Background & Aims: Overgrazing poses a dominant threat to the biodiversity of most grassland communities. Bees are the primary pollinator group in the grassland ecosystem. Grazing has generally negative effects on bee diversity by affecting floral and nesting resources in grassland communities. However, in communities with long grazing history and reasonable grazing management, grazing may have a positive or neutral impact on bee diversity. Therefore, how grazing affects bee diversity and its role in ecological restoration needs further study.
Progress: In this study, we integrate the recent literature and research practice, and propose that the efficacy of bee restoration can be more accurately assessed through the integration of bee species richness, functional diversity, phylogenetic diversity and full plant-pollinator interaction networks, which provide comprehensive and quantitative information on the structure and function of grassland communities. For grasslands with low degradation, bees can be gradually recovered by effective grazing management, which uses the natural recovery potential of the communities. For grasslands with greater degradation, it is necessary to accelerate the bee restoration through active interventions on the basis of grazing management, such as sowing wildflower species that cannot migrate into the restoration area without assistance and enhancing the availability of nesting habitat for bees. To ensure that bees can obtain enough floral rewards in different flowering periods, the selection and combination of the sown flower species should take into account their roles in the pollination network, floral traits and flowering phenology.
Perspective: It is of great practical significance to investigate the mechanism of bee loss in different types of grasslands in southern and northern China, and to guide the development of targeted ecological restoration strategies for bees.

Aims: In monoecious Ficus species, fig wasps lay eggs in the ovaries to propagate their offspring while also pollinating female flowers to generate seeds after they reach the female phase figs. On the other hand, in dioecious Ficus, fig wasps lay eggs in the ovaries of male figs and pollinate female flowers in female figs, indicating their differential reproductive tasks in the male and female figs. Our study aims to investigate interspecific differences and diversity in the oviposition and pollination behaviors of pollinating fig wasps and quantify the time involved in different behaviors in female phase figs, a subject that has been scarcely studied.
Methods: We selected four partners belonging to Ceratosolen wasps and subgenus Sycomorus figs, comprising both monoecious and dioecious fig species. Initially, we determined the pollination modes by collecting anther/ovule ratios of Ficus species, observing pollination structures and behaviors of pollinating fig wasps. The length of wasp ovipositors and flower styles were measured under the microscope with a micrometer to verify their matching. Additionally, we observed and quantitatively record the searching, oviposition and pollination behaviors of Ceratosolen spp. in female phase figs using a Digital Microscope.
Results: Our study found that monoecious Ficus racemosa, dioecious F. auriculata, F. hispida and F. semicordata were actively pollinated by their respective Ceratosolen pollinating fig wasps, which exhibited an active pollination mode. The length of ovipositors and flower styles were found to be matching, with pollinating fig wasps in monoecious figs laying eggs in some female flowers for offspring reproduction and pollinating some other female flowers to produce seeds. In dioecious figs, pollinating fig wasps laid eggs in male figs to reproduce offspring and pollinated female flowers in female figs to produce seeds. Moreover, the searching, oviposition, and pollination behaviors of Ceratosolen spp. in female phase figs were diverse. In monoecious figs, pollinating fig wasps primarily laid eggs in the first six hours after entering the figs and then pollinated female flowers, with a short time cost per pollination behavior. However, in dioecious male and female figs pollinating fig wasps pollinated female flowers at the end of each oviposition behavior and then extracted the ovipositors before repeating a similar behavior. As pollinating fig wasps oviposited more times, they also pollinated female flowers more times. Nevertheless, irregularity was observed in the pollinating fig wasps’ behavior in the female figs of F. hispida and F. semicordata.
Conclusion: Our study found that the time cost of per oviposition for Ceratosolen spp. was longer than that of pollination, and the time costs of searching, oviposition and pollination behaviors varied in different reproductive systems and sexes. Our results shed light on the diversity and different patterns of pollination and oviposition behaviors of fig wasps in female phase figs, providing a valuable reference for studying the behavioral diversity of other pollinators.

Aims: The pollination behaviors of Apis cerana cerana (Acc) and Apis mellifera ligustica (Aml) have a significant meaning in maintaining ecosystem stability and improving crop yield and quality. However, their pollination behaviors are different. The aim of this study is to analyze the differences of pollinating habit and plant diversity between the two species under low temperature during the late autumn and winter periods.
Methods: We observed the pollination process of Acc and Aml, and collected the pollen in Xiasha Higher Education Campus of Hangzhou City during the late autumn and winter periods. The pollen morphology was analyzed by ordinary and scanning electron microscope, and further determined based on the gene ribulose 1,5-bisphosphate carboxylase (rbcl) amplified and DNA barcode. Finally, the diversity of pollinating plants was compared according to the pollen species during the late autumn and winter.
Results: Both Acc and Aml can pollinate the local plants during the late autumn and winter periods, but Acc had better adaptability and pollination frequency in the morning from 8:30 to 9:30 (P < 0.05). For different plants, Acc and Aml can pollinate many kinds of plant. Acc tended to collect pollen of Humulus scandens, Rosa chinensis, Eriobotrya laoshanica, and Hedera nepalensis var. sinensis, while Aml was partial to collect pollen of Ternstroemia gymnanthera, Chrysanthemum boreale, and Zinnia baageana.
Conclusions: In general, Acc and Aml can pollinate many kinds of plant during autumn and winter, and Acc have more extensive plant source. The investigation of pollination diversity and differences between Acc and Aml during the late autumn and winter periods will be helpful to study the pollination rules and preferences of honeybees, and provide theoretical for ecological protection in Hangzhou City.

Background & Aims: We reviewed progress on insect biodiversity research over the past 30 years and further analyzed the trends, focusing on varied study systems (e.g. forest, grassland and agriculture etc.) and important functional insect groups, such as pollinators, herbivores and predators.
Progresses: Declines of insect abundance and diversity are being reported worldwide. Anthropogenic disturbance, climate change, and other factors contribute to this crisis.
Strategies & Prospects: Studies of insect biodiversity have expanded from early comparisons of species richness on composition to multiple dimensions of diversity. Current studies include both in-depth work on morphological diversity and much deeper consideration of genetic, phylogenetic, and functional diversity. Moreover, the studies’ scale has expanded from local to global. The development of morphometrics and phylogenetic bioinformatics further contributes to understanding evolution and global patterns in diversity. We also need to pay more attention to topics on integrative taxonomy on functional insect groups, functional diversity, insect diversity within canopy, and species interaction networks.

Background: Research techniques in molecular biology, cell biology, microbiology and genetics have been accelerated by rapid development of modern genomic technologies. These advances have rapidly evolved the field of biodiversity research, once a branch of natural history focusing on morphology, into an integrated life science. Modern biodiversity studies can now investigate and link element of ecological systems, the species within them, and their genetic diversity. DNA related technologies, among other omics techniques, have continued to develop and launch new sequencing platforms, leading to a reduction of DNA sequencing costs that has already outstripped Moore’s Law, which also facilitates a series of breakthroughs in the research fields of biodiversity.
Prospects: Here, we introduce emerging trends in DNA-based omics techniques applied in biodiversity research, including species-level genomics as well as genetic diversity and community-levels species diversity. The former includes genomes obtained based on single individuals and genetic diversity of focal populations in both spatial and temporal dimensions, while the latter includes molecular identification approaches, such as metabarcoding, eDNA, iDNA etc. These new methods can be applied in biodiversity estimation for various communities, as well as in monitoring and conservation of flagship species and interspecific interactions.

