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Abrahamczyk S, Struck JH, Weigend M. The best of two worlds: ecology and evolution of ambophilous plants. Biol Rev Camb Philos Soc 2023; 98:391-420. [PMID: 36270973 DOI: 10.1111/brv.12911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 10/05/2022] [Accepted: 10/05/2022] [Indexed: 11/29/2022]
Abstract
Ambophily, the mixed mode of wind and insect pollination is still poorly understood, even though it has been known to science for over 130 years. While its presence has been repeatedly inferred, experimental data remain regrettably rare. No specific suite of morphological or ecological characteristics has yet been identified for ambophilous plants and their ecology and evolution remain uncertain. In this review we summarise and evaluate our current understanding of ambophily, primarily based on experimental studies. A total of 128 ambophilous species - including several agriculturally important crops - have been reported from most major habitat types worldwide, but this probably represents only a small subset of ambophilous species. Ambophilous species have evolved both from wind- and insect-pollinated ancestors, with insect-pollinated ancestors mostly representing pollination by small, generalist flower visitors. We compiled floral and reproductive traits for known ambophilous species and compared our results to traits of species pollinated either by wind or by small generalist insects only. Floral traits were found to be heterogeneous and strongly overlap especially with those of species pollinated by small generalist insects, which are also the prominent pollinator group for ambophilous plants. A few ambophilous species are only pollinated by specialised bees or beetles in addition to pollination by wind. The heterogeneity of floral traits and high similarity to generalist small insect-pollinated species lead us to conclude that ambophily is not a separate pollination syndrome but includes species belonging to different insect- as well as wind-pollination syndromes. Ambophily therefore should be regarded as a pollination mode. We found that a number of ecological factors promoted the evolution of ambophily, including avoidance of pollen limitation and self-pollination, spatial flower interference and population density. However, the individual ecological factors favouring the transition to ambophily vary among species depending on species distribution, habitat, population structure and reproductive system. Finally, a number of experimental studies in combination with observations of floral traits of living and fossil species and dated phylogenies may indicate evolutionary stability. In some clades ambophily has likely prevailed for millions of years, for example in the castanoid clade of the Fagaceae.
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Affiliation(s)
- Stefan Abrahamczyk
- Botany Department, State Museum of Natural History Stuttgart, Rosenstein 1, 70191, Stuttgart, Germany
- Nees Institute for Biodiversity of Plants, University of Bonn, Meckenheimer Allee 170, 53113, Bonn, Germany
| | - Jan-Hendrik Struck
- Nees Institute for Biodiversity of Plants, University of Bonn, Meckenheimer Allee 170, 53113, Bonn, Germany
| | - Maximilian Weigend
- Nees Institute for Biodiversity of Plants, University of Bonn, Meckenheimer Allee 170, 53113, Bonn, Germany
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Zhu QQ, Xue C, Sun L, Zhong X, Zhu XX, Ren Y, Zhang XH. The diversity of elaborate petals in Isopyreae (Ranunculaceae): a special focus on nectary structure. PROTOPLASMA 2023; 260:437-451. [PMID: 35760912 DOI: 10.1007/s00709-022-01787-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 06/18/2022] [Indexed: 05/25/2023]
Abstract
Elaborate petals are highly diverse in morphology, structure, and epidermal differentiation and play a key role in attracting pollinators. There have been few studies on the elaborate structure of petals in the tribe Isopyreae (Ranunculaceae). Seven genera in Isopyreae (Aquilegia, Semiaquilegia, Urophysa, Isopyrum, Paraquilegia, Dichocarpum, and Leptopyrum) have petals that vary in morphology, and two genera (Enemion and Thalictrum) have no petals. The petals of nine species belonged to 7 genera in the tribe were studied to reveal their nectary structure, epidermal micromorphology and ancestral traits. The petal nectaries of Isopyreae examined in this study were located at the tip of spurs (Aquilegia yabeana and A. rockii), or the bottom of shallow sacs (Semiaquilegia adoxoides, Urophysa henryi, Isopyrum manshuricum, and Paraquilegia microphylla), a cup-shaped structure (Dichocarpum fargesii) and a bilabiate structure (Leptopyrum fumarioides). The petal nectary of eight species in Isopyreae (except A. ecalcarata) was composed of secretory epidermis, nectary parenchyma, and vascular tissues, and some sieve tubes reached the secretory parenchyma cells. Among the eight species with nectaries examined in the present study, A. yabeana had the most developed nectaries, with 10-15 layers of secretory parenchyma cells. The epidermal cells of mature petals of the nine species were divided into 11 types. Among these 11 types, there were two types of secretory cells and two types of trichomes. Aquilegia yabeana and A. rockii had the highest number of cell types (eight types), and I. manshuricum and L. fumarioides had the lowest number of cell types (three types). Aquilegia ecalcarata had no secretory cells, and the papillose conical polygonal secretory cells of D. fargesii were different from those of the other seven species with nectaries. Trichomes were found only in Aquilegia, Semiaquilegia, Urophysa, and Paraquilegia. The ancestral mode of nectar presentation in Isopyreae was petals with hidden nectar (70.58%). The different modes of nectar presentation in petals may reflect adaptations to different pollinators in Isopyreae.
