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Taxonomic complexity, conservation and recurrent origins of self-pollination in Epipactis (Orchidaceae) / Peter M. Hollingsworth

Public in Current taxonomic research on the British & European Flora (Leicester, 13-14 September 2003) / John Bailey (2006) Titre : Taxonomic complexity, conservation and recurrent origins of self-pollination in Epipactis (Orchidaceae) Type de document : texte imprimé Auteurs : Peter M. Hollingsworth, Auteur ; J. Squirrell, Auteur ; M.L. Hollingsworth, Auteur ; A. J. Richards, Auteur ; Richard M. Bateman, Auteur Importance : pp. 27-44 Langues : Anglais (eng) Catégories : [Espèces (in biblio)] Epipactis [Thèmes] Taxonomie Mots-clés : cpSSRs  plante endémique  marqueur génétique  RFLPs Résumé : "The recent post-glacial colonisation of Britain has given little time for the evolution of endemic plant species. The few British endemic species that have been recognised tend to occur in taxonomically complex groups that possess mechanisms promoting rapid diversi-fication. Such taxonomie complexity leads to problems for plant conservation because a species has to be circumscribed and recognised before its distribution, status and threats can be established. One classic example of the challenges for conservation in taxonomie ally complex groups is the British endemic orchid Epipactis youngiana. This species is afforded full legal conservation protection but is one of a large number of taxonomically difficult species recently recognised in the genus; it is difficult to distinguish from the more common E. helleborine, and its species status has been questioned. We have used a combination of genetic markers (allozymes, chloroplast microsatellites and RFLPs) from a large sample set to establish the taxonomie and conservation status of E. youngiana and to place it in the wider context of patterns of breeding system variation and taxon differentiation in the genus. Our data provide evidence that recurrent breeding system transitions between cross-pollination and self-pollination are an important mechanism for diversification in the genus, and there are numerous genetically different taxa that are homozygous and uniform for different subsets of allelic diversity found in allogamous species. E. youngiana is the one major exception to this pattern. It has a floral morphology consistent with self-pollination, but has not achieved reproductive isolation from E. helleborine. The potential mechanisms underlying the recurrent evolution of self-pollination in Epipactis are discussed, as is the need for developing conservation strategies that reflect dynamic diversification in the genus, rather than the current heavily typological (is it distinct or not?) species-based approach." (source : auteurs) Type de publication : article de livre Référence biblio : Hollingsworth P.-M., Squirrell J., Hollingsworth M.-L., Richards A.-J., Bateman R., 2006 - Taxonomic complexity, conservation and recurrent origins of self-pollination in Epipactis (Orchidaceae). In : Bailey J., Ellis G., Eds, 2006 - Current taxonomic research on the British & European Flora (Leicester, 13-14 September 2003). London : Botanical Society of the British Isles, 27-44. ID PMB : 6459 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=6459

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