Background & Aims: Alien plant invasion has significantly threatened native biodiversity, ecological security, socio-economic development, and human health. Consequently, exploring the mechanisms of alien plant invasion and its ecological impacts are of great importance to the ecologically sustainable development of our country. Both questions are also key topics in the field of invasion ecology. Over the past decade, ecologists have conducted much research and achieved fruitful outcomes, providing theoretical guidance for the prevention and management of invasive alien plants and biodiversity conservation.
Progresses: Based on domestic and international studies in this field over the past decade, the present article reviews the progress of plant invasion ecology, focusing on the following three aspects of the field. First, we present the roles of species characteristics, biotic and abiotic environments on alien plant invasion. Second, we review the impacts of alien plant invasion on native ecosystems. Third, we briefly introduce the term ‘native plant invasion’ as an analog to alien plant invasion, as well as applications of multi-omics technology in the area.
Prospects: The review looks ahead to further developments in invasion ecology, including that (1) multiple species experiments rather than single species experiments are more suited to obtaining gerneralizable findings; (2) the geographical scale is increasing, such as from local scale to latitudinal gradient pattern; (3) more studies are integrating multiple invasion theories, rather than one hypothesis, into a unified framework.

Aims: Diverse inflorescence forms, pollination strategies, and widespread deceptive pollination make the Araceae family a suitable research subject for plant-pollinator interactions and the effects of floral divergence. Elucidation of flower diversity and pollination strategy in Araceae by the previous studies enhanced our understanding in floral divergence making a firm foundation for this study. The present review aims to summarize the main types of inflorescence structure, spathe forms, pollination strategies, and their relationship in the plants of the family Araceae.

Progresses: There are four main types of spathes in Araceae: unmodified spathe, expanded planar spathe, erect broad spathe, and erect narrow spathe; demonstrating an evolutionary trend from simple planar structures to complex three- dimensional wrapped spathe structures. There are three types of spadix with the evolutionary route from bisexual flowering inflorescence to monoecious inflorescence, and to diecious inflorescence. The Araceae exhibits five major pollination strategies: food-rewards mutualistic pollination, odor-attracting deceptive pollination, mating sites mutualistic pollination, oviposition-attracting mutualistic pollination, and lethal trap deceptive pollination. The main types of pollinators include: Diptera, Coleoptera, and Hymenoptera. Plants in the Araceae family attract pollinators by their unique shapes, colors, stripes, heat of the inflorescences, and most importantly floral scent. We comprehensively discussed the function of volatile organic compounds, among the most important volatiles being dimethyl sulfide, methyl indole compounds, terpenoids and benzene compounds that attract coleopteran beetles and Diptera to pollinate by simulating food or brood-site signals.

Prospects: Further study on the evolutionary ecology and developmental biology of Araceae is expected to provide reasonable explanation for maintenance and evolution of deceptive plant-pollinator relationships. Studies should increasingly focus on exploring the pattern of volatiles variation in species differentiation and the physiological relationship between volatiles and pollinators. Uncovering the complex relationships between floral diversity and pollination strategy in this family will greatly improve our understanding in its floral divergence and expand our knowledge in evolution of flower diversity in angiosperms.

Background & Aims: Natural selection assumes that there is an expected fitness advantage (or aim) for any selection of gene mutations or phenotypic characteristics. However, the fitness of the selected gene mutation/phenotypic characteristic might vary as it spreads throughout a population or might vary with changing living environments over both evolutionary and ecological scales. This may result in a “paradox of stationary fitness landscape” in which an expected fitness advantage of a selected gene mutation/phenotypic characteristic might therefore not exist. Based on a dynamic state but not a stationary fitness landscape, we propose that natural selection might exhibit path-dependent selection.

Summary: In path-dependent selection, the gene mutation or phenotypic characteristics are produced completely at random, but some might meet a specific condition which could generate positive feedback as they spread. Such positive feedback might also be that such matched conditions could further facilitate the occurrence of a genetic trait/phenotypic characteristic. The positive feedback effect will therefore increase the probability of a genetic trait or phenotypic characteristic in specific conditions, meaning natural selection will depend on the probability of path, but not fitness value. Analogy to that many paths lead to a bus stop near your office building, the path-dependent selection argues that the quickest path might be mostly selected, especially when the bus stop is at a fixed location and selection pressure is strong. However, the other paths may also be selected especially when the bus stop could change location or selection pressure is weak. In path-dependent selection, both evolutionary history and distribution of ecological characteristics will greatly affect the evolution of any path. Using this understanding, different pathways can be understood as different points of speciation, where the distribution of species is similar to the peaks of a mountain in which the paths with a high probability will shape peaks, while many other species with low path probability will not separate into other peaks, creating sister species, cryptic species, or redundant species.

Prospects: Path-dependent selection can be described by the complex function, a mathematical skill widely used in modern physics. Through complex function, we can describe how multiple factors shape a probability of path-dependent selection in speciation peaks and the oscillation of species peaks. Different pathways, which could also be understood as different dimensional viewpoints, will demonstrate a different understanding of the evolutionary aim of a gene mutation, phenotypic characteristic.

Aim: The strategies of reproductive adaptation for alpine plants have long been a hot topic in evolutionary ecology, but there is still a lack of quantitative measures for reproductive traits under natural conditions. Here, we investigated reproductive adaptation of Rorippa elata, an endemic Brassicaceae species in one of the world's temperate biodiversity hotspots, the Hengduan Mountains (HDM).

Methods: We established a field-based common garden experiment at Shangri-La Alpine Botanical Garden in Yunnan. During 2019‒2020, we transplanted a total of 633 R. elata plants for 150 accessions across latitudes and performed manipulative field experiments. First, we collected several life history-related traits of R. elata, including germination rate, flowering time, over-winter survival rate, and pollination-relevant characteristics. We then carried out a set of four experimental treatments to characterize natural variation of the mating system in R. elata, including (1) strict selfing rate by bagging inflorescences before flowering; (2) common outcrossing rate by emasculation and open pollination; (3) strict outcrossing rate by emasculation and artificial pollination among accessions; and (4) natural reproductive rate under open pollination. For each treatment, we counted seed setting rate per fruit per accession and used this information to assign a mating system type for each R. elata accession. Furthermore, we also quantified the extents of pollen limitation and reproductive assurance.

Results: Our results showed that the main visitors of R. elata flowers were insects of Syrphidae, Halictus, Musca domestica, and Calliphoridae. Among these, insects of Syrphidae visited flowers most frequently and insects of Calliphoridae had the longest staying time per visiting. According to life history observations in the common garden, we demonstrated that R. elata plants germinated in early spring followed by a long period of reproductive growth throughout the synchronization of both high temperature and precipitation in HDM. They then entered into dormancy with living sprouts belowground during cold and dry winter. Correlation analysis of latitude with seed setting rate and over-winter survival rate showed that latitude was negatively correlated with the reproductive ability but positively correlated with the over-winter survival rate of R. elata. Comparative analysis of seed setting rates among experimental treatments found that R. elatapossessed a mixed mating system, with selfing dominant and intermediate types accounting for 45.5% and 39.4% of accessions, respectively. Furthermore, most R. elata accessions showed signs of reproductive assurance, but to different extents, with the highest in selfing dominant accessions (0.163) and the lowest in intermediate accessions (0.011).

