Shuang-Quan Huang

Central China Normal University · School of Life Sciences

Background and Aims Morphological matching between flower and pollinator traits has been documented in diverse plant lineages. Indeed, the matching of corolla-tube length and pollinator-tongue length has been cited repeatedly as a classic case of coevolution. However, there are many possible evolutionary routes to trait matching. Our aim here is bo...

Premise of the study: Floral scent, usually consisting of multiple compounds, is a complex trait and its role in pollinator attraction has received increasing attention. However, it is difficult to disentangle the effect of individual floral scent compounds due to the complexity of isolating the effect of single compounds by traditional methods....

The number of angiosperms that may depend on animals for pollination has been difficult to estimate because the pollination modes of tens of thousands of species of tall trees, canopy climbers, and epiphytes, especially from the tropics, remain unknown. Ecological research over the past 50 years, however, has established a strong correlation betwee...

Premise: Those co-flowering species that have not evolved an avoidance mechanism may exhibit tolerance to heterospecific pollen (HP) deposition as an adaptive strategy to minimize any deleterious effects of HP transfer, but empirical evidence for the tolerance hypothesis remains scarce. Methods: To estimate the potential effects of heterospecifi...

Premise: Why have pollen grains evolved to be exceptionally large in some species? Pollen feeding hypothesis suggests that if the proportion of pollen amounts for feeding is reduced in a flower, the low allocation to pollen number would allow pollen grains to be larger. Methods: To examine whether species with large pollen grains experience low...

The plant-pollinator ‘arms race’ model posits that a major driver of the evolution of elongated corollas in flowers is reciprocal selection for ‘morphological fit’ between pollinator-tongue length and access distance to nectar (usually corolla-tube length). Evidence for the pollinator-mediated selection on tube length and evolution of multiple, cor...

Animal-pollinated plants have to get pollen to a conspecific stigma while protecting it from getting eaten. Touch-sensitive stamens, which are found in hundreds of flowering plants, are thought to function in enhancing pollen export and reducing its loss, but experimental tests are scarce. Stamens of Berberis and Mahonia are inserted between paired...

Floral color change in diverse plants has been thought to be a visual signal reflecting changes in floral rewards, promoting pollinator foraging efficiency as well as plant reproductive success. It remains unclear whether olfactory signals co‐vary with floral color change. We investigated the production rhythms of floral scent and nectar associated...

During the main COVID-19 global pandemic lockdown period of 2020 an impromptu set of pollination ecologists came together via social media and personal contacts to carry out standardised surveys of the flower visits and plants in gardens. The surveys involved 67 rural, suburban and urban gardens, of various sizes, ranging from 61.18° North in Norwa...

Animal-pollinated plants have to get pollen to a conspecific stigma while protecting it from getting eaten. We provide experimental evidence that touch-sensitive stamens function in (i) enhancing pollen export and (ii) reducing pollen loss to thieves. Stamens of Berberis and Mahonia are inserted between paired nectar glands and when touched by an i...

Although mechanical isolation mediated by shared pollinators has been considered as a classic model of pollinator‐mediated floral isolation in Pedicularis, a superdiverse genus in Hengduan Mountains, southwest China, there has been no empirical study of interspecific pollen flow between closely related species. We examined reproductive barriers at...

Having hundreds of big mountains, the Qinghai–Tibetan Plateau and its southern boundary, the Hengduan Mountains Region, represent one of the world's biodiversity hotspots. In the so‐called “Third Pole of the earth”, diverse effects of climate change and habitat heterogeneity could have driven the evolution of plant adaptive strategies. In this revi...

Nectar, the most common floral reward, is generally used to determine whether an orchid species involves deceptive pollination. Estimates of the deceptive pollination systems with nectarless flowers have ranged from one quarter to one third of the nearly 30,000 species of orchids. These estimates, however, are biased towards temperate-zone, usually...

The evolution of floral traits has been thought to be influenced by local, effective pollinators. However, little attention has been paid to the possibility that altitudinal variation in floral traits could be mediated by local pollinator functional groups, particularly a shift from bees to birds. Plant size, floral traits, pollinators and their po...

Premise: It has been hypothesized that pollination success in animal-pollinated dioecious plants relies on opportunistic pollinators with no discrimination against female flowers. However, empirical studies of pollinator foraging behavior and pollination effectiveness in dioecious species are few. Methods: To investigate potential pollinators in...

Angiosperm pollen grain diameter varies greatly from a few microns to over 100, but the selective forces driving the interspecific variation in pollen size remain unclear. Although both pre- and post-pollination hypotheses have been proposed, empirical evidence remains scarce. Here we propose that visits by pollen-foraging pollinators have selected...

The study of mutualistic interaction networks has led to valuable insights into ecological and evolutionary processes. However, our understanding of network structure may depend upon the temporal scale at which we sample and analyze network data. To date, we lack a comprehensive assessment of the temporal scale‐dependence of network structure acros...

