Autonomous Selfing Research Articles

Pollen limitation influences the divergences in mating system and floral traits between two sympatric Halenia species

Abstract The mating systems and floral traits often among relatives of hermaphroditic plants can exhibit considerable diversity. This diversity can be influenced by the evolution of selfing and associated floral traits as a form of reproductive assurance when pollen limitation results from insufficient pollinator availability. To explore whether the degree of pollen limitation primarily drives differences in mating systems and floral traits, we conducted a comprehensive study involving two closely related species, Halenia elliptica and H. grandiflora, in three sympatric sites. We investigated floral characteristics, pollinator visitation, pollen limitation, autonomous selfing ability, reproductive assurance and mating system in studied populations. Our findings show that H. elliptica produces smaller flowers and less nectar production than H. grandiflora, making it less attractive to pollinators. Compared with H. grandiflora, H. elliptica experienced more severe outcross pollen limitation, but compensates with a higher capacity for autonomous selfing, ensuring seed production under natural conditions. Moreover, significant differences in mating systems were detected between them, with H. elliptica exhibiting a higher selfing rate than H. grandiflora across all studied sympatric populations. These differences are also reflected in variations in herkogamy and dichogamy. Our study suggested that the degree of outcross pollen limitation impacts the divergence in mating systems and floral traits between sympatric closely related species, offering valuable insights into the evolution of plant mating systems and floral traits.

Cover Image

Left: Natural habitat of the wild cotton Gossypium turneri in the coast of San Carlos, Sonora, Mexico. Right: Flower of Gossypium turneri in San Carlos, Sonora, Mexico. Flowering follows the rainy season in Sonora and the flowers are hermaphrodite with yellow petals and red spots near the base.Photos by Karla Fabiola Yescas‐Romo. Photos are courtesy of the authors of the article: Yescas‐Romo, K. F., Hayano‐Kanashiro, C., & Molina‐Freaner, F. (2024). Pollination biology of Gossypium turneri: Autonomous selfing provides reproductive assurance in an endangered wild cotton from Sonora, Mexico. Plant Species Biology, 39(5), 260–274. https://doi.org/10.1111/1442-1984.12474image

Do flower-colonizing microbes influence floral evolution? A test with fast-cycling Brassica.

Pollinators are thought to be the main drivers of floral evolution. Flowers are also colonized by abundant communities of microbes that can affect the interaction between plants and their pollinators. Very little is known, however, about how flower-colonizing microbes influence floral evolution. Here we performed a 6-generation experimental evolution study using fast-cycling Brassica rapa, in which we factorially manipulated the presence of pollinators and flower microbes to determine how pollinators and microbes interact in driving floral evolution. We measured the evolution of 6 morphological traits, as well as the plant mating system and flower attractiveness. Only one of the 6 traits (flower number) evolved in response to pollinators, while microbes did not drive the evolution of any trait, nor did they interact with pollinators in driving the evolution of morphological traits. Moreover, we did not find evidence that pollinators or microbes affected the evolution of flower attractiveness to pollinators. However, we found an interactive effect of pollinators and microbes on the evolution of autonomous selfing, a trait that is expected to evolve in response to pollinator limitations. Overall, we found only weak evidence that microbes mediate floral evolution. However, our ability to detect an interactive effect of pollinators and microbes might have been limited by weak pollinator-mediated selection in our experimental setting. Our results contrast with previous (similar) experimental evolution studies, highlighting the susceptibility of such experiments to drift and to experimental artefacts.

Strong habitat and seasonal phenology effects on the evolution of self-compatibility, clonality and pollinator shifts in Lachenalia (Asparagaceae: Scilloideae).

Plants employ a diversity of reproductive safeguarding strategies to circumvent the challenge of pollen limitation. Focusing on southern African Lachenalia (Asparagaceae: Scilloideae), we test the hypothesis that the evolution of reproductive safeguarding traits (self-compatibility, autonomous selfing, bird pollination and clonal propagation) is favoured in species occupying conditions of low insect abundance imposed by critically infertile fynbos heathland vegetation and by flowering outside the austral spring insect abundance peak. We trace the evolution of these traits and selective regimes on a dated, multi-locus phylogeny of Lachenalia and assess their evolutionary associations using ordinary and phylogenetic regression. Ancestral state reconstructions identify an association with non-fynbos vegetation and spring flowering as ancestral in Lachenalia, the transition to fynbos vegetation and non-spring flowering taking place multiple times. They also show that self-compatibility, autofertility, bird pollination and production of multiple clonal offsets have evolved repeatedly. Regression models suggest that bird pollination and self-compatibility are selected for in fynbos and in non-spring flowering lineages, with autofertility being positively associated with non-spring flowering. These patterns support the interpretation of these traits as reproductive safeguarding adaptations under reduced insect pollinator abundance. We find no evidence to support the interpretation of clonal propagation as a reproductive safeguarding strategy.