Conclusions: Our findings reveal the reproductive strategies of R. elataat the population level and underscore a trade-off between reproduction and survival along a latitudinal gradient. The mixed mating system with variable reproductive assurance likely plays an important role in the stability of reproduction. Collectively, our results highlight the important contributions of reproductive strategies for alpine plants during their adaptation to mountain environments.

Background & Aims: Pollinators are declining worldwide and there is a global concern about how to conserve pollination services of agroforestry ecosystems. In theory, the pollination services are determined not only by the level of pollinator diversity but also by the adaptive capability of pollinator communities against disturbances. Recently, researchers have realized the importance of ecological resilience of pollination; nevertheless, the concept of ecological resilience of pollination is not clear and it is often misapplied to other ecological processes, like engineering resilience, resistance, and stability.
Objectives: This study explains the concept and content of ecological resilience of pollination and discusses the differences from other similar ecological processes. Moreover, the underlying mechanisms driving the ecological resilience of pollination are reviewed and the hypotheses explaining ecological resilience of pollination are summarized. The ecological importance of ecological resilience of pollination is addressed in terms of managing pollination functioning of agricultural ecosystems.
Progresses: Ecosystems under outer disturbances can absorb the disturbances by reorganizing the inner structures or components to let the ecosystem functioning remain unchanged or at an acceptable level. Reorganization of the pollinator communities under disturbances drives the occurrence of ecological resilience of pollination. Functional redundancy, density compensation, response diversity, interaction turnover, and cross-scale resilience are the five hypotheses explaining the ecological resilience of pollination, but they are often used imprecisely and incorrectly. We state that the five hypotheses are different but internally interlinked, explaining the ecological resilience of pollination at different spatial scales. From functional redundancy, density compensation, response diversity, interaction turnover to cross-scale resilience, the five hypotheses explain the ecological resilience of pollination ranging from small to large scales and from simple to complex ecosystems. Moreover, the hypothesis running at a relatively large spatial scale (e.g. cross-scale resilience) can be applied to explain the hypothesis at a relatively small scale (e.g. functional redundancy and density compensation). For each hypothesis, a conceptual diagram is presented to illustrate how pollinators reorganize their communities to enhance the ecological resilience of pollination. The experimental evidences to support the five hypotheses are still in shortage, particularly for interaction turnover hypothesis and the cross-scale resilience hypothesis. Nowadays, few studies have explored the pollination functioning of ecosystems by methods integrating the five hypotheses. Moreover, the relationships among the five hypotheses are not tested empirically by field study, either. Therefore, more field evidences are expected to support those hypotheses.
Perspectives: The ecological resilience of pollination is always measured using biodiversity indexes, such as species richness and Simpson diversity. Since ecological resilience of pollination is a measurement of ecosystem functioning, we suggest that its indictor need to integrate pollination functioning, such as pollen grains deposited on stigma surfaces, initial fruit sets and finial fruit sets. Future research also should examine how the disturbance intensification influences the ecological resilience of pollination and when the ecological resilience of pollination occurs. Moreover, the five hypotheses should be tested empirically and their relationships need to be explored. With the development of knowledge on ecological resilience of pollination, researchers can apply those theories to manage the agricultural ecosystems. For example, the ecological resilience of pollination can guide the researchers to determine when and how to provide the managed pollinators (e.g. honey bees) to safeguard the pollination functioning of ecosystems.

Aims: Arthropod biodiversity in farmlands has considerable value in terms of pest control, pollination, and other ecological services. To adequately assess arthropod biodiversity in farmlands, a fundamental step to select appropriate, accurate, and efficient sampling methods and identify appropriate indicator taxa.

Methods: Here, we compared several arthropod sampling methods in different types of agricultural habitats within organic managed and conventional managed farmland, including the surface trap cup method, coloured pan traps, the sweeping method, visual counting, and the vacuum-suction method. We compared the capture efficiency, economic costs, and response sensitivity of each method for different species assemblages.

Results: We found that the surface trap cup method and coloured pan traps had the highest capture efficiency, followed by the sweeping method, the vacuum-suction method, and visual counting, which had the lowest capture efficiency. Coloured pan traps was more efficient at capturing carabids, spiders, bees, and ladybugs. The surface trap cup method was mainly applicable to sampling ground spiders and carabids. The sweeping method was also effective at sampling spiders and ladybugs. In terms of economic costs, the most economical method was the surface trap cup method, which was used to capture carabids or spiders. The sweeping method had the highest cost due to its low capture efficiency of spiders. Sampling methods varied in their response sensitivity and were reasonably able to estimate abundances only of certain taxa (e.g., the number of spiders and carabids by the surface trap cup method, the total number of specimens, the number of bees, and the number of ladybugs by coloured pan traps, and the number of Orthoptera and Hemiptera by the sweeping method).

Conclusion: We further compared sampling methods after taking into account the economic value of the taxon, the difficulty of sampling operation, the difficulty of taxon identification, the degree of passive sampling, and whether the taxon was influenced by different individuals conducting the sampling. The most comprehensive method was the surface trap cup method targeting carabids and spiders. Using a combination of different sampling methods for multiple taxa is recommended to comprehensively evaluate and monitor overall farmland arthropod biodiversity, and our results suggest that the best combination includes sampling carabids and spiders using the surface trap cup method and sampling bees using coloured pan traps.

Aim: The impact of global climate change on ecosystems creates a pressing and significant challenge to society. Climate change is increasing the frequency and severity of extreme climate events, which have a direct impact on ecosystem productivity and service functions. Here, we conducted a literature review on research progress in this field, including analyses of interaction network structure, temporal and spatial distribution changes, and the importance of “rewiring” interactive relationships and functional traits.

Progress: Recent research has focused on the effects that increasing temperatures have on plant-pollinators in two primary ways. The first is the change in plant and pollinator distributions, including the potential for extirpation of some populations. The second is the change in plant and pollinator phenology, or the change in timing of plant flowering and pollinator activity. Spatial or temporal changes in plants and pollinators under climate change may cause mismatches and potential losses of current plant-pollinator relationships. In addition, climate change may alter the functional traits and coupling between plants and their pollinators, which could affect the stability of their interactions.

Outlook: We recommend that future research should increasingly focus on: (1) covering multiple scales of biodiversity, (2) long-term monitoring of plant-pollinator interaction networks, (3) measuring the fitness of important indicator species, (4) recording changes in the functional traits of plants and pollinators along spatial and temporal scales to help rewire and/or restore their interactions, and (5) evaluating the conservation status of key plants and their pollinators.

Aims: The adaptive significance of heterostyly is to improve the transfer of compatible pollen, so as to promote outcrossing. Nevertheless, many studies have found that a large number of incompatible pollens are deposited on the stigmas. At present, few studies have focused on whether the stigmas promote the compatible pollen germination and pollen tube elongation and provide evidences for the pollination accuracy hypothesis by emasculating intraflower and intraplant pollen.
Methods: Tirpitzia sinensis (Linaceae) was taken as materials, and the number of long-styled morph (L-morph) and short-styled morph (S-morph) of T. sinensis were investigated in the separate populations. The pollens and stigmas size of different morphs were measured and their surface ornamentations were observed. The viability of stigma and pollen of different flowering phases were measured. The percentage of different phenotypic pollens on the stigma were calculated. The percentage of compatible and incompatible pollens on the stigma were further calculated under intraflower, intraplant emasculation and natural control treatments. The pollen tube length and pollen germination rate of inter-morph, intra-morph and mixture pollination were measured. The heteromorphic self-incompatibility system was detected by artificial pollination treatments.
Results: There was no significant difference in the number of L-morph and S-morph of T. sinensis in the natural populations. The pollen volume of S-morph was significantly larger than that of L-morph, and the pollen surface ornamentations of the two morphs were different, but there were no significant different in the stigma surface areas and surface ornamentations of the two morphs. The pollen viability of the first flowering day was significantly higher than that of the second day, while the stigma viability had no significant difference in the first and second day of flowering. The percentage of incompatible pollen on stigma was significantly higher than that of compatible pollen in natural state. The intraflower and intraplant emasculation treatments significantly increased the percentage of compatible pollen deposition compared with the natural control in the L-morph of T. sinensis. Compared with inter-morph pollination treatment, the intra-morph pollination treatment could significantly reduce pollen germination rate and pollen tube length. Pollination treatments showed that T. sinensis was self- and intramorphic pollination incompatible.
Conclusions: These results indicate that the distyly improves pollination accuracy by promoting the compatible pollen germination and pollen tube elongation.

