title: Phylogeographic patterns, genetic affinities and morphological differentiation between Epipactis helleborine and related lineages in a Mediterranean glacial refugium.
abstract: OBJECTIVE
  In the Mediterranean basin, the Italian peninsula has been suggested to be one of the most important glacial refugia for temperate tree species. The orchid genus Epipactis is widely represented in the Italian peninsula by widespread species and several endemic, localized taxa, including selfing and outcrossing taxa. Here the phylogenetic and phylogeographic relationships in a group of closely related taxa in Epipactis are investigated with the aim of understanding the role of this refugial area for cladogenesis and speciation in herbaceous species, such as terrestrial orchids.
  
  
  METHODS
  Ribosomal DNA (rDNA) was employed to assess phylogenetic relationships, and plastid sequence variation in the rbcL-accD spacer was used to reveal phylogeographic patterns among plastid haplotypes using a parsimony network.
  
  
  RESULTS
  Low genetic variation and shared ribotypes were detected in rDNA, whereas high levels of sequence variation and a strong phylogeographic structure were found in the examined plastid region. The parsimony plastid haplotype network identified two main haplotype groups, one including E. atrorubens/microphylla/muelleri/leptochila and the other including all accessions of E. helleborine and several localized and endemic taxa, with a combination of widespread and rare haplotypes detected across the Italian peninsula. A greater genetic divergence separated the Italian and other European accessions of E. helleborine.
  
  
  CONCLUSIONS
  Phylogenetic and phylogeographic patterns support a working hypothesis in which the Italian peninsula has only recently been colonized by Epipactis, probably during the most recent phase of the Quaternary age and, nevertheless, it acted as a remarkable centre of diversification for this orchid lineage. Changes in pollination strategy and recurrent shifts in mating system (from allogamy to autogamy) could have represented the mechanism promoting this rapid diversification and the observed high taxonomic complexity detected in the E. helleborine species complex.
authors.affiliation: Sezione di Biologia ed Ecologia Vegetale DACPA, Università di Catania, via Vadisavoia 5, Catania, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Tranchida-Lombardo
authors.forename: Donata
authors.initials: D
authors.lastname: Cafasso
authors.forename: Antonia
authors.initials: A
authors.lastname: Cristaudo
authors.forename: Salvatore
authors.initials: S
authors.lastname: Cozzolino
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000235:genetics; D000595:Amino Acid Sequence; D018742:DNA, Chloroplast / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D004777:Environment; D019143:Evolution, Molecular; D049810:Genetic Speciation; D014644:Genetic Variation; D006239:Haplotypes / Q000235:genetics; D007558:Italy; D008969:Molecular Sequence Data; D029595:Orchidaceae / Q000033:anatomy & histology / Q000201:enzymology / Q000235:genetics*; D010802:Phylogeny; D058974:Phylogeography; D010940:Plant Proteins / Q000235:genetics; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D018742:DNA, Chloroplast; D004275:DNA, Ribosomal; D010940:Plant Proteins; C101625:RbcL protein, plastid; D012273:Ribulose-Bisphosphate Carboxylase; D000103:Acetyl-CoA Carboxylase