent of correct identification compared with ribosomal markers, low PCR amplification and sequencing success eliminated them as candidates for a universal fungal barcode. Among the regions of the ribosomal cistron, the internal transcribed spacer (ITS) region has the highest probability of successful identification for the broadest range of fungi, with the most clearly defined barcode gap between inter- and intraspecific variation. The nuclear ribosomal large subunit, a popular phylogenetic marker in certain groups, had superior species resolution in some taxonomic groups, such as the early diverging lineages and the ascomycete yeasts, but was otherwise slightly inferior to the ITS. The nuclear ribosomal small subunit has poor species-level resolution in fungi. ITS will be formally proposed for adoption as the primary fungal barcode marker to the Consortium for the Barcode of Life, with the possibility that supplementary barcodes may be developed for particular narrowly circumscribed taxonomic groups.

Accounting for calibration uncertainty in phylogenetic estimation of evolutionary divergence times

Abstract: The estimation of phylogenetic divergence times from sequence data is an important component of many molecular evolutionary studies. There is now a general appreciation that the procedure of divergence dating is considerably more complex than that initially described in the 1960s by Zuckerkandl and Pauling (1962, 1965). In particular, there has been much critical attention toward the assumption of a global molecular clock, resulting in the development of increasingly sophisticated techniques for inferring divergence times from sequence data. In response to the documentation of widespread departures from clocklike behavior, a variety of local- and relaxed-clock methods have been proposed and implemented. Local-clock methods permit different molecular clocks in different parts of the phylogenetic tree, thereby retaining the advantages of the classical molecular clock while casting off the restrictive assumption of a single, global rate of substitution (Rambaut and Bromham 1998; Yoder and Yang 2000).

Basidiomycete yeasts in the cortex of ascomycete macrolichens

Abstract: For over 140 years, lichens have been regarded as a symbiosis between a single fungus, usually an ascomycete, and a photosynthesizing partner. Other fungi have long been known to occur as occasional parasites or endophytes, but the one lichen–one fungus paradigm has seldom been questioned. Here we show that many common lichens are composed of the known ascomycete, the photosynthesizing partner, and, unexpectedly, specific basidiomycete yeasts. These yeasts are embedded in the cortex, and their abundance correlates with previously unexplained variations in phenotype. Basidiomycete lineages maintain close associations with specific lichen species over large geographical distances and have been found on six continents. The structurally important lichen cortex, long treated as a zone of differentiated ascomycete cells, appears to consistently contain two unrelated fungi.

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