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Affiliation(s)
- Qing-Qing Zhu
- Key Laboratory of Medicinal Plant Resource and Natural Pharmaceutical Chemistry of Ministry of Education, Shaanxi Normal University, Xi'an, 710062, China
- College of Life Science, Shaanxi Normal University, Xi'an, 710062, China
| | - Cheng Xue
- Key Laboratory of Medicinal Plant Resource and Natural Pharmaceutical Chemistry of Ministry of Education, Shaanxi Normal University, Xi'an, 710062, China
| | - Li Sun
- Key Laboratory of Medicinal Plant Resource and Natural Pharmaceutical Chemistry of Ministry of Education, Shaanxi Normal University, Xi'an, 710062, China
| | - Xin Zhong
- Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai, 201602, China
| | - Xin-Xin Zhu
- College of Life Sciences, Xinyang Normal University, Xinyang, 46400, China
| | - Yi Ren
- Key Laboratory of Medicinal Plant Resource and Natural Pharmaceutical Chemistry of Ministry of Education, Shaanxi Normal University, Xi'an, 710062, China
| | - Xiao-Hui Zhang
- Key Laboratory of Medicinal Plant Resource and Natural Pharmaceutical Chemistry of Ministry of Education, Shaanxi Normal University, Xi'an, 710062, China.
- College of Life Science, Shaanxi Normal University, Xi'an, 710062, China.
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Aljiboury AA, Friedman J. Mating and fitness consequences of variation in male allocation in a wind-pollinated plant. Evolution 2022; 76:1762-1775. [PMID: 35765717 DOI: 10.1111/evo.14544] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 04/26/2022] [Accepted: 05/04/2022] [Indexed: 01/22/2023]
Abstract
In hermaphrodites, the allocation of resources to each sex function can influence fitness through mating success. A prediction that arises from sex allocation theory is that in wind-pollinated plants, male fitness should increase linearly with investment of resources into male function but there have been few empirical tests of this prediction. In a field experiment, we experimentally manipulated allocation to male function in Ambrosia artemisiifolia (common ragweed) and measured mating success in contrasting phenotypes using genetic markers. We investigated the effects of morphological traits and flowering phenology on male siring success, and on the diversity of mates. Our results provide evidence for a linear relation between allocation to male function, mating, and fitness. We find earlier onset of male flowering time increases reproductive success, whereas later flowering increases the probability of mating with diverse individuals. Our study is among the first empirical tests of the prediction of linear male fitness returns in wind-pollinated plants and emphasizes the importance of a large investment into male function by wind-pollinated plants and mating consequences of temporal variation in sex allocation.
