Pollination biology of Eulophia alta (Orchidaceae) in Amazonia: effects of pollinator composition on reproductive success in different populations

Jürgens, Andreas; Bosch, Simone R.; Webber, Antonio Carlos; Witt, Taina; Frame, Dawn; Gottsberger, Gerhard

doi:10.1093/aob/mcp191

Cited by 19 publications

(17 citation statements)

References 71 publications

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“…*Citations for previously published studies: †(Peter & Johnson, ), ‡(Peter & Johnson, ), §(Peter, ), ¶(Jürgens et al ., ), **(Peter & Johnson, ), ††(Peter & Johnson, ).…”

Section: Resultsmentioning

confidence: 99%

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Generalized food deception: colour signals and efficient pollen transfer in bee-pollinated species ofEulophia(Orchidaceae)

Peter

Johnson

2013

Bot J Linn Soc

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Non‐rewarding plants use a variety of ruses to attract their pollinators. One of the least understood of these is generalized food deception, in which flowers exploit non‐specific food‐seeking responses in their pollinators. Available evidence suggests that colour signals, scent and phenology may all play key roles in this form of deception. Here we investigate the pollination systems of five Eulophia spp. (Orchidaceae) lacking floral rewards. These species are pollinated by bees, notably Xylocopa (Anthophorinae, Apidae) or Megachile (Megachilidae) for the large‐flowered species and anthophorid (Anthophorinae, Apidae) or halictid (Halictidae) bees for the small‐flowered species. Spectra of the lateral petals and ultraviolet‐absorbing patches on the labella are strongly contrasting in a bee visual system, which may falsely signal the presence of pollen to bees. All five species possess pollinarium‐bending mechanisms that are likely to limit pollinator‐mediated self‐pollination. Flowering times extend over 3–4 months and the onset of flowering was not associated with the emergence of pollinators, some of which fly year round. Despite sharing pollinators with other plants and lacking rewards that would encourage fidelity, the Eulophia spp. exhibited relatively high levels of pollen transfer efficiency compared with other rewarding and deceptive orchids. We conclude that the study species employ generalized food deception and exploit food‐seeking bees. © 2013 The Linnean Society of London,

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“…*Citations for previously published studies: †(Peter & Johnson, ), ‡(Peter & Johnson, ), §(Peter, ), ¶(Jürgens et al ., ), **(Peter & Johnson, ), ††(Peter & Johnson, ).…”

Section: Resultsmentioning

confidence: 99%

“…In addition, Jürgens et al . () and Johnson et al . () examined the breeding systems and pollination biology of Eulophia alta (L.) Fawc.…”

Section: Introductionmentioning

confidence: 86%

Generalized food deception: colour signals and efficient pollen transfer in bee-pollinated species ofEulophia(Orchidaceae)

Peter

Johnson

2013

Bot J Linn Soc

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“…They have sympodal growth with sub-terranean tubers that produce a new vegetative shoot and an inflorescence from the base of the vegetative shoot each year. All taxa of Eulophia that we have examined, including the two forms described here, are deceptive and do not reward their pollinators (Peter and Johnson, 2013), although there is evidence that two pantropical species may reward their pollinators (Singer and Cocucci, 1997;Jürgens et al, 2009).…”

Section: Study Speciesmentioning

confidence: 87%

A pollinator shift explains floral divergence in an orchid species complex in South Africa

