title: Apomixis and reticulate evolution in the Asplenium monanthes fern complex.
abstract: OBJECTIVE
  Asexual reproduction is a prominent evolutionary process within land plant lineages and especially in ferns. Up to 10 % of the approx. 10 000 fern species are assumed to be obligate asexuals. In the Asplenium monanthes species complex, previous studies identified two triploid, apomictic species. The purpose of this study was to elucidate the phylogenetic relationships in the A. monanthes complex and to investigate the occurrence and evolution of apomixis within this group.
  
  
  METHODS
  DNA sequences of three plastid markers and one nuclear single copy gene were used for phylogenetic analyses. Reproductive modes were assessed by examining gametophytic and sporophyte development, while polyploidy was inferred from spore measurements.
  
  
  RESULTS
  Asplenium monanthes and A. resiliens are confirmed to be apomictic. Asplenium palmeri, A. hallbergii and specimens that are morphologically similar to A. heterochroum are also found to be apomictic. Apomixis is confined to two main clades of taxa related to A. monanthes and A. resiliens, respectively, and is associated with reticulate evolution. Two apomictic A. monanthes lineages, and two putative diploid sexual progenitor species are identified in the A. monanthes clade.
  
  
  CONCLUSIONS
  Multiple origins of apomixis are inferred, in both alloploid and autoploid forms, within the A. resiliens and A. monanthes clades.
authors.affiliation: Department of Botany, Natural History Museum, London, UK. r.dyer@nhm.ac.uk
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Dyer
authors.forename: Vincent
authors.initials: V
authors.lastname: Savolainen
authors.forename: Harald
authors.initials: H
authors.lastname: Schneider
mesh_terms: D060832:Apomixis / Q000235:genetics*; D001483:Base Sequence; D001499:Bayes Theorem; D005075:Biological Evolution; D002467:Cell Nucleus / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics / Q000302:isolation & purification; D029624:Ferns / Q000145:classification / Q000235:genetics* / Q000502:physiology; D005819:Genetic Markers / Q000235:genetics; D008954:Models, Biological; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics; D018087:Plastids / Q000235:genetics; D011003:Ploidies; D011123:Polyploidy; D012100:Reproduction, Asexual / Q000235:genetics; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D018744:DNA, Plant; D005819:Genetic Markers; D010940:Plant Proteins