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Affiliation(s)
- Abrar A Aljiboury
- Department of Biology, Syracuse University, Syracuse, New York, 13244
| | - Jannice Friedman
- Department of Biology, Syracuse University, Syracuse, New York, 13244.,Department of Biology, Queen's University, Kingston, Canada, K7L 3N6
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Jankauski M, Ferguson R, Russell A, Buchmann S. Structural dynamics of real and modelled Solanum stamens: implications for pollen ejection by buzzing bees. J R Soc Interface 2022; 19:20220040. [PMID: 35259960 PMCID: PMC8905162 DOI: 10.1098/rsif.2022.0040] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
An estimated 10% of flowering plant species conceal their pollen within tube-like anthers that dehisce through small apical pores (poricidal anthers). Bees extract pollen from poricidal anthers through a complex motor routine called floral buzzing, whereby the bee applies vibratory forces to the flower stamen by rapidly contracting its flight muscles. The resulting deformation depends on the stamen's natural frequencies and vibration mode shapes, yet for most poricidal species, these properties have not been sufficiently characterized. We performed experimental modal analysis on Solanum elaeagnifolium stamens to quantify their natural frequencies and vibration modes. Based on morphometric and dynamic measurements, we developed a finite-element model of the stamen to identify how variable material properties, geometry and bee weight could affect its dynamics. In general, stamen natural frequencies fell outside the reported floral buzzing range, and variations in stamen geometry and material properties were unlikely to bring natural frequencies within this range. However, inclusion of bee mass reduced natural frequencies to within the floral buzzing frequency range and gave rise to an axial-bending vibration mode. We hypothesize that floral buzzing bees exploit the large vibration amplification factor of this mode to increase anther deformation, which may facilitate pollen ejection.
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Affiliation(s)
- Mark Jankauski
- Department of Mechanical and Industrial Engineering, Montana State University, Bozeman, MT, USA
| | - Riggs Ferguson
- Department of Mechanical and Industrial Engineering, Montana State University, Bozeman, MT, USA
| | - Avery Russell
- Department of Biology, Missouri State University, Springfield, MO, USA
| | - Stephen Buchmann
- Department of Ecology and Evolutionary Biology,, University of Arizona, Tucson, AZ, USA.,Department of Entomology, University of Arizona, Tucson, AZ, USA
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Mitchell N, Piatczyc NP, Wang DD, Edwards J. High-speed video and plant ultrastructure define mechanisms of gametophyte dispersal. APPLICATIONS IN PLANT SCIENCES 2022; 10:e11463. [PMID: 35495193 PMCID: PMC9039801 DOI: 10.1002/aps3.11463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 12/15/2021] [Accepted: 01/10/2022] [Indexed: 05/06/2023]
Abstract
Dispersal of gametophytes is critical for land plant survivorship and reproduction. It defines potential colonization and geographical distribution as well as genetic mixing and evolution. C. T. Ingold's classic works on Spore Discharge in Land Plants and Spore Liberation review mechanisms for spore release and dispersal based on real-time observations, basic histology, and light microscopy. Many mechanisms underlying spore liberation are explosive and have evolved independently multiple times. These mechanisms involve physiological processes such as water gain and loss, coupled with structural features using different plant tissues. Here we review how high-speed video and analyses of ultrastructure have defined new biomechanical mechanisms for the dispersal of gametophytes through the dissemination of haploid diaspores, including spores, pollen, and asexual reproductive propagules. This comparative review highlights the diversity and importance of rapid movements in plants for dispersing gametophytes and considerations for using combinations of high-speed video methods and microscopic techniques to understand these dispersal movements. A deeper understanding of these mechanisms is crucial not only for understanding gametophyte ecology but also for applied engineering and biomimetic applications used in human technologies.
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Affiliation(s)
- Nora Mitchell
- Department of BiologyUniversity of Wisconsin–Eau ClaireEau Claire54701WisconsinUSA
| | - Nancy P. Piatczyc
- Biology DepartmentWilliams College, WilliamstownMassachusetts01267USA
| | - Darren D. Wang
- Biology DepartmentWilliams College, WilliamstownMassachusetts01267USA
| | - Joan Edwards
- Biology DepartmentWilliams College, WilliamstownMassachusetts01267USA
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Vallejo-Marín M. How and why do bees buzz? Implications for buzz pollination. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:1080-1092. [PMID: 34537837 PMCID: PMC8866655 DOI: 10.1093/jxb/erab428] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
Buzz pollination encompasses the evolutionary convergence of specialized floral morphologies and pollinator behaviour in which bees use vibrations (floral buzzes) to remove pollen. Floral buzzes are one of several types of vibrations produced by bees using their thoracic muscles. Here I review how bees can produce these different types of vibrations and discuss the implications of this mechanistic understanding for buzz pollination. I propose that bee buzzes can be categorized according to their mode of production and deployment into: (i) thermogenic, which generate heat with little mechanical vibration; (ii) flight buzzes which, combined with wing deployment and thoracic vibration, power flight; and (iii) non-flight buzzes in which the thorax vibrates but the wings remain mostly folded, and include floral, defence, mating, communication, and nest-building buzzes. I hypothesize that the characteristics of non-flight buzzes, including floral buzzes, can be modulated by bees via modification of the biomechanical properties of the thorax through activity of auxiliary muscles, changing the rate of activation of the indirect flight muscles, and modifying flower handling behaviours. Thus, bees should be able to fine-tune mechanical properties of their floral vibrations, including frequency and amplitude, depending on flower characteristics and pollen availability to optimize energy use and pollen collection.