There are about 800 species of fig trees in the world, which are mainly distributed in tropics, some species extend to subtropics. Fig trees rely on agaonid fig wasps to pollinate and are also exploited by some non-pollinating fig wasps. Fig wasps depend heavily on temperature who can only maintain normal physiological functions within a certain temperature range that is more sensitive than fig trees. Temperature directly affects the fig wasp’s abundance and interspecific relationships. However, lack of research leaves a knowledge gap in our understanding of how fig wasp temperature tolerance affects the coexistence of wasps in fig. We conducted the experiment of temperature tolerance on six species of fig wasps from monecious Ficus altissima and F. racemosa, and dioecious F. semicordata in Xishuangbanna. Our results show that high temperature tolerance of all pollinating fig wasps was low, while the tolerance of Ceratosolen gravelyi on F. semicordata to low temperature was enhanced. When looking at fig wasp community composition on F. racemosa, the pollinating fig wasp are dominant species, but the population was decreased significantly in low temperature seasons in Xishuangbanna. While non-pollinating fig wasps showed the opposite pattern, which maintained high abundances during the cool-foggy season with low temperature due to greater temperature tolerances. On F. semicordata, non-pollinating fig wasps Sycoscapter trifemmensis had stronger temperature tolerance than Philotrypesis dunia so that the former had competitive advantage and large population. Differences in temperature tolerance of fig wasps plays an important role in species distribution, maintaining interspecific relationships and coexistence. Our results provide scientific evidence for understanding fig wasp coexistence.

Mistletoes are a polyphyletic group of hemi-parasitic shrubs that can conduct photosynthesis. As keystone resources, they provide important food resources and nest sites for many birds and other fauna in forests and woodlands, mediating local biodiversity. This group is comprised of 5 families, 88 genera and about 1,600 species within the Santalales and is broadly distributed across terrestrial ecosystems, absent only in some alpine, desert and polar areas. Research into the reproductive phenology of mistletoes is important for understanding the maintenance of species interaction networks in “host-mistletoe-pollinator/seed disperser” systems and the stability of ecosystem structure. We review the reproductive phenology of mistletoes at landscape, community, and population scales. We begin by describing different forms of mistletoe reproductive phenology, and continue by exploring the evolutionary and developmental drivers of host species, pollinator/seed disperser, and mistletoe biological characteristics. These studies indicate that long-lasting mutualisms between pollinators/seed dispersers and mistletoes are maintained mainly by asynchronous phenology of mistletoes in order to ensure their reproductive success. Previous studies found that the reproductive phenology of mistletoes had important adaptive significance to interacting species in “host-mistletoe-pollinator/seed disperser” systems. Future efforts should first prioritize basic biological research on mistletoes to fill important data gaps, and then couple experimental verification with comprehensive multi-factor analysis to strengthen our understanding of the ecological significance of mistletoe reproductive phenology.

Calanthe sieboldii is an orchid species with a narrow range of suitable habitats that are typically disjunction between continents and islands. Calanthe sieboldii relies on specific pollinators such as Xylocopa carpenter bees, including X. appendiculata, X. rufipes and X. chinensis. This study built a species distribution model (SDM) using the Biomod2 package of R to predict the distribution patterns of C. sieboldii and Xylocopa spp. in China under three different representative concentration pathways in 2050 and 2070. The results show the distribution of C. sieboldii is better explained by precipitation-related variables than temperature-related variables, 25.4% and 13.9%, respectively. The current suitable habitats for C. sieboldii are mainly in Central China and East China. However, future climate change scenarios may shift these habitats, which will shift to higher altitude area, and may change -59.0% to 34.7% dominated by future climate change scenarios. The range of suitable areas for Xylocopa spp. will decrease by 16.4%-19.7%, moving to Northwest and Northeast China. Consequently, as the co-distribution areas between plant and pollinators account for suitable areas C. sieboldii, the orchid’s distribution will decrease by 0.5%-11.4% from 90.0%, indicating that the distribution of C. sieboldii will suffer from future climate change and declining pollinators. Therefore, the pollinator should be considered carefully in the conservation of C. sieboldii or similar specialized-pollination orchid species.

Aims: The spatial distribution for plant species that rely on animal pollination for reproduction is influenced by the geographical distribution of their pollinators. Predicting the impact that future climate change will have on the geographical distribution of plants and their pollinators is significantly important for the conservation of biodiversity.

Methods: In this study, we conducted a field investigation to map out the distribution for three Astragalus species (A. camptodontus, A. pullus, andA. strictus) and their dominant pollinating bumblebees (Bombus). We collected 543 species distribution points for Astragalusand Bombusas well as 13 environmental factors from online database. Using the MaxEnt, we simulated suitable distribution changes for the three Astragalus species and two species of bumblebees (B. friseanusandB. rufofasciatus) under two climate change scenarios for 2100 (ssp245 and ssp585). We also combined with three possible migration situations into the models, i.e. full dispersal, no dispersal and only Bombus dispersal.

Results: We found that three Astragalusspecies are mainly pollinated by bumblebees and the most suitable distribution for Astragalus and Bombusis the Sino-Himalayas. It is predicted that by 2100, their suitable distribution will expand northwest, while distribution areas in the southeast will decrease. When the plant-pollinator interaction was included in the models, potential range size of the three Astragalusspecies was reduced by 15.83%-83.98%. Under low-emissions scenario (ssp245), the spatial match of three Astragalus species and their pollinating bumblebees is predicted to increase. However, under a high-emissions scenario (ssp585) the spatial match of A. camptodontus, A. pullusand their dominated pollinators B. friseanusis predicted to decrease. If species lack full dispersal ability or only Bombus disperse, the spatial match of A. strictusand its dominated pollinators B. rufofasciatusis predicted to decrease. Climate change and species dispersal ability may cause spatial mismatch between the Astragalusand their pollinating bumblebees. Our simulation shows that the environmental factors affecting the distribution of Astragalus and Bombus are different, but elevation is the most important factor.

Conclusion: Given the importance of pollinators for the life cycle of many plant species, our study could be used to better understand the potential effects of climate change on the spatial distribution of plants and their pollinators, particularly on species that with limited geographical range.

