Phenotypical plasticity and homoplasy complicate species delimitation in the Cladonia gracilis group (Cladoniaceae, Asco
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ORIGINAL ARTICLE
Phenotypical plasticity and homoplasy complicate species delimitation in the Cladonia gracilis group (Cladoniaceae, Ascomycota) Raquel Pino-Bodas & Ana Rosa Burgaz & María P. Martín & H. Thorsten Lumbsch
Received: 21 March 2011 / Accepted: 2 October 2011 / Published online: 20 October 2011 # Gesellschaft für Biologische Systematik 2011
Abstract Species delimitation in the Cladonia gracilis group has long been known to be difficult due to morphological variability of taxa. The present study addresses the circumscription of species within this group, examining a number of specimens of the currently accepted taxa Cladonia coniocraea, C. cornuta subsp. cornuta, C. cornuta subsp. groenlandica, C. ecmocyna subsp. ecmocyna, C. ecmocyna subsp. intermedia, C. gracilis subsp. gracilis, C. gracilis subsp. elongata, C. gracilis subsp. tenerrima, C. gracilis subsp. turbinata, C. gracilis subsp. vulnerata, C. macroceras, C. maxima, and C. ochrochlora using genealogical concordance phylogenetic species recognition. We employed maximum parsimony, maximum likelihood and Bayesian methods of phylogenetic reconstructions based on DNA sequences of ITS rDNA, IGS rDNA, RPB2 and partially EF1-α regions. Our results indicate that the C. gracilis group is monophyletic but that most currently accepted taxa do not form monophyletic groups, with the exception of C. ecmocyna and C. cornuta subsp. cornuta. Different tests suggest that incomplete lineage sorting and sporadic recombination events are responsible for a phylogeny that largely R. Pino-Bodas (*) : A. R. Burgaz Departamento de Biología Vegetal 1, Facultad de Biología, Universidad Complutense de Madrid, 28040 Madrid, Spain e-mail: [email protected] M. P. Martín Departamento de Micología, Real Jardín Botánico, CSIC, 28014 Madrid, Spain H. T. Lumbsch Department of Botany, The Field Museum, 1400 S. Lake Shore Drive, Chicago, IL 60605, USA
lacks support. Our data also strongly suggest that C. coniocraea, C. cornuta subsp. groenlandica, and C. ochrochlora are conspecific, with C. coniocraea being the oldest available name. The morphological characters in the group are shown to be highly homoplasious, causing, in tandem with phenotypical plasticity of the taxa, the difficulties in delimiting species in the C. gracilis group. Keywords Genealogical concordance phylogenetic species recognition . Lichens . Morphology . Taxonomy . Variability
Introduction Understanding morphological variation in the different groups of organisms is a key to identify diagnostic characters allowing for taxon delimitation. Nevertheless, this task is hindered by phenotypical plasticity, i.e., the ability of a genotype to express different phenotypes as a response to environmental conditions. This fact is widely known for many groups of organisms (Sultan 1987; Lortie and Aarssen 1996; Trussell 1996; Schichting 2002; Whitman and Ananthakrishnan 2008; Hollander and Butlin 2010), including lichenized fungi (Nash et al. 1990; Pintado et al. 1997; Rikkinen 1997). In order to assess the phenotypical plasti
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