In the intense solar radiation of an alpine climate, small black bees often experience extremely high thoracic temperatures when they are foraging on flowers, but flies forage at lower temperatures. To explore the hypothesis that seed set could be depressed by transient dehydration of pollen at the high temperatures reached by hot bees foraging in...

Resource allocation to female and male function may vary among individual plants in species with variable sex expression. Size-dependent sex allocation has been proposed in hermaphrodites, in which female-biased allocation may increase with plant size. In many hermaphrodites with large floral displays, however, later-produced flowers tend to be fun...

Bees are often considered to be effective pollinators in both agricultural and natural ecosystems but could be ineffective pollinators in that they collect large quantities of pollen for food provision but deliver little to stigmas. Male bees do not collect pollen to feed larvae, and their pollination role has been underappreciated. Here we compare...

Orchids are globally distributed, a feature often attributed to their tiny dustlike seeds. They were ancestrally terrestrial but in the Eocene expanded into tree canopies, with some lineages later returning to the ground, providing an evolutionarily replicated system. Because seeds are released closer to the ground in terrestrial species than in ep...

Although plant species with either animal or wind pollination modes are widespread and usually sympatric in nature, the degree of pollen interference from wind‐pollinated species on animal‐pollinated species remains little known. Conifer trees generally release a huge number of pollen grains into the air, floating into our noses and sometimes causi...

Co‐flowering plants may commonly experience interspecific pollination. It remains unknown, however, whether interspecific pollination is a largely stochastic process or consistent enough over years to exert selection for traits that can reduce interspecific pollination or ameliorate its deleterious effects on reproduction. To assess the likelihood...

Visual signals attractive to friends may also attract enemies. The bright colors of anthers and pollen have generally been thought to attract pollinators. We hypothesize that visual crypsis of anthers, and particularly pollen, should be favored in flowering plants because protection from pollen collectors reduces the loss of male gametes. To unders...

Many bees are effective pollen collectors; however, pollen grains collected by bees for larval food are lost for plant sexual reproduction. Recognition of these conflicting interests between bees and flowers is essential for understanding of reproduction for both bees and flowers [1-3]. Plant defense compounds in pollen may function to reduce polle...

Coevolution refers to evolutionary changes in the traits of two or more interacting species caused by reciprocal natural selection. Geographic mosaic theory of coevolution (GMC) proposes that the dynamics of coevolution between pairs or group of species often occur at different geographic scales. There are three hypotheses on the coevolutionary pro...

Natural selection is one of the most important components of organic evolution, while the concept of coevolution proposes that reciprocal selection generated by interacting species could also drive their organic evolution. Formally raised in 1964, the concept of coevolution has extensively developed, but been misused or even abused. Although contin...

It has been hypothesized that intense metabolism of nectar‐inhabiting yeasts (NIYs) may change nectar chemistry including volatile profile which may affect pollinator foraging behaviours and consequently plant fitness. However, empirical evidence for the plant‐microbe‐pollinator interactions remains little known. To test this hypothesis, we use a b...

Backgrounds and Aims Gain or loss of floral nectar, an innovation in floral traits, has occurred in diverse lineages of flowering plants, but the causes of reverse transitions (gain of nectar) remain unclear. Phylogenetic studies show multiple gains and losses of floral nectar in the species-rich genus Pedicularis. Here we explore how experimental...

Pollen grains can be dispersed singly or variously aggregated in groups. Whether the evolution of pollen aggregation is driven by the pollinator remains unexplored. We hypothesize that an extensive pollen aggregation is favored under a scarcity of pollinators. Variation in pollen aggregation by viscin threads in 13 Rhododendron species was measured...

Sexual reproduction of seed plants depends largely on pollen transfer. The pollination service provided by pollinators for wild plants and managed crops is one of the most crucial ecological processes on our planet, as it plays an essential role in sustaining biodiversity and crop production. Factors such as agricultural intensification, habitat fr...

Backgrounds and aims: Gain or loss of floral nectar, an innovation in floral traits, has occurred in diverse lineages of flowering plants, but the causes of reverse transitions (gain of nectar) remain unclear. Phylogenetic studies show multiple gains and losses of floral nectar in the species-rich genus Pedicularis. Here we explore how experimenta...

Aims Interspecific and intraspecific variation in flower color in natural populations provides an opportunity for us to understand the evolution and maintenance of diversity of floral traits. Compared to corolla color, little is known about the color polymorphism of sexual organs in flowering plants. To explore evolutionary transitions of androeciu...

Non-native plant invasion imposes great threats to global diversity and ecological safety, and now is a hot-spot of ecological studies. Understanding the reproductive strategies of invasive plants could provide insights into the invasion mechanisms and be helpful for proposing prevention and control strategies. Non-native invasive plants generally...