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Affiliation(s)
- Mario Vallejo-Marín
- Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, UK
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Timerman D, Barrett SCH. The biomechanics of pollen release: new perspectives on the evolution of wind pollination in angiosperms. Biol Rev Camb Philos Soc 2021; 96:2146-2163. [PMID: 34076950 DOI: 10.1111/brv.12745] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 11/30/2022]
Abstract
Evolutionary transitions from animal to wind pollination have occurred repeatedly during the history of the angiosperms, but the selective mechanisms remain elusive. Here, we propose that knowledge of pollen release biomechanics is critical for understanding the ecological and evolutionary processes underpinning this shift in pollination mode. Pollen release is the critical first stage of wind pollination (anemophily) and stamen properties are therefore likely to be under strong selection early in the transition. We describe current understanding of pollen release biomechanics to provide insights on the phenotypic and ecological drivers of wind pollination. Pollen release occurs when detachment forces dominate resistive forces retaining pollen within anthers. Detachment forces can be active or passive depending on whether they require energy input from the environment. Passive release is more widespread in anemophilous species and involves processes driven by steady or unsteady aerodynamic forces or turbulence-induced vibrations that shake pollen from anthers. We review empirical and theoretical studies suggesting that stamen vibration is likely to be a key mechanism of pollen release. The vibration response is governed by morphological and biomechanical properties of stamens, which may undergo divergent selection in the presence or absence of pollinators. Resistive forces have rarely been investigated for pollen within anthers, but are probably sensitive to environmental conditions and depend on flower age, varying systematically between animal- and wind-pollinated species. Animal and wind pollination are traditionally viewed as dichotomous alternatives because they are usually associated with strikingly different pollination syndromes. But this perspective has diverted attention from subtler, continuously varying traits which mediate the fluid dynamic process of pollen release. Reinterpreting the flower as a biomechanical entity that responds to fluctuating environmental forces may provide a promising way forward. We conclude by identifying several profitable areas for future research to obtain deeper insight into the evolution of wind pollination.
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Affiliation(s)
- David Timerman
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, M5S 3B2, Canada
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, M5S 3B2, Canada
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Arias T, Riaño‐Pachón DM, Di Stilio VS. Genomic and transcriptomic resources for candidate gene discovery in the Ranunculids. APPLICATIONS IN PLANT SCIENCES 2021; 9:e11407. [PMID: 33552749 PMCID: PMC7845765 DOI: 10.1002/aps3.11407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 12/03/2020] [Indexed: 06/12/2023]
Abstract
PREMISE Multiple transitions from insect to wind pollination are associated with polyploidy and unisexual flowers in Thalictrum (Ranunculaceae), yet the underlying genetics remains unknown. We generated a draft genome of Thalictrum thalictroides, a representative of a clade with ancestral floral traits (diploid, hermaphrodite, and insect pollinated) and a model for functional studies. Floral transcriptomes of T. thalictroides and of wind-pollinated, andromonoecious T. hernandezii are presented as a resource to facilitate candidate gene discovery in flowers with different sexual and pollination systems. METHODS A draft genome of T. thalictroides and two floral transcriptomes of T. thalictroides and T. hernandezii were obtained from HiSeq 2000 Illumina sequencing and de novo assembly. RESULTS The T. thalictroides de novo draft genome assembly consisted of 44,860 contigs (N50 = 12,761 bp, 243 Mbp total length) and contained 84.5% conserved embryophyte single-copy genes. Floral transcriptomes contained representatives of most eukaryotic core genes, and most of their genes formed orthogroups. DISCUSSION To validate the utility of these resources, potential candidate genes were identified for the different floral morphologies using stepwise data set comparisons. Single-copy gene analysis and simple sequence repeat markers were also generated as a resource for population-level and phylogenetic studies.
