Molecular systematics of Plicaria and Peziza (Pezizaceae: Ascomycetes): taxonomic implications and pattern of adaptation to postfire habitats

Norman, John E. (1995) Molecular systematics of Plicaria and Peziza (Pezizaceae: Ascomycetes): taxonomic implications and pattern of adaptation to postfire habitats. Masters thesis, Memorial University of Newfoundland.

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Abstract

Morphological similarity between Plicaria, which has spherical spores, and Peziza, which has elliptical spores, has lead to a great deal of disagreement over the recognition of Plicaria as a valid genus. The first objective of this study was to determine if Plicaria represented a phylogenetic grouping of taxa distinct from Peziza. Both taxa also show similarity in having adapted to occur in burned habitats following fires. The second component of this study was to compare the pattern of adaptation to burned habitats in Plicaria and Peziza. -- To determine the phylogenetic relationships of Plicaria to Peziza and selected members of Pezizaceae, DNA sequences were obtained from the Small Subunit (SSU) gene, 3’ Internal Transcribed Spacer region (ITS-1) and Large Subunit (LSU) gene of the nuclear-encoded ribosomal DNA. -- Parsimony analysis of nucleotide characters showed that Plicaria and elliptical-spored Peziza species with a similar suite of morphological characters (Plicaria-like-Peziza) formed a closely-related monophyletic group distinct from other Peziza species. This makes Peziza paraphyletic, which can be dealt with by allowing Peziza to subsume Plicaria, merging Plicaria-like- Peziza species with Plicaria, or assigning members of the Plicaria-like-Peziza group to a separate genus. -- Mapping of burn association character on the inferred phylogeny revealed that several monophyletic groups have evolved in association with postfire sites. All taxa that branch basally within the Plicaria/Plicaria-like-Peziza clade are postfire species. This suggests that the ancestral condition is association with burns. A similar relationship was found within the Peziza clade but only a small number of taxa were sampled from this group

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