The biomechanics of pollen release: new perspectives on the evolution of wind pollination in angiosperms

2021 ◽  
Author(s):  
David Timerman ◽  
Spencer C.H. Barrett
Keyword(s):  
Wind Pollination ◽  
Pollen Release

scholarly journals Turbulence-induced resonance vibrations cause pollen release in wind-pollinated Plantago lanceolata L. (Plantaginaceae)

2014 ◽  
Vol 11 (101) ◽  
pp. 20140866 ◽  
Author(s):  
David Timerman ◽  
David F. Greene ◽  
Javier Urzay ◽  
Josef D. Ackerman
Keyword(s):  
Resonance Frequency ◽  
Flexural Rigidity ◽  
Mechanical Energy ◽  
Plantago Lanceolata ◽  
Damping Ratio ◽  
Pollen Grains ◽  
Wind Pollination ◽  
Resonant Vibrations ◽  
Evolutionary Transitions ◽  
Pollen Release

In wind pollination, the release of pollen from anthers into airflows determines the quantity and timing of pollen available for pollination. Despite the ecological and evolutionary importance of pollen release, wind–stamen interactions are poorly understood, as are the specific forces that deliver pollen grains into airflows. We present empirical evidence that atmospheric turbulence acts directly on stamens in the cosmopolitan, wind-pollinated weed, Plantago lanceolata , causing resonant vibrations that release episodic bursts of pollen grains. In laboratory experiments, we show that stamens have mechanical properties corresponding to theoretically predicted ranges for turbulence-driven resonant vibrations. The mechanical excitation of stamens at their characteristic resonance frequency caused them to resonate, shedding pollen vigorously. The characteristic natural frequency of the stamens increased over time with each shedding episode due to the reduction in anther mass, which increased the mechanical energy required to trigger subsequent episodes. Field observations of a natural population under turbulent wind conditions were consistent with these laboratory results and demonstrated that pollen is released from resonating stamens excited by small eddies whose turnover periods are similar to the characteristic resonance frequency measured in the laboratory. Turbulence-driven vibration of stamens at resonance may be a primary mechanism for pollen shedding in wind-pollinated angiosperms. The capacity to release pollen in wind can be viewed as a primary factor distinguishing animal- from wind-pollinated plants, and selection on traits such as the damping ratio and flexural rigidity may be of consequence in evolutionary transitions between pollination systems.

scholarly journals Repeated parallel losses of inflexed stamens in Moraceae: phylogenomics and generic revision of the tribe Moreae and the reinstatement of the tribe Olmedieae (Moraceae)

2020 ◽  
Author(s):  
Elliot M. Gardner ◽  
Mira Garner ◽  
Robyn Cowan ◽  
Steven Dodsworth ◽  
Niroshini Epitawalage ◽  
...  
Keyword(s):  
New Genus ◽  
Global Distribution ◽  
Wind Pollination ◽  
Character State ◽  
New Combinations ◽  
Pollen Release ◽  
Phylogenomic Study

AbstractWe present a densely-sampled phylogenomic study of the mulberry tribe (Moreae, Moraceae), an economically important clade with a global distribution, revealing multiple losses of inflexed stamens, a character traditionally used to circumscribe Moreae. Inflexed stamens facilitate ballistic pollen release and are associated with wind pollination, and the results presented here suggest that losses of this character state may have evolved repeatedly in Moraceae. Neither Moreae nor several of its major genera (Morus, Streblus, Trophis) were found to be monophyletic. A revised system for a monophyletic Moreae is presented, including the reinstatement of the genera Ampalis, Maillardia, Taxotrophis, and Paratrophis, and the recognition of the new genus Afromorus, based on Morus subgenus Afromorus. Pseudostreblus is reinstated and transferred to the Parartocarpeae, and Sloetiopsis is reinstated and transferred to the Dorstenieae. The tribe Olmediae is reinstated, replacing the Castilleae, owing to the reinstatement of the type genus Olmedia, and its exclusion from Moreae. Streblus s.s. is excluded from Moreae and transferred to the Olmediae, which is characterized primarily by involucrate inflorescences without regard to stamen position. Eight new combinations are made.

scholarly journals Divergent selection on the biomechanical properties of stamens under wind and insect pollination