Buckwheat is a pseudo-cereal with high nutritional and officinal value, a food crop outside of Poaceae. Cultivated buckwheat includes two species: sweet or common buckwheat (Fagopyrum esculentum), a self-incompatible, distylous annual and bitter or tartary buckwheat (F. tartaricum), a self-compatible, ho-mostylous annual herb; the former depends on...

Loss of local, effective pollinators may potentially limit plant reproductive success but the plant‐pollinator interactions could be rescued if the plant does not reject other pollen vectors. Firmiana kwangsiensis (Malvaceae) is an endangered tree endemic to limestone area, South China. Although its preservation status is listed as “Critically Enda...

Premise of the study: Heterostyly, the reciprocal positioning of stigmas and anthers in different floral morphs, has long been thought to promote intermorph pollination. However, extensive intramorph pollination occurs commonly in heterostylous species, leading to recurrent questions about the functional and evolutionary significance of heterostyl...

Flower color polymorphism is relatively uncommon in natural flowering plants, suggesting that maintenance of different color morphs within populations is difficult. To address the selective mechanisms shaping pollen-color dimorphism, pollinator preferences and reproductive performance were studied over three years in Epimedium pubescens in which so...

Plant stigmas and bee pollinators are competitors for pollen. Pollen placed on a pollinator’s body can be picked up by conspecific stigmas or it can be collected by the pollinator as food. Hypothetically, one solution is for pollen to be placed on ‘safe sites’ on the pollinator’s body, sites where the pollinator cannot easily remove it, leaving the...

When insect activity is limited at low temperature, birds may be comparatively more important pollinators than insects for flowering plants. It has been thought that many large-flowered Rhododendron species are pollinated by local birds in the Himalayan regions because most of these species flower in spring at high elevation with cool atmospheric t...

Premise of the study: Documenting trait transitions among species with dimorphic flowers can help to test whether similar patterns of selection are responsible for divergence in floral traits among different species. Heterostyly is thought to promote outcrossing. Theory suggests that the evolutionary transition from heterostylous to homostylous fl...

The association between plants with long corolla tubes and pollinators with long tongues has evolved repeatedly in diverse pollination systems. However, the morphogenesis of long corolla tubes involved in diverse plant groups remains largely unexplored, limiting our understanding of the evolution and maintenance of long corolla tubes. Corolla tubes...

Premise of the study: It has been hypothesized that two flower types permit flexible allocation of resources to female and male functions, yet empirical evidence for the sex-allocation hypothesis remains scarce in gynomonoecious species. To characterize resource allocation to pistillate and perfect flowers and allocation of perfect flowers between...

Premise of the study: Properties of floral nectar have been used to predict if a plant species is pollinated by birds. To see whether winter-flowering plants evolve nectar properties corresponding to bird pollinators, nectar properties of several Camellia species (including the golden-flowered tea), as well as the role of floral visitors as effect...

Backgrounds and aims: Floral traits that attract pollinators may also attract seed predators, which, in turn, may generate conflicting natural selection on such traits. Although such selection trade-offs are expected to vary geographically, few studies have investigated selection mediated by pollinators and seed predators across a geographic mosai...

Interspecific hybridization is widespread among plants; nevertheless, pre- and post-zygotic isolating mechanisms may maintain species integrity for species in sympatry despite some gene flow. Interspecific hybridization and potential isolating barriers were evaluated between co-flowering Silene asclepiadea and S. yunnanensis in an alpine community...

It remains unclear how related co‐flowering species with shared pollinators minimize reproductive interference, given that the degree of interspecific pollen flow and its consequences are little known in natural communities. Differences in pollen size in six Pedicularis species with different style lengths permit us to measure heterospecific pollen...

Pollinators visiting multiple plant species may cause heterospecific pollen transfer (HPT). To test a null model that more pollinator interspecific moves result in higher HPT among interacting species, we quantified the comparative magnitudes of the two networks involving 14 co-flowering species in an alpine meadow in the eastern Himalaya, southwes...

Darwin proposed that pollen size should be positively correlated with stigma depth rather than style length among species given that pollen tubes first enter the stigma autotrophically, then grow through the style heterotrophically. However, studies often show a positive relationship between pollen size and style length. Five floral traits were obs...

1. Although thermoregulation by large bees in cool climates has been well studied, less is known about the very different thermoregulatory strategies of small bees, especially those subjected to heat stress. 2. Studies were carried out on small (<20mg fresh weight), dark-coloured, solitary bees (mostly halictids and hylaeine colletids) experiencing...

Plant-pollinator interactions can be highly variable across years in natural communities. Although variation in the species composition and its basic structure has been investigated to understand the dynamic nature of pollination network, little is known about the temporal dynamic of interaction strength between the same plant and pollinator specie...

