Bee-Mediated Selection Favors Floral Sex Specialization in a Heterantherous Species: Strategies to Solve the Pollen Dilemma

Oliveira, Larissa Chagas de; Teixido, Alberto L.; Trevizan, Renata; Brito, Vinícius Lourenço Garcia de

doi:10.3390/plants9121685

Cited by 7 publications

(3 citation statements)

References 78 publications

(101 reference statements)

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“…Given that buzz‐pollinated flowers reward pollinators with pollen, the male reproductive agent, stronger selection is expected on male (“pollen dilemma”) than female function (Oliveira et al, 2020). This expectation is met by our finding that male pollination performance, but not female, was affected more strongly by floral shape variation.…”

Section: Discussionmentioning

confidence: 99%

Using geometric morphometrics to determine the “fittest” floral shape: A case study in large‐flowered, buzz‐pollinated Meriania hernandoi

Dellinger,

Hanusch,

Oswald

et al. 2023

American J of Botany

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Premise: Floral shape (relative arrangement and position of floral organs) is critical in mediating fit with pollinators and maximizing conspecific pollen transfer particularly in functionally specialized systems. To date, however, few studies have attempted to quantify flowers as the inherently three-dimensional (3D) structures they are and determine the effect of intraspecific shape variation on pollen transfer. We here addressed this research gap using a functionally specialized system, buzz pollination, in which bees extract pollen through vibrations, as a model. Our study species, Meriania hernandoi (Melastomataceae), undergoes a floral shape change from pseudocampanulate corollas with more actinomorphically arranged stamens (first day) to open corollas with a more zygomorphic androecium (second day) over anthesis, providing a natural experiment to test how variation in floral shape affects pollination performance. Methods: In one population of M. hernandoi, we bagged 51 pre-anthetic flowers and exposed half of them to bee pollinators when they were in either stage of their shape transition. We then collected flowers, obtained 3D flower models through x-ray computed tomography for 3D geometric morphometric analyses, and counted the pollen grains remaining per stamen (male pollination performance) and stigmatic pollen loads (female pollination performance). Results: Male pollination performance was significantly higher in open flowers with zygomorphic androecia than in pseudo-campanulate flowers. Female pollination performance did not differ among floral shapes. Conclusions: These results suggest that there is an "optimal" shape for male pollination performance, while the movement of bees around the flower when buzzing the spread-out stamens results in sufficient pollen deposition regardless of floral shape.

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Section: Discussionmentioning

confidence: 99%

Using geometric morphometrics to determine the “fittest” floral shape: A case study in large‐flowered, buzz‐pollinated Meriania hernandoi

Dellinger,

Hanusch,

Oswald

et al. 2023

American J of Botany

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“…The androecia of many species of Melastomataceae have dimorphic anthers, a feature that may enhance attractiveness to bees and facilitate their grasping of the anthers (Renner, 1989). Intermediate levels of heteranthery and stylar dimporphism resulted from bee-mediated selection in Macairea radula (Melastomataceae) (Oliveira et al, 2020). Stamen dimorphism is more likely to evolve when pollinators can discriminate between morphs offering different rewards, as described by Dellinger, Artuso, et al (2021) for bird visitation of Melastomaceae, which allows for staggered pollen release in some species.…”

Section: Stamens and Staminodesmentioning

confidence: 99%

Dillenia (Dilleniaceae) pollen heteromorphy and presentation, and implications for pollination by bats

Petit,

Scanlon,

Naikatini

et al. 2024

Ecology and Evolution

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Bat pollination of Dillenia in Fiji, a genus that was presumed to be pollinated by bees, posits that other Dillenia species may be bat‐pollinated, with implications for conservation and the understanding of angiosperm evolution. Botanical descriptions of some corolla behaviours (‘falling as a whole’) suggest bat removal of permanently closed corollas, as in D. biflora. Considering the remoteness of species of interest, we reviewed some Dillenia floral traits to hypothesise what they may mean for bat pollination of the genus. We investigated D. biflora pollen grains apertures and reviewed Dillenia literature concerning corolla behaviour and colour, and pollen apertures and presentation, including pores and staminodes. Our samples had dramatically different ratios of tricolpate to tetracolpate pollen grains, a trait that does not exclude pollination by bees. Petal colour polymorphism occurs, with mixed colours proportionately less common in flowers with corollas that open. The proportion of species with staminodes did not differ between those presumed to be pollinated by bats and others, but anthers of the former were significantly more likely to have apical pores, and stamens all had similar length or were slightly longer in the middle, whereas stamens in two distinct groups occurred in 55% of bee‐pollinated species. Pollen heteromorphy may facilitate pollination by different taxa in tropical environments. However, anther apical pores and stamen uniformity are more likely to be associated with bat‐pollinated species than are other morphologies. Dillenia could be a useful model to examine evolutionary aspects of colour, heteranthery, staminodes and pollen heteromorphy. Only field work will verify bat pollination and the implications of bat dependence for Dillenia species.

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“…S1) and then photographed. During photo shoots, the lens was arranged parallel to the plane of the glass plate and its focal length was adjusted to 50 mm to avoid parallax effects as much as possible (Oliveira et al 2020). Before the collection of digital landmarks and semi-landmarks, the photographs were organized using the TpsUtil software (http://life.bio.sunysb.edu/ morph/).…”

Section: Shape and Size Of Floral Structuresmentioning

confidence: 99%

Flower morphology and plant–bee pollinator interactions are related to stamen dimorphism in Melastomataceae

et al. 2021

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Approximately 20,000 species of flowering plant offer mainly pollen to their pollinators, generally bees. Stamen dimorphism, a floral trait commonly present in some pollen flowers, is thought to be associated with exclusive pollen provision for highly effective bee pollinators. Notwithstanding, little is known about how stamen dimorphism is related to other floral morphological traits and, consequently, plant-pollinator interactions at the community scale. Here we investigated the relationship between stamen dimorphism and other floral morphological traits, as well as the interactions with pollinators in plants of Melastomataceae.• We characterized each plant species as stamen dimorphic or stamen isomorphic according to differences in size and shape between stamen sets. Data on interactions between the plants and their bee pollinators were analysed as quantitative bipartite networks.• We found that petal and style size and shape were correlated to stamen dimorphism.Stamen dimorphic species present larger flowers and less variable style shapes than stamen isomorphic species. Furthermore, stamen dimorphism is associated with higher richness of visiting bees, i.e. higher ecological generalization.• During the evolutionary history of Melastomataceae, the dependence on pollinators for fruit set has possibly favoured the evolution of larger flowers with dimorphic stamens, which in turn are able to make use of a larger spectrum of pollen-collecting bees, leading to ecological generalization.

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Bee-Mediated Selection Favors Floral Sex Specialization in a Heterantherous Species: Strategies to Solve the Pollen Dilemma

Cited by 7 publications

References 78 publications

Using geometric morphometrics to determine the “fittest” floral shape: A case study in large‐flowered, buzz‐pollinated Meriania hernandoi

Using geometric morphometrics to determine the “fittest” floral shape: A case study in large‐flowered, buzz‐pollinated Meriania hernandoi

Dillenia (Dilleniaceae) pollen heteromorphy and presentation, and implications for pollination by bats

Flower morphology and plant–bee pollinator interactions are related to stamen dimorphism in Melastomataceae

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