2018 ◽  
Vol 285 (1893) ◽  
pp. 20182251 ◽  
Author(s):  
David Timerman ◽  
Spencer C. H. Barrett
Keyword(s):  
Wind Tunnel ◽  
Biomechanical Properties ◽  
Experimental Manipulation ◽  
Biomechanical Analysis ◽  
Male Reproductive Success ◽  
Wind Pollination ◽  
Insect Pollination ◽  
Strong Negative Correlation ◽  
Transitional State ◽  
Pollen Release

Wind pollination has evolved from insect pollination in numerous angiosperm lineages and is associated with a characteristic syndrome of morphological traits. The traits initiating transitions to wind pollination and the ecological drivers involved are poorly understood. Here, we examine this problem in Thalictrum pubescens , an ambophilous (insect and wind pollination) species that probably represents a transitional state in the evolution of wind pollination. We investigated wind-induced pollen release by forced harmonic motion by measuring stamen natural frequency ( f n ), a key vibration parameter, and its variability among nine populations. We assessed the repeatability of f n over consecutive growing seasons, the effect of this parameter on pollen release in a wind tunnel, and male reproductive success in the field using experimental manipulation of the presence or absence of pollinators. We found significant differences among populations and high repeatability within genotypes in f n . The wind tunnel assay revealed a strong negative correlation between f n and pollen release. Siring success was greatest for plants with lower f n when pollinators were absent, but this advantage diminished when pollinators were present. Our biomechanical analysis of the wind–flower interface has identified f n as a key trait for understanding early stages in the transition from insect to wind pollination.

scholarly journals Comparative analysis of pollen release biomechanics inThalictrum: implications for evolutionary transitions between animal and wind pollination

2019 ◽  
Vol 224 (3) ◽  
pp. 1121-1132 ◽  
Author(s):  
David Timerman ◽  
Spencer C. H. Barrett
Keyword(s):  
Comparative Analysis ◽  
Wind Pollination ◽  
Evolutionary Transitions ◽  
Pollen Release

scholarly journals Understanding plant reproductive diversity

2010 ◽  
Vol 365 (1537) ◽  
pp. 99-109 ◽  
Author(s):  
Spencer C. H. Barrett
Keyword(s):  
Reproductive Biology ◽  
Flowering Plants ◽  
Future Research ◽  
Wind Pollination ◽  
Evolutionary Patterns ◽  
Evolutionary Transitions ◽  
Floral Diversity ◽  
Self Fertilization ◽  
Personal Reflections ◽  
Animal Pollination

Flowering plants display spectacular floral diversity and a bewildering array of reproductive adaptations that promote mating, particularly outbreeding. A striking feature of this diversity is that related species often differ in pollination and mating systems, and intraspecific variation in sexual traits is not unusual, especially among herbaceous plants. This variation provides opportunities for evolutionary biologists to link micro-evolutionary processes to the macro-evolutionary patterns that are evident within lineages. Here, I provide some personal reflections on recent progress in our understanding of the ecology and evolution of plant reproductive diversity. I begin with a brief historical sketch of the major developments in this field and then focus on three of the most significant evolutionary transitions in the reproductive biology of flowering plants: the pathway from outcrossing to predominant self-fertilization, the origin of separate sexes (females and males) from hermaphroditism and the shift from animal pollination to wind pollination. For each evolutionary transition, I consider what we have discovered and some of the problems that still remain unsolved. I conclude by discussing how new approaches might influence future research in plant reproductive biology.

scholarly journals Connective appendages in Huberia bradeana (Melastomataceae) affect pollen release during buzz pollination

Plant Biology ◽  
2021 ◽  
Author(s):  
T. Bochorny ◽  
L. F. Bacci ◽  
A. S. Dellinger ◽  
F. A. Michelangeli ◽  
R. Goldenberg ◽  
...  
Keyword(s):  
Buzz Pollination ◽  
Pollen Release

Wind pollination and reproductive assurance inLinanthus parviflorus(Polemoniaceae), a self-incompatible annual

1999 ◽  
Vol 86 (7) ◽  
pp. 948-954 ◽  
Author(s):  
Carol Goodwillie
Keyword(s):  
Wind Pollination ◽  
Reproductive Assurance

Investigation of pollen release by poricidal anthers using mathematical billiards

