Evolutionary relationships among pollinators and repeated pollinator sharing in sexually deceptive orchids

R. D. Phillips, G. R. Brown, K. W. Dixon, C. Hayes, C. C. Linde, R. Peakall

    Research output: Contribution to journalArticle

    9 Citations (Scopus)

    Abstract

    The mechanism of pollinator attraction is predicted to strongly influence both plant diversification and the extent of pollinator sharing between species. Sexually deceptive orchids rely on mimicry of species-specific sex pheromones to attract their insect pollinators. Given that sex pheromones tend to be conserved among related species, we predicted that in sexually deceptive orchids, (i) pollinator sharing is rare, (ii) closely related orchids use closely related pollinators and (iii) there is strong bias in the wasp lineages exploited by orchids. We focused on species that are pollinated by sexual deception of thynnine wasps in the distantly related genera Caladenia and Drakaea, including new field observations for 45 species of Caladenia. Specialization was extreme with most orchids using a single pollinator species. Unexpectedly, seven cases of pollinator sharing were found, including two between Caladenia and Drakaea, which exhibit strikingly different floral morphology. Phylogenetic analysis of pollinators using four nuclear sequence loci demonstrated that although orchids within major clades primarily use closely related pollinator species, up to 17% of orchids within these clades are pollinated by a member of a phylogenetically distant wasp genus. Further, compared to the total diversity of thynnine wasps within the study region, orchids show a strong bias towards exploiting certain genera. Although these patterns may arise through conservatism in the chemical classes used in sex pheromones, apparent switches between wasp clades suggest unexpected flexibility in floral semiochemical production. Alternatively, wasp sex pheromones within lineages may exhibit greater chemical diversity than currently appreciated.

    Original languageEnglish
    Pages (from-to)1674-1691
    Number of pages18
    JournalJournal of Evolutionary Biology
    Volume30
    Issue number9
    DOIs
    Publication statusPublished - Sep 2017

    Cite this

    Phillips, R. D. ; Brown, G. R. ; Dixon, K. W. ; Hayes, C. ; Linde, C. C. ; Peakall, R. / Evolutionary relationships among pollinators and repeated pollinator sharing in sexually deceptive orchids. In: Journal of Evolutionary Biology. 2017 ; Vol. 30, No. 9. pp. 1674-1691.
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    abstract = "The mechanism of pollinator attraction is predicted to strongly influence both plant diversification and the extent of pollinator sharing between species. Sexually deceptive orchids rely on mimicry of species-specific sex pheromones to attract their insect pollinators. Given that sex pheromones tend to be conserved among related species, we predicted that in sexually deceptive orchids, (i) pollinator sharing is rare, (ii) closely related orchids use closely related pollinators and (iii) there is strong bias in the wasp lineages exploited by orchids. We focused on species that are pollinated by sexual deception of thynnine wasps in the distantly related genera Caladenia and Drakaea, including new field observations for 45 species of Caladenia. Specialization was extreme with most orchids using a single pollinator species. Unexpectedly, seven cases of pollinator sharing were found, including two between Caladenia and Drakaea, which exhibit strikingly different floral morphology. Phylogenetic analysis of pollinators using four nuclear sequence loci demonstrated that although orchids within major clades primarily use closely related pollinator species, up to 17{\%} of orchids within these clades are pollinated by a member of a phylogenetically distant wasp genus. Further, compared to the total diversity of thynnine wasps within the study region, orchids show a strong bias towards exploiting certain genera. Although these patterns may arise through conservatism in the chemical classes used in sex pheromones, apparent switches between wasp clades suggest unexpected flexibility in floral semiochemical production. Alternatively, wasp sex pheromones within lineages may exhibit greater chemical diversity than currently appreciated.",
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    Evolutionary relationships among pollinators and repeated pollinator sharing in sexually deceptive orchids. / Phillips, R. D.; Brown, G. R.; Dixon, K. W.; Hayes, C.; Linde, C. C.; Peakall, R.

    In: Journal of Evolutionary Biology, Vol. 30, No. 9, 09.2017, p. 1674-1691.

    Research output: Contribution to journalArticle

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    AU - Phillips, R. D.

    AU - Brown, G. R.

    AU - Dixon, K. W.

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    AB - The mechanism of pollinator attraction is predicted to strongly influence both plant diversification and the extent of pollinator sharing between species. Sexually deceptive orchids rely on mimicry of species-specific sex pheromones to attract their insect pollinators. Given that sex pheromones tend to be conserved among related species, we predicted that in sexually deceptive orchids, (i) pollinator sharing is rare, (ii) closely related orchids use closely related pollinators and (iii) there is strong bias in the wasp lineages exploited by orchids. We focused on species that are pollinated by sexual deception of thynnine wasps in the distantly related genera Caladenia and Drakaea, including new field observations for 45 species of Caladenia. Specialization was extreme with most orchids using a single pollinator species. Unexpectedly, seven cases of pollinator sharing were found, including two between Caladenia and Drakaea, which exhibit strikingly different floral morphology. Phylogenetic analysis of pollinators using four nuclear sequence loci demonstrated that although orchids within major clades primarily use closely related pollinator species, up to 17% of orchids within these clades are pollinated by a member of a phylogenetically distant wasp genus. Further, compared to the total diversity of thynnine wasps within the study region, orchids show a strong bias towards exploiting certain genera. Although these patterns may arise through conservatism in the chemical classes used in sex pheromones, apparent switches between wasp clades suggest unexpected flexibility in floral semiochemical production. Alternatively, wasp sex pheromones within lineages may exhibit greater chemical diversity than currently appreciated.

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    KW - THYNNINE WASPS HYMENOPTERA

    KW - CALADENIA ORCHIDACEAE

    KW - SPECIALIZED POLLINATION

    KW - REPRODUCTIVE ISOLATION

    KW - DRIVEN SPECIATION

    KW - BEES HYMENOPTERA

    KW - CHEMICAL ECOLOGY

    KW - FLORAL ISOLATION

    KW - SOUTHERN AFRICA

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