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Affiliation(s)
- Tatiana Arias
- School of Biological SciencesThe University of Hong KongPokfulamHong Kong
- Department of BiologyUniversity of Washington, SeattleWashington98195‐1800USA
- Present address:
Tecnológico de AntioquiaCalle 78B No. 72A220MedellínColombia
| | - Diego Mauricio Riaño‐Pachón
- Laboratory of Computational, Evolutionary and Systems BiologyCenter for Nuclear Energy in AgricultureUniversity of São PauloPiracicabaSão Paulo13416‐000Brazil
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Timerman D, Barrett SCH. Influence of local density and sex ratio on pollination in an ambophilous flowering plant. AMERICAN JOURNAL OF BOTANY 2020; 107:587-598. [PMID: 32227341 DOI: 10.1002/ajb2.1453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 01/23/2020] [Indexed: 06/10/2023]
Abstract
PREMISE Variation in local density and sex ratio in dioecious plants can affect mating success through the actions of pollen vectors, principally generalist insects or wind. Increased density and male-biased sex ratios should promote pollen transfer and seed production, but their combined effects have not been investigated for ambophilous species, which exhibit both insect and wind pollination. METHODS We manipulated density (low vs. high) and sex ratio (1:1 vs. 3:1 male-biased) in arrays of dioecious ambophilous Thalictrum pubescens. We quantified visitation rates and foraging times to examine whether pollinators exhibited sex-specific preferences and determined the seed set of arrays. RESULTS Pollinators visited more plants per foraging bout at high than low density. Visitation rates and foraging times of visitors were greater for male than for female plants but did not depend on the density or sex ratio of arrays. However, whereas solitary bees displayed a strong preference for males, hover flies were indifferent to plant sex phenotype. Solitary bees also visited significantly more plants per foraging bout than hover flies. There was a significant interaction between density and sex ratio on seed set. At low density, seed set was greater for 3:1 than for 1:1 arrays, but at high density the opposite pattern occurred. CONCLUSIONS The demographic factors we investigated had complex influences on pollinator foraging behavior and patterns of seed set. Several factors may explain our results, including the influence of density and sex ratio on pollen export from arrays, grooming by pollinators, and the contribution of wind pollination.
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Affiliation(s)
- David Timerman
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, M5S 3B2, Canada
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, M5S 3B2, Canada
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Timerman D, Barrett SCH. Comparative analysis of pollen release biomechanics in Thalictrum: implications for evolutionary transitions between animal and wind pollination. THE NEW PHYTOLOGIST 2019; 224:1121-1132. [PMID: 31172529 DOI: 10.1111/nph.15978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 05/29/2019] [Indexed: 05/11/2023]
Abstract
Transitions from animal to wind pollination have occurred repeatedly in flowering plants, driven by structural and biomechanical modifications to flowers. But the initial changes promoting wind pollination are poorly understood, especially those required to release pollen into airflows - the critical first stage of wind pollination. Using a wind tunnel, we performed a comparative study of pollen release biomechanics in 36 species of animal- and wind-pollinated Thalictrum. We quantified pollination syndromes and stamen natural frequency (fn ), a key vibration parameter, to determine if floral traits reliably predicted pollen release probability. We then investigated if pollen release was caused by wind-induced resonance vibration of stamens. We detected wind-induced stamen resonance in 91% of species and a strong effect of stamen acceleration on pollen release, inversely driven by fn . However, unlike fn , pollination syndromes did not reliably predict the probability of pollen release among species. Our results directly link fn to the capacity of stamens to release pollen by wind and suggest that structural mechanisms reducing fn are likely to be important for initiating transitions from animal to wind pollination. Our inability to predict the probability of pollen release based on pollination syndromes suggests diverse phenotypic trajectories from animal to wind pollination.
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Affiliation(s)
- David Timerman
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
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