Abstract:The pollination of one plant species can be facilitated by the presence of one or more neighboring plant species and evidence has been found in some rewardless species of orchid that benefit from the presence of rewarding plant species in the neighborhood. There are two pollination mechanisms by which a non-rewarding orchid attracts pollinators and increases its reproductive success: (1) A magnetic species effect that occurs even though the flowers do not resemble those of the other species, and (2) floral mim… Show more
“…pollinator density [16] or the magnet-species effect [7,69]), further studies need to be carried out to investigate whether there is a general pattern of increased fitness in the presence of a rewarding model. Carmona-Díaz & García-Franco [32] reported higher levels of reproductive success in the Mexican species of Trichocentrum luridum (published as Trichocentrum cosymbephorum ) when occurring in sites where Malpighia glabra (Malpighiaceae) was abundant. This phenomenon was also observed in the deceptive orchid Disa nivea in South Africa and its Scrophulariaceae nectar-producing model, Zaluzianskya microsiphon [21].…”
Section: Discussionmentioning
confidence: 99%
“…Surveys of deceitful orchids in the Mediterranean and Caribbean have concluded that this form of deception is more common than specifically mimicking a single model species [19]. Alternatively, some bee-blue-green Oncidiinae may be mimics of other malpig colour forms, as is thought to be the case between T. luridum and M. glabra [32]. …”
The great majority of plant species in the tropics require animals to achieve pollination, but the exact role of floral signals in attraction of animal pollinators is often debated. Many plants provide a floral reward to attract a guild of pollinators, and it has been proposed that floral signals of non-rewarding species may converge on those of rewarding species to exploit the relationship of the latter with their pollinators. In the orchid family (Orchidaceae), pollination is almost universally animal-mediated, but a third of species provide no floral reward, which suggests that deceptive pollination mechanisms are prevalent. Here, we examine floral colour and shape convergence in Neotropical plant communities, focusing on certain food-deceptive Oncidiinae orchids (e.g. Trichocentrum ascendens and Oncidium nebulosum) and rewarding species of Malpighiaceae. We show that the species from these two distantly related families are often more similar in floral colour and shape than expected by chance and propose that a system of multifarious floral mimicry—a form of Batesian mimicry that involves multiple models and is more complex than a simple one model–one mimic system—operates in these orchids. The same mimetic pollination system has evolved at least 14 times within the species-rich Oncidiinae throughout the Neotropics. These results help explain the extraordinary diversification of Neotropical orchids and highlight the complexity of plant–animal interactions.
“…pollinator density [16] or the magnet-species effect [7,69]), further studies need to be carried out to investigate whether there is a general pattern of increased fitness in the presence of a rewarding model. Carmona-Díaz & García-Franco [32] reported higher levels of reproductive success in the Mexican species of Trichocentrum luridum (published as Trichocentrum cosymbephorum ) when occurring in sites where Malpighia glabra (Malpighiaceae) was abundant. This phenomenon was also observed in the deceptive orchid Disa nivea in South Africa and its Scrophulariaceae nectar-producing model, Zaluzianskya microsiphon [21].…”
Section: Discussionmentioning
confidence: 99%
“…Surveys of deceitful orchids in the Mediterranean and Caribbean have concluded that this form of deception is more common than specifically mimicking a single model species [19]. Alternatively, some bee-blue-green Oncidiinae may be mimics of other malpig colour forms, as is thought to be the case between T. luridum and M. glabra [32]. …”
The great majority of plant species in the tropics require animals to achieve pollination, but the exact role of floral signals in attraction of animal pollinators is often debated. Many plants provide a floral reward to attract a guild of pollinators, and it has been proposed that floral signals of non-rewarding species may converge on those of rewarding species to exploit the relationship of the latter with their pollinators. In the orchid family (Orchidaceae), pollination is almost universally animal-mediated, but a third of species provide no floral reward, which suggests that deceptive pollination mechanisms are prevalent. Here, we examine floral colour and shape convergence in Neotropical plant communities, focusing on certain food-deceptive Oncidiinae orchids (e.g. Trichocentrum ascendens and Oncidium nebulosum) and rewarding species of Malpighiaceae. We show that the species from these two distantly related families are often more similar in floral colour and shape than expected by chance and propose that a system of multifarious floral mimicry—a form of Batesian mimicry that involves multiple models and is more complex than a simple one model–one mimic system—operates in these orchids. The same mimetic pollination system has evolved at least 14 times within the species-rich Oncidiinae throughout the Neotropics. These results help explain the extraordinary diversification of Neotropical orchids and highlight the complexity of plant–animal interactions.
