Phytogeny and evolution of Caliciaceae, Mycocaliciaceae, and Sphinctrinaceae (Ascomycota), with notes on the evolution of the prototunicate ascus

1997 ◽  
Vol 75 (8) ◽  
pp. 1236-1242 ◽  
Author(s):  
Mats Wedin ◽  
Leif Tibell

Small subunit ribosomal DNA has been sequenced from seven members of the ascomycete order Caliciales s.l. (Calicium adspersum, Cyphelium inquinans, Texosporium sancti-jacobi, and Thelomma mammosum (Caliciaceae), Chaenothecopsis savonica and Stenocybe pullatula (Mycocaliciaceae), and Sphinctrina turbinata (Sphinctrinaceae)), included in a matrix of 58 homologous ascomycete sequences and analysed with maximum parsimony analysis. The result shows the Caliciaceae to be a strongly supported monophyletic group within the Lecanorales s.l., although the jackknife support for a monophyletic Lecanorales is low. Mycocaliciaceae and Sphinctrinaceae form a well-supported monophyletic group, grouping with representatives of Eurotiales and Onygenales. This larger group is the sister group to Lecanorales, but the support for this sister-group relationship and the monophyly of the group consisting of Mycocaliciaceae–Sphinctrinaceae and Eurotiales–Onygenales is low. The evolution of the prototunicate ascus is discussed, and it is concluded that there is neither any evidence for a monophyletic Caliciales s.l., nor for the suggested group "Euascomycetideae" sensu Tehler, with the prototunicate Caliciales being the sister group to the rest of the true ascomycetes. Prototunicate asci are shown to have reappeared at least four times in the evolution of the ascomycetes. Key words: Ascomycetes, lichens, molecular evolution, phylogeny, ribosomal DNA, 18S rDNA.




Nematology ◽  
2003 ◽  
Vol 5 (5) ◽  
pp. 699-711 ◽  
Author(s):  
Peter Mullin ◽  
Timothy Harris ◽  
Thomas Powers

AbstractThe systematic position of Campydora Cobb, 1920, which possesses many unique morphological features, especially in pharyngeal structure and stomatal armature, has long been a matter of uncertainty with the 'position of the Campydorinae' (containing only Campydora) being questionable. A review of the morphology of C. demonstrans, the only nominal species of Campydora concluded that the species warranted placement as the sole member of a monotypic suborder, Campydorina, in the order Dorylaimida. Others placed Campydorina in the order Enoplida. We conducted phylogenetic analyses, using 18s small subunit ribosomal DNA sequences generated from a number of taxa in the subclasses Enoplia and Dorylaimia, to evaluate these competing hypotheses. Although precise taxonomic placement of the genus Campydora and the identity of its closest living relatives is in need of further investigation, our analyses, under maximum parsimony, distance, and maximum likelihood criteria, unambiguously indicate that Campydora shares a common, more recent, ancestry with genera such as Alaimus, Pontonema, Tripyla and Ironus (Enoplida), rather than with any members of Dorylaimida, Mononchida or Triplonchida.





2020 ◽  
Vol 8 (3) ◽  
pp. 316 ◽  
Author(s):  
Yurui Wang ◽  
Yaohan Jiang ◽  
Yongqiang Liu ◽  
Yuan Li ◽  
Laura A. Katz ◽  
...  

While nuclear small subunit ribosomal DNA (nSSU rDNA) is the most commonly-used gene marker in studying phylogeny, ecology, abundance, and biodiversity of microbial eukaryotes, mitochondrial small subunit ribosomal DNA (mtSSU rDNA) provides an alternative. Recently, both copy number variation and sequence variation of nSSU rDNA have been demonstrated for diverse organisms, which can contribute to misinterpretation of microbiome data. Given this, we explore patterns for mtSSU rDNA among 13 selected ciliates (representing five classes), a major component of microbial eukaryotes, estimating copy number and sequence variation and comparing to that of nSSU rDNA. Our study reveals: (1) mtSSU rDNA copy number variation is substantially lower than that for nSSU rDNA; (2) mtSSU rDNA copy number ranges from 1.0 × 104 to 8.1 × 105; (3) a most common sequence of mtSSU rDNA is also found in each cell; (4) the sequence variation of mtSSU rDNA are mainly indels in poly A/T regions, and only half of species have sequence variation, which is fewer than that for nSSU rDNA; and (5) the polymorphisms between haplotypes of mtSSU rDNA would not influence the phylogenetic topology. Together, these data provide more insights into mtSSU rDNA as a powerful marker especially for microbial ecology studies.



2008 ◽  
Vol 276 (1655) ◽  
pp. 239-245 ◽  
Author(s):  
Moriya Ohkuma ◽  
Satoko Noda ◽  
Yuichi Hongoh ◽  
Christine A Nalepa ◽  
Tetsushi Inoue

Cryptocercus cockroaches and lower termites harbour obligate, diverse and unique symbiotic cellulolytic flagellates in their hindgut that are considered critical in the development of social behaviour in their hosts. However, there has been controversy concerning the origin of these symbiotic flagellates. Here, molecular sequences encoding small subunit rRNA and glyceraldehyde-3-phosphate dehydrogenase were identified in the symbiotic flagellates of the order Trichonymphida (phylum Parabasalia) in the gut of Cryptocercus punctulatus and compared phylogenetically to the corresponding species in termites. In each of the monophyletic lineages that represent family-level groups in Trichonymphida, the symbionts of Cryptocercus were robustly sister to those of termites. Together with the recent evidence for the sister-group relationship of the host insects, this first comprehensive study comparing symbiont molecular phylogeny strongly suggests that a set of symbiotic flagellates representative of extant diversity was already established in an ancestor common to Cryptocercus and termites, was vertically transmitted to their offspring, and subsequently became diversified to distinct levels, depending on both the host and the symbiont lineages.



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