title: Is the extremely rare Iberian endemic plant species Castrilanthemum debeauxii (Compositae, Anthemideae) a 'living fossil'? Evidence from a multi-locus species tree reconstruction.
abstract: The present study provides results of multi-species coalescent species tree analyses of DNA sequences sampled from multiple nuclear and plastid regions to infer the phylogenetic relationships among the members of the subtribe Leucanthemopsidinae (Compositae, Anthemideae), to which besides the annual Castrilanthemum debeauxii (Degen, Hervier & É.Rev.) Vogt & Oberp., one of the rarest flowering plant species of the Iberian Peninsula, two other unispecific genera (Hymenostemma, Prolongoa), and the polyploidy complex of the genus Leucanthemopsis belong. Based on sequence information from two single- to low-copy nuclear regions (C16, D35, characterised by Chapman et al. (2007)), the multi-copy region of the nrDNA internal transcribed spacer regions ITS1 and ITS2, and two intergenic spacer regions of the cpDNA gene trees were reconstructed using Bayesian inference methods. For the reconstruction of a multi-locus species tree we applied three different methods: (a) analysis of concatenated sequences using Bayesian inference (MrBayes), (b) a tree reconciliation approach by minimizing the number of deep coalescences (PhyloNet), and (c) a coalescent-based species-tree method in a Bayesian framework ((∗)BEAST). All three species tree reconstruction methods unequivocally support the close relationship of the subtribe with the hitherto unclassified genus Phalacrocarpum, the sister-group relationship of Castrilanthemum with the three remaining genera of the subtribe, and the further sister-group relationship of the clade of Hymenostemma+Prolongoa with a monophyletic genus Leucanthemopsis. Dating of the (∗)BEAST phylogeny supports the long-lasting (Early Miocene, 15-22Ma) taxonomical independence and the switch from the plesiomorphic perennial to the apomorphic annual life-form assumed for the Castrilanthemum lineage that may have occurred not earlier than in the Pliocene (3Ma) when the establishment of a Mediterranean climate with summer droughts triggered evolution towards annuality.
authors.affiliation: Plant Evolution Group, Institute of Plant Sciences, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Tomasello
authors.affiliation: Real Jardín Botánico, Consejo Superior de Investigaciones Científicas, Pza. de Murillo 2, E-28104 Madrid, Spain.
authors.forename: Inés
authors.initials: I
authors.lastname: Álvarez
authors.affiliation: Real Jardín Botánico, Consejo Superior de Investigaciones Científicas, Pza. de Murillo 2, E-28104 Madrid, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Vargas
authors.affiliation: Plant Evolution Group, Institute of Plant Sciences, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany. Electronic address: christoph.oberprieler@biologie.uni-regensburg.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Oberprieler
mesh_terms: D019659:Asteraceae / Q000145:classification* / Q000235:genetics; D001499:Bayes Theorem; D018742:DNA, Chloroplast / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D005060:Europe; D005580:Fossils; D008957:Models, Genetic; D010802:Phylogeny; D011123:Polyploidy; D017422:Sequence Analysis, DNA
chemical_list: D018742:DNA, Chloroplast; D018744:DNA, Plant; D021903:DNA, Ribosomal Spacer
keywords: Chronogram; Coalescent; Gene tree; Incomplete lineage sorting; Leucanthemopsidinae; Species tree