“…These results are consistent with the role of Malpighiaceae as model plants for most Oncidium ‐like orchids, as has been proposed many times (Van der Pijl & Dodson 1966; Nierenberg 1971; Van der Cingel 2001; Powell et al . 2003; Pemberton 2008; Renner & Schaeffer 2010), but scarcely documented (Carmona‐Díaz & García‐Franco 2009; Pemberton 2010).…”
Section: Discussionmentioning
confidence: 99%
“…2003; Pansarin et al . 2008; Carmona‐Díaz & García‐Franco 2009). In other cases, a few species of orchids of the genus Oncidium and Tolumnia , pollinated by males of Centris bees, have been suggested to exploit the territoriality (Dodson & Frymire 1961; Van der Pijl & Dodson 1966; Nierenberg 1971) and mate‐seeking behaviors of these males bees (Dod 1976).…”
The mimicry of malpighiaceous oil-flowers appears to be a recurrent pollination strategy among many orchids of the subtribe Oncidiinae. These two plant groups are mainly pollinated by oil-gathering bees, which also specialize in pollen collection by buzzing. In the present study, the floral ecology of the rewardless orchid Tolumnia guibertiana (Oncidiinae) was studied for the first time. The orchid was self-incompatible and completely dependent on oil-gathering female bees (Centris poecila) for fruit production. This bee species was also the pollinator of two other yellow-flowered plants in the area: the pollen and oil producing Stigmaphyllon diversifolium (Malpighiaceae) and the polliniferous and buzzing-pollinated Ouratea agrophylla (Ochnaceae). To evaluate whether this system is a case of mimetism, we observed pollinator visits to flowers of the three plant species and compared the floral morphometrics of these flowers. The behavior, preferences and movement patterns of Centris bees among these plants, as well as the morphological data, suggest that, as previously thought, flowers of T. guibertiana mimic the Malpighiaceae S. diversifolium. However, orchid pollination in one of the studied populations appears to depend also on the presence of O. agrophylla. Moreover, at the two studied populations, male and female pollination successes of T. guibertiana were not affected by its own floral display, and did not differ between populations. The results are discussed in relation to the behavior and preferences of Centris bees, as well as the differential presence and influence of each of the two floral models.
“…It is generally assumed that the enlarged median sepal, incised lip, callus and stelidia of Oncidiinae evolved to mimick the shape of the petals and oil glands of rewarding flowers of Malpighiaceae (Figs. 2b–d and 3) in order to attract oil-collecting bees for pollination [35, 38, 40, 41]. Fig.…”
BackgroundThousands of flowering plant species attract pollinators without offering rewards, but the evolution of this deceit is poorly understood. Rewardless flowers of the orchid Erycina pusilla have an enlarged median sepal and incised median petal (‘lip’) to attract oil-collecting bees. These bees also forage on similar looking but rewarding Malpighiaceae flowers that have five unequally sized petals and gland-carrying sepals. The lip of E. pusilla has a ‘callus’ that, together with winged ‘stelidia’, mimics these glands. Different hypotheses exist about the evolutionary origin of the median sepal, callus and stelidia of orchid flowers.ResultsThe evolutionary origin of these organs was investigated using a combination of morphological, molecular and phylogenetic techniques to a developmental series of floral buds of E. pusilla. The vascular bundle of the median sepal indicates it is a first whorl organ but its convex epidermal cells reflect convergence of petaloid features. Expression of AGL6 EpMADS4 and APETALA3 EpMADS14 is low in the median sepal, possibly correlating with its petaloid appearance. A vascular bundle indicating second whorl derivation leads to the lip. AGL6 EpMADS5 and APETALA3 EpMADS13 are most highly expressed in lip and callus, consistent with current models for lip identity. Six vascular bundles, indicating a stamen-derived origin, lead to the callus, stelidia and stamen. AGAMOUS is not expressed in the callus, consistent with its sterilization. Out of three copies of AGAMOUS and four copies of SEPALLATA, EpMADS22 and EpMADS6 are most highly expressed in the stamen. Another copy of AGAMOUS, EpMADS20, and the single copy of SEEDSTICK, EpMADS23, are most highly expressed in the stelidia, suggesting EpMADS22 may be required for fertile stamens.ConclusionsThe median sepal, callus and stelidia of E. pusilla appear to be derived from a sepal, a stamen that gained petal identity, and stamens, respectively. Duplications, diversifying selection and changes in spatial expression of different MADS-box genes shaped these organs, enabling the rewardless flowers of E. pusilla to mimic an unrelated rewarding flower for pollinator attraction. These genetic changes are not incorporated in current models and urge for a rethinking of the evolution of deceptive flowers.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-0938-7) contains supplementary material, which is available to authorized users.
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