Mating strategies of Vitex negundo L. var. heterophylla (Franch.) Rehder (Lamiaceae): A mixed mating system with inbreeding depression.

Plant reproductive ecology is one of the research hotspots in ecology. With the increasing attention paid to the conservation of plant diversity, the research on reproductive characteristics and flowering biological characteristics of more species has attracted more attention. However, plant reproduction is affected by multiple interacting factors such as pollen limitation and resource availability. Vitex negundo var. heterophylla (Franch.) Rehder (Lamiaceae) is a significant species for water and soil conservation. Previous studies have revealed its mating system by the biological characteristics of flowering and SSR markers, but its reproductive strategies remain to be further studied. We evaluated reproductive success through artificial pollination to explore the reproductive characteristics of V. negundo var. heterophylla for the first time. From the results of fruit set, there is a mixed mating system dominated by outcrossing in V. negundo var. heterophylla accompanied by self-compatibility, and it cannot carry out autonomous selfing. Our data show the pollinator-mediated interaction in the success of reproduction, whereas the effect of anemophily is very weak. And the seed germination rate of inbred line progenies was lower than that of hybrid progenies, which is suspected to be caused by inbreeding depression. The research will provide scientific information for the protection and conservation of V. negundo var. heterophylla from the point of view of reproduction. In sum, the results are necessary to protect animal vectors in the background of insect decline.

Reproductive ecology of Dianthus inoxianus: A rare wild carnation with a specialized pollination system

Plants with specialized pollination systems may be susceptible to reproductive failure when pollinator service is unpredictable. This can influence the selection of floral traits that promote outcrossing in the presence of pollinators and selfing in their absence. Limited evidence exists regarding the association between specialized pollination and reproductive assurance, necessitating further investigation. We studied the reproductive biology of Dianthus inoxianus, a rare Mediterranean carnation endemic to a semi-arid region in SW Spain. D. inoxianus exhibited protandrus flowers and additional phenotypic signs of specialization for nocturnal pollination. Nectar sugar concentration remains relatively constant throughout the day (average 33.4%), while the standing crop varies considerably (average 1.5 μL/flower), peaking in the late afternoon and early evening. Controlled hand pollinations revealed that D. inoxianus is fully self-compatible, with similar reproductive success in autogamous, geitonogamous, and allogamous crosses. However, a small proportion of bagged flowers exhibited autonomous selfing. To assess the impact of presumed nocturnal pollination, we studied reproductive fitness and flower visitors over five years in three populations. Over 210 h of pollinator censuses, the hawkmoth species Hyles livornica and Macroglossum stellatarum, which were mainly dusk-active, accounted for > 95% of flower visits. Fruit and seed set positively correlated with hawkmoth visitation rate across years and populations. Additionally, pollinator exclusion experiments demonstrated that reproduction relies predominantly on nocturnal pollinators. However, under natural conditions, D. inoxianus also showed a non-negligible degree of autonomous self-pollination, with fruit- and seed-set being equivalent in absence of pollinators or under diurnal pollinators. We found evidence of an ecologically specialized pollination system and capacity for autonomous selfing, a combination that may enable the persistence of this taxon in a markedly unpredictable pollination environment.

Drought and temperature stresses impact pollen production and autonomous selfing in a California wildflower, Collinsia heterophylla

AbstractOngoing climatic changes have altered growing conditions for plants by limiting water availability and inducing unprecedented temperature increases, eliciting plant functional responses that compromise floral trait expression, reduce pollen production and promote early self‐pollination. In a controlled greenhouse study, plants of Collinsia heterophylla, an annual mixed‐mated hermaphrodite, were grown under temperature and water stresses. Floral trait responses and related effects on plant reproductive success were recorded. Plants grown under temperature and water stresses were shorter and had fewer leaves at flowering than control plants. Temperature‐stressed plants flowered earlier and had smaller flowers that produced fewer per capita pollen grains than control and water‐stressed plants. While lifetime flower production in plants experiencing temperature stress alone or water stress alone was similar to control plants, those receiving combined temperature and water stresses had significantly lower lifetime flower production. Abiotic stress did not affect investment in female traits such as ovule number per flower, but impacted male traits seen as fewer pollen grains per flower. In plants experiencing abiotic stress, an increase in autonomous self‐pollination was facilitated through a compromise in herkogamy, a sexual interference mechanism that promotes cross‐pollination. Spatial separation between stigma and anther, a measure of herkogamy was zero or negative in stressed plants. Thus, abiotic stress responses in plants did not compromise plant reproductive success as autonomous selfing was augmented. In nature, such responses will likely reduce available nutrition for pollinators through decreased flower and pollen production.