2021 ◽  
Vol 104 (3) ◽  
Author(s):  
Matheus Hansen ◽  
Gabriel C. Lanes ◽  
Vinícius L. G. Brito ◽  
Edson D. Leonel
Keyword(s):  
Pollen Release ◽  
Poricidal Anthers

Inflorescence development and seed production in Lolium spp. × Festuca pratensis tetraploid hybrids

1975 ◽  
Vol 85 (2) ◽  
pp. 301-307 ◽  
Author(s):  
P. Cremades ◽  
E. W. Bean
Keyword(s):  
Seed Production ◽  
Lolium Perenne ◽  
Lolium Multiflorum ◽  
Pollen Viability ◽  
Festuca Pratensis ◽  
Inflorescence Development ◽  
Tetraploid Hybrid ◽  
Pollen Release ◽  
Sufficient Variation ◽  
Reproductive Characters

SUMMARYThe reproductive development and seed production characters of a Lolium multiflorum × Festuca pratensis tetraploid hybrid and a Lolium perenne × Festuca pratensis tetraploid hybrid were compared with those of their tetraploid parental cultivars. Experiments were carried out under glasshouse and natural conditions; single plants were studied as only small quantities of seed were available from the breeder. The lowtemperature/short-day requirements for inflorescence induction of the two hybrids were in between those of the corresponding parental species. The variance of the date at which vegetative primordia changed to the reproductive condition was greater in the hybrids than in the parental cultivars, but the variance of the dates of inflorescence emergence were similar for the hybrids and parental cultivars. Inflorescences ranged from the Lolium type with only sessile spikelets to the Festuca type with primary branches. Inner glumes, which are absent in the Lolium parents but present in Festuca pratensis, were found in the hybrids, though not in all spikelets. In the Lolium perenne × Festuca pratensis hybrid pollen release, potential pollen viability and floret fertility were low, but the Lolium multiflorum × Festuca pratensis hybrid produced large amounts of pollen with a higher potential viability and had floret fertilities similar to those of its two parental cultivars. There was sufficient variation in reproductive characters for further selection, particularly in the Lolium perenne × Festuca pratensis hybrid.

scholarly journals Floral Biology and Seed Production in Cultivated North American Ginseng (Panax quinquefolius)

2000 ◽  
Vol 125 (5) ◽  
pp. 567-575 ◽  
Author(s):  
Cayetana Schluter ◽  
Zamir K. Punja
Keyword(s):  
Seed Production ◽  
North American ◽  
Age Groups ◽  
Morphological Characteristics ◽  
Floral Biology ◽  
American Ginseng ◽  
Panax Quinquefolius ◽  
Flowering Period ◽  
Pollination Success ◽  
Pollen Release

Morphological characteristics of flowers, duration of flowering, degree of self-pollination, and extent of berry and seed production in North American ginseng (Panax quinquefolius L.) were studied under controlled environmental conditions as well as under field conditions. A comparison was also made between plants of 3 and 4 years of age at two field locations. The duration of flowering was ≈4 weeks and was similar in plants of both age groups grown in the two environments; however, 4-year-old plants produced an average of 40% more flowers (≈100 per plant in total) compared to 3-year-old plants. Flowers were comprised of five greenish-colored petals, five stamens, and an inferior ovary consisting of predominantly two fused carpels and stigmatic lobes. Anthers dehisced in staggered succession within individual flowers, and flowering began with the outermost edge of the umbel and proceeded inwards. At any given time during the 4-week flowering period, ≈10% of the flowers in an umbel had recently opened and were producing pollen. Stigma receptivity was associated with separation of the stigmatic lobes; this occurred at some time after pollen release. Growth of pollen tubes through the style in naturally pollinated flowers was most evident when the stigmatic lobes had separated. The proportion of flowers that developed into mature berries (pollination success rate) was in the range of 41% to 68% for both 3-year-old and 4-year-old plants. However, when the inflorescence was bagged during the flowering period, berry formation was increased by 13% to 21% in 4-year-old plants, depending on location. A majority of the berries (92% to 99%) contained one or two seeds in an almost equal frequency, with the remaining berries containing three seeds. In 4-year-old plants, the frequency of two-seeded berries was increased by ≈13% by bagging the inflorescence. These observations indicate that P. quinquefolius is highly self-fertile and that several physiological and environmental factors can affect seed production.

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