The evolution of long corolla tubes has been hypothesized to be driven by long-tongued pollinators. Corolla tubes in Pedicularis species can be longer than 10 cm which may function as flower stalks to increase visual attractiveness to pollinators because these species provide no nectar and are pollinated by bumblebees. The corolla tube length was m...

Relative allocation to female and male function in hermaphroditic species often departs from strict equisexuality. Increased femaleness with plant size in animal-pollinated species has been proposed in theory and demonstrated in empirical studies. However, such size-dependent sex allocation (SDS) has not been observed in some insect-pollinated spec...

Aims Distyly has been regarded as an adaptation to improve compatible pollination between two floral morphs with reciprocal herkogamy. The hypothesis that the different positions of anthers and stigmas within flowers as well as their reciprocal position between morphs, reduce the probability of self pollination raised by Darwin has been rarely test...

Aims When sympatric flowering plant species in a natural community share pollinators, study of plant–plant interactions via interspecific pollen transfer (IPT) is essential for understanding species coexistence. However, little is known about the extent of IPT between interactive species and its causes.

Aims Floral longevity, the duration that a flower remains open and functional, varies greatly among species. Variation in floral longevity has been considered to be optimal strategy for resource allocation under different ecological conditions, mainly determined by the rates of pollination and cost of flower maintenance. However, it is unclear whet...

Aims The hypothesis of predator satiation has been proposed to explain mast fruiting in various flowering plants. It considers that the simultaneous production of large numbers of seeds by a plant population reduces the risk of seed predation for each individual. Orchids produce huge numbers of seeds per fruit and rarely experience seed predation....

Aims The calyx, the outermost whorl of a flower (usually green), has been considered to function to protect flowers. In some species, however, calyces are colorful and retained during seed development. Limonium species have been exploited as cut flower crops because the calyces persist for several months after the corolla has closed. To explore the...

Floral herbivory may have deleterious effects on the reproductive success of flowering plants. However, plants may evolve floral traits that allow them to defend against herbivory in particular conditions. A bumblebee-pollinated alpine herb, Pedicularis rex (Orobanchaceae), endemic to southwest China, has cup-like bracts that fill with rainwater, w...

Compared with self-incompatible (SI) species, species that shift to self-compatibility (SC) are more likely to colonize a new habitat. Self-incompatibility and fruit-set failure have been widely reported in European populations of Linnaea borealis (twinflower), whereas at the eastern margin of its North American distribution it showed potential SC....

Background and Aims Buzz pollination involves explosive pollen release in response to vibration, usually by bees. The mechanism of pollen release is poorly understood, and it is not clear which component of vibration (acceleration, frequency, displacement or velocity) is critical; the role of buzz frequency has been particularly controversial. This...

The pollination efficiency hypothesis has long been proposed as an explanation for interspecific variation in pollen–ovule (P:O) ratios. However, no empirical study on P:O ratios has directly and quantitatively measured pollen transfer efficiency (PE). Here, we use a PE index, defined as the proportion of pollen grains removed from anthers that are...

Background and AimsSpatial (herkogamy) and temporal (dichogamy) separation of pollen presentation and stigma receptivity have been interpreted as reducing interference between male and female functions in hermaphroditic flowers. However, spatial separation leads to a potential conflict: reduced pollination accuracy, where pollen may be placed in a...

Premise of research. The rush family (Juncaceae) is most often described as wind pollinated. However, flowers in the family have pollen in tetrads and numerous ovules, both unusual features for anemophilous plants. Here, we investigate evidence for wind and animal pollination in the alpine rush Juncus allioides in Yunnan Province, southwest China....

Background: Floral longevity has been assumed to reflect a balance between the fitness gain through increased pollination and the cost of flower maintenance. Question: Is there variation in the amount of resources allocated to male and female functions within flowers? Does floral longevity vary with temporal variation in floral sex allocation? Orga...

Gynomonoecy, a sexual system in which plants have both pistillate (female) flowers and perfect (hermaphroditic) flowers, occurs in at least 15 families, but the differential reproductive strategies of the two flower morphs within one individual remain unclear. Racemes of E remurus anisopterus ( X anthorrhoeaceae) have basal pistillate and distal pe...

Background and AimsInterest in pollinator-mediated evolutionary divergence of flower phenotype and speciation in plants has been at the core of plant evolutionary studies since Darwin. Specialized pollination is predicted to lead to reproductive isolation and promote speciation among sympatric species by promoting partitioning of (1) the species of...

Recent molecular phylogenetics have indicated that American mayapple (mainly self-incompatible, SI) and Himalayan mayapple, which was considered to be self-compatible (SC), are sister species with disjunct distribution between eastern Asia and eastern North America. We test a hypothesis that the persistence of this early spring flowering herb in th...