Fig and fig-pollinating wasps constitute one of the most well-known systems of mutualistic interactions between species. However, interspecific competition and antagonism is increasingly observed in this obligate mutualism system, including competition over common resources, pollination cheating and host sanction, and an evolutionary arms race between the host tree and its pollinators. In the competitive and antagonistic interactions between fig and fig-pollinating wasps, three main asymmetric relationships have been identified: (1) asymmetric payoffs, i.e., asymmetric power between figs (host) and their pollinators (symbionts); (2) asymmetric rates of evolution; and (3) asymmetric information between figs and their pollinators. The asymmetric relationships may affect population dynamics and the mutual adaptation and evolutionary strategies of each species, which helps explain why both cooperation and conflict are simultaneously observed within a specific mutualism, and why diversified strategies and species coexistence are found in nearly all mutualism systems.

Species form complex interactive networks within communities, which often experience seasonal species oscillations or species composition shifts. However, the variation that occurs within such networks is poorly understood. Studying seasonal changes of ecological networks may reveal the mechanisms that maintain the stability of a community. In this study, we collected fig wasps from Ficus benjamina during the dry and rainy seasons in Xishuangbanna to understand how fig wasp communities may shift seasonally. We compared fig wasp abundance, species composition, and metrics of coexistence networks (e.g. network diameter, connectance, nestedness, and community temperature) between the rainy season and the dry season. The pollinating wasp, Eupristina koningsbergeri was the most abundant species in both rainy season and dry season. There were more non-pollinating fig wasp species during the dry season (15 fig wasp species) than the rainy season (14 fig wasp species). A higher number of non-pollinating fig wasps can be detrimental to fig-pollinator wasp mutualisms because they reduce both fig seed production and pollinator abundance. Additionally, the dry season experiences higher species connectivity (0.95 in dry season, 0.47 in rainy season), higher network temperature (23.24 in dry season, 2.64 in rainy season) than the rainy season, which indicate more complex inter-specific interactions, and a higher level of disturbance of fig wasp community in the dry season.

It has been widely accepted that pollinator-mediated selection is responsible for the evolution of flower traits. To date, two distinct methods of phenotypic manipulation and phenotypic selection analyses have been used to demonstrate flower function and potential selection. However, empirical studies combining both methods are rare in wild plants. Through manipulating sepal size of Delphinium kamaonense var. glabrescens (Ranunculaceae) and performing phenotypic selection analysis, this study examined functions of two flower traits and the potential selection on them. Sepals manipulated to be smaller significantly decreased visitation rate of pollinators, but did not affect seed number per flower or seed set. Sepal size mainly affected pollen export mediated by pollinator attraction rather seed production. Phenotypic selection estimated through female fitness showed no significant gradient with varying sepal width and length. However, significant linear selection differential and selection gradient on the spur length were observed, showing higher seed production in individuals with longer floral spurs. This study suggests different function and potential fitness consequences of floral traits that were subject to natural selection.

Hybridization plays a vitally important role in biological evolution and speciation. Although occurring frequently in nature, the prevalence of hybridization events is unevenly distributed across the plants. It is generally considered unlikely for the obligate insect-pollinated plants, due to the much stronger prezygotic barriers which were developed during their long co-evolutionary with the host-specific pollinators, such as the fig-fig-pollinating wasp mutualism. Species-specificity in fig pollination appears to be extreme compared with most other insect pollination mutualisms. Most fig species are pollinated by only one wasp species and most wasps are associated with just a single fig species. However, increasing cases of host shift have been reported with the deepening of research, which raises the research and discussion on hybridization between host fig species. Here, the research progress on the interspecific hybridization in Ficus is presented from the following five aspects, artificial hybridization, hybridization between exotic and native species, natural hybridization of island species, natural hybridization of sympatric allied species, and hypothesized hybridization by phylogenetic incongruence. Some further research prospects on the Ficus interbreeding are also outlined. Artificial F₁ hybrids between the closely related species of the same subgenus are usually fertile. However, intensity difference of cross-fertilize compatibility between species of different subgenera exists between the different breeding systems. There is unidirectional or bidirectional but asymmetrical interspecific gene flow. Introgression may be the most prominently and prevalently hybridization process in Ficus because of the extreme dependence on pollinating fig wasps for sexual reproduction. A series of prezygotic isolation mechanisms maintain the genetic and morphological identity of fig species, including chemical, mechanical, geographic, temporal and ecological isolation. However, the postzygotic isolation is weak effective. The reproductive fitness of pollinating fig wasp is reduced obviously in atypical host species. Future research work needs to be carried out in investigating the effect of hybridization on fig biodiversity and the stability of the fig-fig-pollinating wasp mutualism, and exploring hybridization pattern and consequence of the hybrid zone, and the factors that affect the host shift and hybridization, and so on.

Plants that have a dimorphic mixed-mating system consisting of open chasmogamous flowers (CH) and closed cleistogamous flowers (CL) have special reproductive strategies. Further research on CH-CL mating systems can help us understand the maintenance mechanism, evolutionary trends and strategies of plants in response to environmental change. This paper reviews existing literatures on dimorphic flowers (dimorphic mixed-mating system) of CH-CL systems including the effects of different abiotic and biological factors on the growth, development and relative proportion of flowers. It also reviews the maintenance mechanisms and evolutionary significance of dimorphic flowers. Recent researches of CH-CL system and remaining scientific questions are outlined and the new understanding of CH-CL systems based on recent research is reviewed. We suggests that it is necessary to accurately detect the differences between the progeny of the two flower forms in heterogeneous habitats and at different stages of life history. The microenvironment (separation pattern and location effect of seeds) is also identified as being very important for seed germination and the growth and development of the two flower types. Additionally, the expression mechanism of the spatial and temporal differences in flower types (the pattern of flowering and sensitivity to heterogeneous habitats) may be related to changes at the levels of endogenous hormones. It has been said that the distribution of populations of different natures and different sources, and the impact on the genetic structure, is likely to be an important mechanism for the maintenance of the system. Therefore, in-depth research and scientific understanding of dimorphic mixed-mating system may be of great significance for understanding the evolution of the entire plant reproductive system.

Bombax ceiba is a tall tree species with predominantly red flowers and is normally pollinated by birds. In some populations, a yellow flowered variety occurs. Honeybees frequently visit these uncommon yellow flowers but how this adaptation affects the life history of this variant remains unexplored. In the present study, floral syndrome and pollination mechanism of yellow flowers were compared with red flowers of B. ceiba populations on Hainan Island, southern China. The results showed that main nectar components of two floral phenotypes are both glucose and fructose dominated, and the volatile chemicals are mainly alkanes, esters, phenols and acids with no significant difference between the two phenotypes. The relative spectral reflectance showed that both birds and honeybees could detect the yellow flowers, suggesting visitation by honeybees can compensate for times when bird visitation is low. Compared with red flowers, yellow flower had a lower degree of dichogamy, which might increase selfing possibilities and provide reproduction assurance when red flowers receive low bird visitation. Interestingly, yellow flowers had a relatively higher degree of herkogamy, i.e. stigmas are much higher than anthers when compared to the red flowers. Greater herkogamy in yellow flowers may reflect an adaptation to decreased dichogamy, avoiding autonomous selfing and interference between female and male organs. Fruit set of the yellow phenotype (1.08 ± 0.56)% was lower than that of red phenotype (3.27 ± 0.93)%, suggesting pollen-limitation in B. ceiba. We propose that yellow flowers, with greater herkogamy but lower dichogamy, promote pollination via attracting diverse pollinators and protect red flowers from disturbance of honeybees.

