title: Does mycorrhizal specificity affect orchid decline and rarity?
abstract: OBJECTIVE
  Orchids rely on mycorrhizal fungi for seed germination, and many species maintain associations during later stages in their life cycle. Because of the critical dependence of orchids on fungi it has been suggested that the degree of mycorrhizal specificity may be associated with rarity and long-term survival of orchid species, especially in highly degraded or fragmented landscapes. To test this hypothesis, we compared mycorrhizal communities in two species that differed significantly in decline in Belgium and other parts of Europe. •
  
  
  METHODS
  Mycorrhizal associations were investigated in five populations of Anacamptis morio and Dactylorhiza fuchsii in Belgium. ITS-based DNA arrays were used for simultaneous detection and identification of a wide range of basidiomycetous mycorrhizal fungi. Mycorrhizal specificity, measured as phylogenetic diversity, was assessed for each population and compared between species. •
  
  
  RESULTS
  For both species, the degree of phylogenetic relatedness of the mycorrhizal partners was low, and both species were associated with a large number of fungal lineages related to clades of the Tulasnellaceae family. Contrary to expectations, the species that was apparently resilient to decline was associated with fewer fungal operational taxonomical units than the declining species was, and the phylogenetic relatedness of mycorrhizal communities among populations was higher in the stable than in the declining orchid. •
  
  
  CONCLUSIONS
  Although our results do not present detailed insights into the causes of orchid persistence, they do suggest that orchid rarity and persistence are not necessarily related to fungal diversity and that other factors may be more important in determining orchid persistence.
authors.affiliation: Division of Plant Ecology and Systematics, Biology Department, KU Leuven, Kasteelpark Arenberg 31, B-3001 Heverlee, Belgium. bruno.cachapabailarote@bio.kuleuven.be
authors.forename: Bruno Cachapa
authors.initials: BC
authors.lastname: Bailarote
authors.forename: Bart
authors.initials: B
authors.lastname: Lievens
authors.forename: Hans
authors.initials: H
authors.lastname: Jacquemyn
mesh_terms: D001499:Bayes Theorem; D021901:DNA, Intergenic / Q000235:genetics; D056727:Endangered Species; D038821:Mycorrhizae / Q000235:genetics / Q000502:physiology*; D029595:Orchidaceae / Q000382:microbiology*; D010802:Phylogeny; D013045:Species Specificity
chemical_list: D021901:DNA, Intergenic