Systematics Section / ASPT
Bateman, Richard M , Devey, Dion , Fay, Michael F. , Hawkins, Julie A. , Malmgren, Svante , Rudall, Paula, J. .
Conflicting species concepts in the controversial insect-mimicking Mediterranean orchid genus Ophrys.
RADICALLY conflicting estimates of the number of species encompassed by a single genus often reflect paucity of taxonomic knowledge. However, two centuries of intensive study of the European terrestrial orchid genus Ophrys have led to monographic studies that recognize few (16 species plus 34 subspecies in Sundermann 1980; 19 species plus 46 subspecies in Faurholdt & Pedersen in press) or many species (150 species forming 29 complexes in Devillers & Devillers-Terschuren 1994; 215 species forming 30 complexes in Delforge 2001), understandably nonplussing conservation bodies. Unlike many problematic groups, Ophrys species are both diploid and outcrossing. The striking yet largely continuous variation in floral morphology of the flowers may have tempted some systematists into partitioning variation unusually finely. However, the main driver encouraging recognition of new species (currently circa 10 new species annually) is the assumption that each subtly distinct morphological variant in each geographically definable region has its own specific pollinating insect; a consequence of the pseudocopulatory pollination mechanism that explains the three-dimensionality, heterogeneous colours and textures, and complex pseudo-pheromones of its remarkable labellum. Our thoroughly sampled molecular phylogeny resolves only ten groups within the genus, five of which contain only one widespread species. The five remaining clusters of molecularly near-identical DNAs together encompass most of Delforge’s 215 species. Although low sequence divergence would be expected in a recent phenotypic radiation, the maintenance within many individuals of multiple plastid haplotypes and multiple ITS alleles suggests much recent introgression among these supposed species. Together with breeding experiments that recover multiple “species” from a single selfed flower, this refutes the species concept based on the hypothesis of one pollinator per trivial variant. Frequent phenotypic convergence is evident, especially between the western and eastern Mediterranean. Given this evidence, we view most of the described phenotypes as either infraspecific taxa or hybrid swarms.
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1 - Natural History Museum, Department of Botany, Cromwell Road, London, SW7 5BD, England
2 - Royal Botanic Gardens, Kew, Jodrell Laboratory, Richmond, Surrey, TW9 3AB, United Kingdom
3 - University of Reading, School of Plant Sciences, Whiteknights, Reading, RG6 6AS, United Kingdom
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, August 2nd, 2006
Time: 10:15 AM