To provide a reference for researchers, achievements and progress in recent years on the fertility of Rhododendron in China and abroad were summarized. (1) There are polyploidy in subgen. Rhododendron and subgen. Pentanthera, and even various ploidy in the same species. (2) Under natural pollination, in addition to the common intra-specific cross- and self-fertilization, inter-specific cross-fertilization was also widespread in subgen. Hymenanthes, subgen. Rhododendron and subgen. Tsutsusi. There were also some cases of inter-subsection cross. (3) Self compatibility (SC) and self incompatibility (SI) simultaneous exist in Rhododendron. Subsect. Fortunea shows all types from self sterile to high fertility. Self incompatibility often occurs in subgen. Tsutsusi and subgen. Azaleastrum and although self-fertilization is usually considered to be a passive adaptation, it could be an active response to the adverse environmental conditions for a few local species. (4) Through artificial crosses between different taxa (subgenera, sections and subsections), the inter-specific crossability was obviously relevant to the relationship of phylogenetic development and chromosomal ploidy of parents. This was reflected in the changes of indices of compatibility in different phases of development and was discovered that hybridization was easier between distant subgen. Hymenanthes and subgen. Rhododendron. There were also some cases of compatibility such as the reciprocal crosses between subgen. Hymenanthes and subgen. Tsutsusi, subgen. Tsutsusi and subgen. Rhododendron as well as the unidirectional compatibility between subgen. Tsutsusi and subgen. Pentanthera, subgen. Hymenanthes and subgen. Pentanthera, subgen. Azaleastrum and subgen. Rhododendron. (5) It leads to increases in the fertility and development from bidirectional fertility to unidirectional sterility and then bidirectional sterility in inter-specific cross as SI parents get involved.

Invasive plants that use local pollinators would better ensure their expansion in the new environment, but the role and status of the invasive plants on local pollination network is still unclear. In this paper, we analyzed the pollen grains of Tagetes minuta carried by pollinators and constructed a plant-pollinator network, to explore the roles and impacts of T. minuta in local pollination network. The results showed that pollination system of T. minuta was generalized, and there were 13 insect species visiting its flowers, 12 of which carried pollen grains of T. minuta, and the pollen grains of T. minuta accounted for 89.89%. Among the 12 pollinator species of T. minuta, one species of bees, two species of scorpion flies and one species of flies are the main pollinators. This study reveals that T. minuta has successfully used a variety of local pollinators for pollination in a relatively short period of time, indicating that T. minuta has strong adaptability and diffusion ability, and it is necessary to pay more attentions to the prevention and control of T. minuta in the future.

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, homostylous annual herb; the former depends on insect pollination for seed production. Thirty species have been named in the genus Fagopyrum (Polygonaceae) in the world. Investigations of morphology and genetic diversity suggest that Southwest China is the diversity center of Fagopyrum, especially in the area of Three Parallel Rivers, the upper Yangtze River Valley, where ancestral species of the two buckwheat crops were originated. Previous studies of basic biology on the buckwheat crops are briefly summarized here. Future studies of the taxonomical revision on the genus Fagopyrum, collections of wild germplasm resources, exploration of the interspecific relationships and the breeding of cultivars with superior agronomic traits are strongly needed. Palynological and archaeological evidences imply that the buckwheat crop has been cultivated at least 4,500 years in the Yangtze River Valley, and might have ever been a main food for local populations in the mountain areas, providing food resource for emerging of Yangtze River civilization. Deep understanding of the basic biology of buckwheat with modern techniques of genomics could clarify the origin of cultivated buckwheat and factors limiting seed production. The buckwheat could be a superior crop in the mountain areas if the traits with high agronomic and medicinal value can be excavated and exploited.

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 fragmentation, and global climate change have increased the risk of pollinator decline and extinction, which would have detrimental effects on ecological function and agricultural production. To maintain the stability of ecological interactions between plants and pollinators, a series of pollinator monitoring schemes have been established, ranging from the regional to international scale. Participants including volunteer citizens and professional scientists have obtained the status and trends of pollination systems, thereby helping to provide early alerts and feedbacks for the risk of natural and agricultural ecological systems. In this view examining the methodologies of pollinator monitoring, we emphasize that it is necessary to distinguish pollinators from floral visitors. A diversity of direct and indirect methods for monitoring pollinators is summarized for seven types of animals (including Lepidoptera, Coleoptera, Hymenoptera, Diptera, Aves, Mammalia, and Lacertilia, respectively). A simple monitoring program that includes volunteer participation is also recommended. Commonly used field monitoring strategies for seven groups of pollinators would be useful as references for monitoring additional pollinator faunas. The pros and cons of these diverse methods for protecting and monitoring pollinators are discussed, which is useful for the long-term detection of pollinator dynamics.

Pollinators serve key ecological functions, ensuring stable ecosystems and high agricultural yields. Hence, assessing ecosystem health and effects of agricultural management would benefit from understanding and monitoring pollination networks, which involves identifications of pollinators and pollinated plants. Classic approaches of morphology-based identification of plants and pollinators can be time-consuming, labor-intensive and costly, and require highly specialized taxonomic expertise. In comparison, DNA barcoding and high-throughput sequencing technologies can provide efficient and accurate identifications of plants and their pollinators, which may facilitate construction of pollination networks. Here we propose using sequencing technologies with a PCR-free genome-skimming work frame, using "super DNA barcode" as a new method to assess plant-pollinator networks. We expect this technique to improve resolution and accuracy of taxonomic identification to help gain quantitative information for bulk samples of pollinators or pollens. Although there are technical challenges to be resolved, the robustness of the new methodology has been validated in relevant biodiversity studies, suggesting promise in constructing pollination networks.

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 possess following reproductive traits: hermaphrodite-dominated sexual system, autonomous selfing-dominated breeding system, even asexual reproduction and apomixis, and high proportion of resources allocated to sexual reproduction, which may facilitate the success of some invasive plants. In turn, non-native plants could alter native plant-pollinator interactions, and in most cases decrease pollinator visitation and fitness of native plants. In addition, non-native plants may act as environmental stresses triggering rapid adaptation and evolution in reproductive strategies and phenotypes of resident native species in receipt communities. Studies in this field mostly have focused on rapid adaptation of invasive species to their new environments, while how native and non-native plants co-adapt and diverge remains largely unexplored, in particular from the perspective of plant reproduction. A better understanding of competition and cooperation between native and non-native plants will shed lights on rapid responses of native plants to non-native plant invasions. Such community studies of interspecific interactions with or without a competitor could provide evidence for displacement of reproductive traits and species coexistence, and improve our ability to predict and manage non-native invasive plants.

Clonal plants reproduce asexually via clonal growth and simultaneously reproduce sexually, and the consequences of clonal growth on pollination and mating have been one of the essential questions in ecology and evolution of plant reproduction. An increasing number of studies report the effects of clonal size, architecture, genetic diversity, and floral deployments on pollinator visit and behavior. The most common view is that clonal growth produces large floral displays and therefore increases attraction to pollinators. Consequently, clonal growth may help to maximize male reproductive success by dispersing more pollen. On the other hand, geitonogamy, pollination among flowers within one individual plant, is an inevitable byproduct with an increase in clone size. More frequent geitonogamous pollination has been expected in clonal plants with large floral displays and leads to a reduction in female fitness because of inbreeding depression or pollen clogging. However, some recent theoretical and empirical studies suggest new ideas on this issue. First, the number of flowers visited by individual pollinator within a clone did not increase proportionally with clone size in clumped clonal plants, and pollinator movements within a single bout mainly occurred within ramet. The selfing component analyses based on molecular markers further evidenced that within-ramet geitonogamy was the largest contributing factor to the total geitonogamy in two clonal species. Second, the experimental study of bumblebees foraging on artificial flowers showed that when the same amount of flowers was distributed among multiple ramets, geitonogamy was not higher but in fact, lower compared with one single inflorescence. The model-based simulation suggested clonal growth could promote pollination quality without increasing geitonogamy when flowers simultaneously received and donated pollen. These studies support a novel explanation of the evolution of clonality in plants. Future studies on the pollination ecology of clonal plants may focus on the effects of clonal growth on pollinator behavior and plant mating from multiple angles. Comparative studies between clonal and non-clonal taxa or between clonal and non-clonal populations of the same species are required to evaluate the ecological and evolutionary consequences of clonal growth.

