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Novel Sequence Discovery by Subtractive Genomics
Published on: January 25, 2019
Phylogenetic studies in the Candelariaceae (lichenized Ascomycota) based on nuclear ITS DNA sequence data
Martin Westberg1, Ulf Arup, Ingvar Kärnefelt
1Department of the Biological Museums, Lund University, Botanical Museum, Ostra Vallgatan 18, SE-223 61 Lund, Sweden. Martin.Westberg@botmus.lu.se
Mycological Research
|November 17, 2007
Summary
Phylogenetic analysis of the Candelariaceae lichen family reveals polyspored asci evolved limited times. The study clarifies relationships within Candelariella and suggests Candelaria may be polyphyletic.
Area of Science:
- Mycology
- Lichenology
- Molecular Phylogenetics
Background:
- The Candelariaceae family, characterized by its distinctive yellow lichens, lacks a well-defined phylogenetic framework.
- Previous taxonomic classifications relied heavily on morphological traits, which can be ambiguous in lichens.
Purpose of the Study:
- To investigate the evolutionary relationships within the lichen family Candelariaceae using molecular data.
- To clarify the phylogenetic positions of genera such as Candelariella, Candelaria, Candelina, and Placomaronea.
Main Methods:
- Phylogenetic analyses were conducted using nucleotide sequences from the Internal Transcribed Spacer (ITS) region of the nuclear ribosomal DNA (nu-rDNA).
- Maximum Parsimony (MP) and Bayesian Markov Chain Monte Carlo (MCMC) inference methods were employed.
- A broad sampling of 23 Candelariella, 6 Candelaria, 2 Candelina, and 2 Placomaronea species was included, with Acarospora cervina and Pleopsidium chlorophanum as outgroups.
Main Results:
- Phylogenetic trees showed poor resolution overall, with strong support only for terminal clades.
- Polyspored asci appear to have evolved a limited number of times within the family, present in four distinct clades.
- The core Candelariella group, including C. vitellina, formed a distinct clade.
- Placomaronea and Candelina generated strongly supported monophyletic clades, but their generic boundaries and relationships to Candelariella remain unclear.
- The genus Candelaria is likely polyphyletic, suggesting a potential revision to include only polyspored species with a lower cortex.
Conclusions:
- Molecular data provide insights into the evolution of key traits like polyspored asci within Candelariaceae.
- The study highlights the need for further taxonomic revision of genera like Candelaria, Candelina, and Placomaronea based on molecular evidence.
- Morphological characters alone are insufficient for resolving the complex evolutionary history of this lichen family.
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