Scent variation and hybridization cause the displacement of a sexually deceptive orchid species

Stökl, Johannes; Schlüter, Philipp M.; Stuessy, Tod F.; Paulus, Hannes F.; Assum, Günter; Ayasse, Manfred

doi:10.3732/ajb.95.4.472

Cited by 69 publications

(78 citation statements)

References 31 publications

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“…Here, postmating isolation is highly limited and the species boundary is mainly maintained by premating isolation due to specificity of pollinator attraction. However, when hybridizing, due to absence of other late postmating barriers that halt interspecific gene flow, sexually deceptive hybrid zones are formed by hybrids of different genetic categories and large introgression occurs among parental species (Stökl et al, 2008). Under this scenario, the hybrid zone may produce a wide genetic merging of parental species.…”

Section: Pollination Specificity Hybridization and Hybrid Conservationmentioning

confidence: 99%

Pollination Syndromes in Mediterranean Orchids—Implications for Speciation, Taxonomy and Conservation

2010

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The Mediterranean flora is spectacularly rich in orchid species that have evolved remarkable adaptations to their environment. Orchids have complex and delicate interactions with their pollinators, which makes them particularly prone to local extinction. Conservation actions should be encouraged for a range of endangered Mediterranean orchid species, but the current taxonomic confusion in several genera and the apparent disagreement among orchid taxonomists make the situation particularly confusing from a conservation perspective. In this review, we document how the different pollination syndromes of Mediterranean orchids (nectar reward, shelter offering, food deception and sexual deception) can have a profound impact on the type of reproductive barriers among species, on floral phenotypic variation as we perceive it, on potentially related processes of species sorting and extinction and, consequently, should have a strong influence on the related conservation management programs. We also highlight that the majority of Mediterranean orchids are pollinated by specialised bees often occupying otherwise narrow ecological niches (e.g. pollen specialisation, brood cell parasites, specific nesting site). This condition makes the orchid-pollinator interactions very fragile and several orchid species prone to local extinction. We illustrate this phenomenon by a selection of case studies that show how the adequate integration of the ecological requirements/traits of the orchids and their associated pollinators into conservation actions could help protect endangered species and ensure the sustainability of the often complex local pollination web.

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Section: Pollination Specificity Hybridization and Hybrid Conservationmentioning

confidence: 99%

Pollination Syndromes in Mediterranean Orchids—Implications for Speciation, Taxonomy and Conservation

2010

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“…By contrast, in sexually deceptive orchids for which few loci contribute to isolation, more extensive gene exchange occurs in hybrid zones. Several sexually deceptive Ophrys species can be distinguished by scent emission, but they are genetically differentiated only weakly and their genomes largely introgress when hybridizing (Stökl et al 2008). Thus, in sexually deceptive species, only small portions of the genome may be sheltered from introgression.…”

Section: Genetic Bases Of Reproductive Isolation and Species Differenmentioning

confidence: 99%

Specificity in pollination and consequences for postmating reproductive isolation in deceptive Mediterranean orchids

Cozzolino

Scopece

2008

Phil. Trans. R. Soc. B

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The type of reproductive isolation prevalent in the initial stages of species divergence can affect the nature and rate of emergence of additional reproductive barriers that subsequently strengthen isolation between species. Different groups of Mediterranean deceptive orchids are characterized by different levels of pollinator specificity. Whereas food-deceptive orchid species show weak pollinator specificity, the sexually deceptive Ophrys species display a more specialized pollination strategy. Comparative analyses reveal that orchids with high pollinator specificity mostly rely on premating reproductive barriers and have very little postmating isolation. In this group, a shift to a novel pollinator achieved by modifying the odour bouquet may represent the main isolation mechanism involved in speciation. By contrast, orchids with weak premating isolation, such as generalized fooddeceptive orchids, show strong evidence for intrinsic postmating reproductive barriers, particularly for late-acting postzygotic barriers such as hybrid sterility. In such species, chromosomal differences may have played a key role in species isolation, although strong postmating-prezygotic isolation has also evolved in these orchids. Molecular analyses of hybrid zones indicate that the types and strength of reproductive barriers in deceptive orchids with contrasting premating isolation mechanisms directly affect the rate and evolutionary consequences of hybridization and the nature of species differentiation.

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“…Other potential pre-zygotic isolation mechanisms are also absent including differences in pollen position on the vector and flowering times. Hybrids are considered to be relatively common in Caladenia (Backhouse and Jeanes 1995) suggesting that postzygotic reproductive barriers to hybridisation in the genus are weak or absent, which is also characteristic of sexual deception in general (Peakall et al 1997, Stökl et al 2008, Vereecken et al 2010, Xu et al 2011, Whitehead and Peakall 2104. The distribution of C. villosissima overlaps extensively with that of C. parva in western Victoria, and the distributions of C. phaeoclavia and C. parva meet in southern Victoria and the Grampians, indicating there is a high likelihood of introgression between the three taxa.…”

Section: Discussionmentioning

confidence: 99%

Pollinator sharing by the sexually deceptive Green-comb Spider Orchids, Caladenia phaeoclavia, C. parva and C. villosissima (Orchidaceae: Caladeniinae): taxonomic considerations

Bower¹

2015

Telopea

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Sexually deceptive orchids are pollinated when male insects perform mating behaviours on the femalemimicking labellum. Such orchids are characterised by extreme pollinator specificity, having only one, or occasionally a few, closely related insect species as pollen vectors. Sharing of a sexually deceived pollinator species between two or more orchid species is rare among Australian orchids in the Drakaeinae and Caladeniinae pollinated by male Thynnid wasps. In this paper putative pollinator sharing within a complex of three morphologically similar species of Greencomb Spider Orchids, Caladenia parva G.W. Carr, C. phaeoclavia D.L. Jones and C. villosissima G.W. Carr, was investigated using pollinator baiting and choice testing in the field. The three orchid taxa are shown to share the same thynnid wasp pollen vector, Lophocheilus anilitatus (Smith) over the entire geographic range of the complex in New South Wales and Victoria. Pollinator baiting and choice testing at 42 locations revealed no evidence for the existence of cryptic pollinator species in L. anilitatus. The close morphological similarity of the three orchids, their sharing of the same pollinator and lack of evidence of a reproductive isolating mechanism, suggest they belong to the same biological species, C. parva. However, phylogenetic analysis is desirable to confirm the monophyly of the three morphospecies and the possible existence of polyploidy in C. villosissima merits investigation.

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Scent variation and hybridization cause the displacement of a sexually deceptive orchid species

Cited by 69 publications

References 31 publications

Pollination Syndromes in Mediterranean Orchids—Implications for Speciation, Taxonomy and Conservation

Pollination Syndromes in Mediterranean Orchids—Implications for Speciation, Taxonomy and Conservation

Specificity in pollination and consequences for postmating reproductive isolation in deceptive Mediterranean orchids

Pollinator sharing by the sexually deceptive Green-comb Spider Orchids, Caladenia phaeoclavia, C. parva and C. villosissima (Orchidaceae: Caladeniinae): taxonomic considerations

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