Insect pollinators play a vital role in plant sexual reproduction. Pollinators facilitate cross-pollination that in turn promotes genetic diversity, mediates plant speciation, and contributes to ecosystem stability. However, the abundance, diversity and health of wild pollinators are threatened by human activities such as anthropogenic climate impacts, habitat destruction and environmental pollutants, and the impact of these human activities on ecosystems is likely to increase. Despite recognizing the importance of wild pollinators and the implementation of targeted conservation programs, the contemporary threats of wild insect pollinators remain poorly understood. For the giant honey bee (Apis dorsata), an important wild pollinator and honey producer in tropical rainforests and agricultural areas across Asia, here we describe nest characteristics, colony migration and pollination role and review threats to their conservation. We found that A. dorsata nests featured a single honeycomb hanging from the branches of large trees. The bees undertook long distance migrations to locate seasonally ephemeral forage sources but regularly returned to previous nesting sites. We identified several anthropogenic activities that posed significant threats to A. dorsata conservation: harvesting entire colonies, deforestation, pesticide and herbicide utilization, parastioids, mites, pathogens and climate change. Based on our study, we recommend several conservation initiatives to promote wild A. dorsata populations, which include artificial domestication, developing ecological agriculture, establishing of ecological corridors, inspection and quarantine controls on domesticated colonies, and sustainable utilization of the floral resources used by A. dorsata. We hope that this review will stimulate future research on giant honey bees whilst playing a significant role in their conservation and sustainable utilization.

Bumblebees are important pollinators of many wild flowers and crops and play a significant role in maintaining natural and agricultural ecosystems. The varied geomorphology and vegetation of China makes it the greatest hotspot of bumblebee diversity in the world. However, the bumblebee fauna of China has been insufficiently studied. Here, we report the results of systematic field surveys and the application of bumblebees to pollination over the last two decades in China. The results showed the following: (1) More than 50,000 bumblebee specimens were collected during 2002-2017. The taxonomic status of some difficult taxa was revealed by integrating morphology with DNA barcoding. A total of 125 bumblebee species have been identified, which represents 50% of the total number of bumblebee species worldwide. (2) We report the first compiled list of the bumblebee species of China, which includes 22 species that are endemic to China. The transitional zone from the eastern Qinghai-Tibetan Plateau to the Loess Plateau, the Qinling Mountains, and the Sichuan Basin is the centre of bumblebee diversity worldwide. (3) Six native bumblebee species, including Bombus lucorum, B. patagiatus, B. ignitus, B. pyrosoma, B. picipes and B. lantschouensis from Northern China, were selected for rearing between 1998-2017. Furthermore, B. patagiatus and B. lantschouensis, which had traits that favoured domestication, are now used as pollinators of crops in greenhouses within China. We propose a multi-pronged strategy to conserve the native bumblebees of China, which includes protecting their habitats and food resources and controlling invasive alien species and pesticide use. We hope that this study will help inform the conservation and the sustainable use of wild pollinators across the globe, but especially bumblebees of China.

Heteracia szovitsii (Asteraceae) is a common ephemeral annual species occurring only in desert regions of northern Xinjiang in China, with short-lived florets and achenes within a single infructescence (capitulum) having three different morphs. To explore the relationship between morphological differences in florets and the polymorphic fruits and reproductive characteristics, we compared floral traits, flowering pattern, and flower visitors to the three floral morphs in H. szovitsii, and reproductive efforts by hand pollination treatments. The results showed that: Peripheral and intermediate florets did not have pappus, while central florets did. Number of florets and length and width of ligules were significantly different among the three floral morphs in a single capitulum. Further, the length of stigma lobes of peripheral florets was significantly greater than that of central florets, the length of ovary beaks of central florets was significantly greater than that of peripheral and intermediate florets. Differences in morphology with or without pappus, width of ovaries, length of ovary beaks among three morphs of florets were consistent with those of three morphs of achenes. These results indicated that the numbers of three morphs of achenes and their morphology had differentiated during the development period of three kinds of florets. The concentrated flowering pattern of blooming in the morning of three kinds of florets within capitulum, made the capitulum act as functional units, i.e. like a flower, thereby increasing flower display and attracting pollinators. Pollinator visits may facilitate outcrossing during the short flower longevity. Pollen grains of the three floral morphs could germinate and produce pollen tubes on their stigma lobes, indicating that this species is self-compatible. The three kinds of florets bagged without emasculation all can produce achenes, but fruit-set was all significantly lower than that of natural pollination, suggesting that this species could be autogamous and cross-pollination could increase fruit set. Due to the protandrous and the pump/bush mechanism of secondary pollen presentation, pollen of three floral morphs was present at the apex of the stigma and on the brush of hairs of both the upper part of style and outside lateral of the closed stigma lobes. This character prolonged the duration of pollen presentation (male stage), and reduced the interference between male and female functions within flower, promoted cross pollination, thereby improving male/female fitness. Meanwhile, it could allow the pollen deposition on the lobes when the stigma lobes expanded to complete self-pollination autonomously. Halictus sexnotatulus was the most frequent floral visitor, and the duration time among insects visiting, inflorescence opening, highest pollen viability and the highest stigma receptivity had a high degree of synchronicity. This strategy facilitated the output of pollen at the male stage and receipt of pollen on the stigma at the female stage, thus ensuring that pollination was completed quickly and effectively in a short time after flowering and that outcrossing was successful. In the desert spring environment of the northern Xinjiang, H. szovitsii with short-lived florets can not only provide reproductive assurance via autonomous self-pollination quickly under the condition of the lack of pollinators and/or limited activity due to low temperatures and windy conditions, but also can provide the opportunities for outcrossing, through concentrated flowering, protandry and secondary pollen presentation when environmental conditions became favorable for pollinator activities.

Floral longevity, the length of time that a flower remains open and functional, varies greatly among species. The high plasticity of floral longevity can reflect an adaptation to variable pollination environments. In the alpine meadows of Qinghai-Tibetan Plateau (2,900 m vs. 3,600 m), we assessed how potential floral longevity, the shortest floral longevity and the actual floral longevity of 11 species varied under treatments of different pollination contexts. We modeled the response of floral longevity to pollinator exclusion (potential floral longevity minus actual floral longevity) and supplemental pollination (actual longevity minus shortest longevity), and the plasticity of floral longevity (potential longevity minus shortest longevity) at high and low altitude habitats. We found that the plants at the high-altitude community had longer potential floral longevity compared to the low-altitude community, while the shortest floral longevity was not significantly different. Furthermore, pollinator exclusion significantly increased flower longevity, while supplemental pollination significantly decreased floral longevity (i.e. the potential floral longevity > the actual floral longevity > the shortest floral longevity) in both high and low-altitude habitats. In comparison with the low-altitude community, high-altitude plants exhibited higher plasticity of floral longevity. Overall, our results suggest that greater plasticity of floral longevity may increase the opportunity for pollination and thus aid fitness at higher altitudes where pollinators are scarce and unpredictable.