Peter

Johnson

2013

Annals of Botany

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Aims Floral diversification driven by shifts between pollinators has been one of the key explanations for the radiation of angiosperms. According to the Grant-Stebbins model of pollinator-driven speciation, these shifts result in morphologically distinct 'ecotypes' which may eventually become recognizable as species. The current circumscription of the food-deceptive southern African orchid Eulophia parviflora encompasses a highly variable monophyletic species complex. In this study, two forms were identified within this complex that differ in distribution, floral morphology, scent chemistry and phenology, and a test was made of whether these differences represent adaptations for different pollinators. † Methods and Results Multivariate analysis of floral and vegetative traits revealed that there are at least two discrete morphological forms in the species complex. Field observations revealed that each form is pollinated by a different insect species, and thus represent distinct ecotypes. The early-flowering coastal form which has long spurs and floral scent dominated by sesquiterpene compounds is pollinated exclusively by the long-tongued bee Amegilla fallax (Apidae, Anthophorinae), while the late-flowering inland form with short spurs and floral scent dominated by benzenoid compounds is pollinated exclusively by the beetle Cyrtothyrea marginalis (Cetoniinae; Scarabaeidae). Choice experiments in a Y-maze olfactometer showed that beetles are preferentially attracted to the scent of the short-spurred form. A spur-shortening experiment showed that long spurs are required for effective pollination of the bee-pollinated form. Although it was initially thought likely that divergence occurred across a geographical pollinator gradient, plants of the long-spurred form were effectively pollinated when transplanted to an inland locality outside the natural coastal range of this form. Thus, the underlying geographical basis for the evolution of ecotypes in the E. parviflora complex remains uncertain, although early flowering in the long-spurred form to exploit the emergence of naïve bees may restrict this form to coastal areas where there is no frost that would damage flower buds. Later flowering of the short-spurred form coincides closely with the emergence of the pollinating beetles following winter frosts. † Conclusions This study identifies a shift between bee and beetle pollination as the main driver of floral divergence in an orchid species complex. Floral scent and spur length appear to be key traits in mediating this evolutionary transition.

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“…With greater availability of pollen resources in the flowering community as a whole as the season progressed, some pollinator taxa may have groomed less pollen from their bodies (Beattie 1971), resulting in greater pollen deposition. The effectiveness of some pollinators of A. tuberosa differed between years (Fishbein and Venable 1996), and within-species differences in pollinator performance have been documented among sites, suggesting that interactions with other community members are important (Jürgens et al 2009). Regardless of the underlying reasons, within-species changes in effectiveness indicate that pooling estimates of pollinator performance over temporal scales or treating them as static traits may obscure important variation and could lead to inaccurate predictions of the plant reproductive consequences of phenological shifts (Fig.…”

Section: Discussionmentioning

confidence: 99%

Pollinator effectiveness varies with experimental shifts in flowering time

Rafferty

Ives

2012

Ecology

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The earlier flowering times exhibited by many plant species are a conspicuous sign of climate change. Altered phenologies have caused concern that species could suffer population declines if they flower at times when effective pollinators are unavailable. For two perennial wildflowers, Tradescantia ohiensis and Asclepias incarnata, we used an experimental approach to explore how changing phenology affects the taxonomic composition of the pollinator assemblage and the effectiveness of individual pollinator taxa. After finding in the previous year that fruit set varied with flowering time, we manipulated flowering onset in greenhouses, placed plants in the field over the span of five weeks, and measured pollinator effectiveness as the number of seeds produced after a single visit to a flower. The average effectiveness of pollinators and the expected rates of pollination success were lower for plants of both species flowering earlier than for plants flowering at historical times, suggesting there could be reproductive costs to earlier flowering. Whereas for A. incarnata, differences in average seed set among weeks were due primarily to changes in the composition of the pollinator assemblage, the differences for T. ohiensis were driven by the combined effects of compositional changes and increases over time in the effectiveness of some pollinator taxa. Both species face the possibility of temporal mismatch between the availability of the most effective pollinators and the onset of flowering, and changes in the effectiveness of individual pollinator taxa through time may add an unexpected element to the reproductive consequences of such mismatches.

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Pollination biology of Eulophia alta (Orchidaceae) in Amazonia: effects of pollinator composition on reproductive success in different populations

Cited by 19 publications

References 71 publications

Generalized food deception: colour signals and efficient pollen transfer in bee-pollinated species ofEulophia(Orchidaceae)

Generalized food deception: colour signals and efficient pollen transfer in bee-pollinated species ofEulophia(Orchidaceae)

A pollinator shift explains floral divergence in an orchid species complex in South Africa

Pollinator effectiveness varies with experimental shifts in flowering time

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