As a comprehensive and interdisciplinary platform on biodiversity assessments, it is foreseeable that the assessment reports and policy recommendations of Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) will exert key effects on global biodiversity conservation. Based on the analysis of the pollinators protection policy formulation and implementation process in USA, this research gained the process and mode on establishment of the biological diversity related protection policy, scientific evaluation-government attention-the introduction of restrictive policies and measures. Considering the first thematic assessment report delivered in 2016 by IPBES, The Assessment Report on Pollinators, Pollination and Food Production, we speculated that the deliverable may facilitate a restrictive policy on the new neonicotinoid pesticide industry and bee products trade, especially wild bee products. We further analyze possible impact of IPBES deliverables on biodiversity and related protection policy in the world and China, in terms of promoting scientific research and evaluation on biodiversity and ecosystem service, mainstreaming biodiversity conservation and bring it to be an important political issue and so on. In addition, our research will provide support for establishing adaptation policies for biodiversity conservation in China.

Wild pollinator bees play an important role in ecosystem function and food security. In recent years, natural forests have been lost, while afforestation programs are primarily monoculture plantation, whether commercial or restorative. The net effect for bees has been fragmentation and sometime wholesale loss of habitats. For instance, diversity of wild bees in pure forest, Camellia oleifera and rubber (Hevea brasiliensis) plantation was found to be unexpectedly low. The rampant use of neonicotinoid pesticides and herbicide is known to negatively impact development and behavior of bees. Urbanization has dramatically impacted bee communities, with significant changes in species richness between suburban and central business areas. These are likely tied to the effect of effluent, exhaust gas and dust on foraging, growth and development. Climate change from greenhouse gas emissions can disrupt the mutualistic relationship between pollinating bees and plants via rapid phenological shifts. The above environmental changes occurring in China are likely cause wide declines in diversity and decreases in populations. Although China has rich natural heritage for bees, there is a lack of long term monitoring programs for species of pollinator bees and a dearth of data on distributions of bee species. As a result, the drivers of bee community composition and population decline are poorly understood. We emphasize the need to prioritize surveys of pollinating bees, continue ongoing monitoring programs and build wider research networks for the study of wild pollinator bees. These steps will ensure that sufficient data can accumulate for developing a prediction and risk assessment framework to help manage the declines in pollinating bee populations and mitigate the attendant economic and non-economic impacts.

The fig-fig-pollinating wasp symbiosis provides a model system for investigating the mutualistic interaction between plants and animals. A simple one-to-one rule was proposed to describe the highly specialized reciprocal relationships between figs and their species-specific pollinating fig wasps based on the initial studies: each fig tree species is obligatorily pollinated by one fig wasp species, and each wasp species can only reproduce in one fig species. With the deepening of research, however, increasing cases of breakdown in species-specificity have been reported, especially the reveal of cryptic pollinating fig wasp species progressively weaken the universality of one-to-one rule in fig-fig-pollinating wasp symbiosis. The documented cases of breakdown in the one-to-one rule were divided into two types, including copollinator and pollinator sharing, which have their own different mechanisms. Pollinator sharing is pollination of different species of Ficus by the same pollinator, while copollinator is the co-occurrence of more than one species of pollinators in one host fig. Here, the research progress on the breakdown of one-to-one rule is presented in three stages, i.e. morphological description, multidisciplinary evidence and discovery of cryptic pollinating wasp species. Some future challenges and research prospects resulted from the breakdown of one-to-one rule are outlined. Copollinators may lead to the interspecific hybridization between pollinator species, while pollinator sharing may result in the hybridization of host figs. Nonetheless, the hybridization in fig-fig-pollinating wasp symbiosis is very rare and suggests a strong level of reproductive isolation. Furthermore, the incidence and pattern of pollinator sharing and copollinator are differentiated in dioecious and monoecious figs, which suggests a differentiated host-specificity. The identification of cryptic species triggers the research of its speciation and co-occurrence, as well as the reassessment of pollinator biodiversity. Failing to recognize cryptic species also will limits the effectiveness of the controlled experiment in fig-fig-pollinating wasp symbosis. Each pair of fig and pollinating wasp possesses its distinctive coevolutionary history, and there are more than 750 pairs across the globe, which provide rich materials to explore the coevolutionary process and mechanism between plants and animals. The integrated study of formation, maintenance and breakdown mechanisms of the host-specificity will contribute to the understanding of fig-fig-pollinating wasp mutualism, and the coevolutionary process and mechanism between plants and animals.

The discontinuous distribution between alkaline limestone soil with high calcium content and acidic red soil with low calcium content is characteristic of karst areas, and strongly affects plant species composition in natural communities. Whether the soil types affect plant reproductive success, however, remains unknown. Two populations of Corydalis sheareri, a species commonly occurring in alkaline limestone soil and acidic red soil, were investigated. The soil properties of the two habitats were examined, and flowering phenology, floral traits, floral visitor types and their behavior, breeding system and reproductive success were compared. Organic matter, total nitrogen, total calcium, and pH value were higher in the limestone soil, while soil moisture content was lower than that found in the red soil. Floral longevity was not significantly different between plants from the two habitats. However, plants found in the limestone soil were shorter in height and bloomed one week later with a shorter flowering period (4 weeks) than those found in the red soil (6 weeks). Floral traits (inflorescence size, flower length, opening size, spur length and stigma diameter) were not significantly different between the two habitats. Corydalis sheareri was obligately xenogamous, with sexual reproduction dependent on insect pollinators. The major floral visitor was Anthophora melanognatha, a long-tongued nectar collecting bee. Bee visit frequency and seed set per flower were not significantly different between the two habitats, but fruit set per plant in the limestone soil was significantly lower. Our results indicated that, no difference in the seed set could be explained by similar pollinator abundance, while the differences of flowering phenology and fruit set could be caused by differences in the soil properties between the two habitats.

The transfer of pollen in most seed plants relies on diverse pollination vectors. In comparison with animal pollination (zoophily), wind pollination (anemophily) has long been regarded as an inefficient mode and thus has received relatively little attention. However, the majority of gymnosperm species and over 10% of angiosperm species are wind pollinated, and the evolution of wind pollination from insect-pollinated ancestors has occurred at least 65 times in angiosperms. Furthermore, ambophily, a combination of wind and insect pollination, is also reported frequently. More refined methods are thus seriously needed to explore the existence and mechanisms of wind pollination in diverse ecosystems. In this paper, we explore the scope of anemophily research by describing the species and habitat diversities of wind-pollinated plants. In field experiments, we recommend using pollen traps (sticky slides or airborne particle samplers) to quantify airborne pollen, and conducting pollinator exclusion, bagging, and emasculation treatments to explore the reproductive contribution of anemophily and the possibilities of zoophily, autogamy, and apomixis. In constrained field conditions, researchers can bring relevant plant tissues back to the laboratory for experiments examining aerodynamics, i.e., measuring the settling velocity of pollen using stroboscopic photography or drop towers, calculating the pollination efficiency using wind tunnels, and evaluating the aerodynamics based on computer models in different simulated conditions. Furthermore, the abiotic and biotic factors (wind pollination syndromes) associated with anemophily should also be studied to explore the causes as well as the ecological and evolutionary consequences of wind pollination. The above methods cannot substitute for one another, as researchers should use them as a comprehensive unit when possible to reveal the details and mechanisms of wind pollination.