Polychorous Puncture Vine Tribulus terrestris L. (Zygophyllaceae), a potential forage source for a guild of insect pollinators during the wet season

Tribulus terrestris is a herbaceous weed capable of growing throughout the year in many habitats. It is hermaphroditic, protogynous, and self-pollinating, although it is also insect-pollinated. The insects involved in pollination use their flowers as a potential forage source by displaying fidelity during the wet season when profuse flowering occurs. The functional traits relating to sexual reproduction such as autonomous selfing, insect-pollination, polychory, and C4 photosynthetic pathway are quite advantageous for the plant to grow as a successful weed in different habitats, prominently in open habitats.

The reproductive traits that contribute to the invasive success of Mediterranean onionweed (Asphodelus fistulosus)

Background and aims – Understanding the traits that lead to the invasion potential of invasive alien species (IAS) provides insight for their management. The reproductive traits of IAS help us understand the mechanisms that allow for their invasive potential, and colonization into new ranges. Asphodelus fistulosus is a native Mediterranean species commonly found invading Australia, South-East Asia, South Africa, and North America. Materials and methods – Two populations of A. fistulosus in the Chihuahuan Desert were monitored for reproductive phenology. Floral visitors and their behaviour were described, and we assessed the breeding system through floral morphological characters and the mating system in controlled pollination experiments. Key results – Reproductive phenology showed continuous reproduction throughout the year. Floral morphology suggested a facultative autogamous breeding system, but the mating system was mixed with autonomous selfing. Flowers lasted one day, with anthesis lasting 11 h. Floral visitors of A. fistulosus consisted of a variety of taxa including species of Coleoptera, Hymenoptera, and Lepidoptera, the exotic Apis mellifera being the most frequent visitor. Conclusions – The reproductive traits of A. fistulosus in the invaded range provide the biological potential for further invasion. The continuous production of reproductive structures attracts many diverse pollinators, and the autonomous self-pollination implies that a single plant has the potential to develop a new population, which makes the control of this IAS a global challenge.

Covariation among reproductive traits in flowering plants shapes their interactions with pollinators

Abstract Globally, plants display enormous variation in life‐history strategies and trait combinations. However, evidence suggests that evolutionary and physiological constraints limit the number of plant ecological strategies. Although there have been recent advances in understanding correlations among plant traits, reproductive traits are rarely considered, despite their key role in shaping plant life‐history strategies and interactions with pollinators. Here, using a global dataset of 18 reproductive traits for 1506 species, we investigate the reproductive spectrum of flowering plants to identify how it shapes interactions with pollinators. We show that over 50% of all trait variation is explained by the first two reproductive axes, which represent the negative correlation between flower number and flower size, and the negative correlation between autonomous selfing and floral display size. In addition, these reproductive axes were associated with the identity and number of visits of the distinct pollinator guilds. However, reproductive axes explain a relatively small amount of variance in pollinator interactions highlighting the need to incorporate other factors along with reproductive traits to fully explain large‐scale patterns of plant–pollinator interactions. Our study identifies the major reproductive trait correlations in flowering plants and their role in shaping plant–pollinator interactions at a macro‐ecological scale. These findings emphasise the importance of considering reproductive traits in the global spectrum of plant form and function, and the need to explore beyond floral morphological traits to broaden our understanding of plant–pollinator interactions. Read the free Plain Language Summary for this article on the Journal blog.

Floral biology, pollination vectors and breeding system of Zieria granulata (Rutaceae), an endangered shrub endemic to eastern Australia

Context Understanding the factors that influence viable-seed production is crucial in the conservation of threatened plant species, yet these factors are often poorly understood. Aims We investigated the reproductive biology of Zieria granulata C.Moore ex Benth., an endangered Australian endemic with a limited distribution, with the intent of improving conservation and restoration outcomes. Methods Components of floral biology, including floral ontogeny and nectar production, were quantified to determine the pollination syndrome and the likely breeding system. Flower-visitor surveys (using both digital video recordings and human observations), a manipulative wind-pollination experiment and hand-pollination experiments were conducted to investigate pollination vectors and confirm the breeding system. Key results Z. granulata flowers were small, white, protandrous and produced highly ornamented pollen grains and small quantities of nectar; these characteristics suggest that the species fits the general entomophily syndrome. All floral visitors were arthropod species and of the 72 visitors observed, predominantly from the Dipteran and Hymenopteran families, 18 could be regarded as potential pollinators. Failure of simulated wind gusts (40 km h−1) to transport pollen ≥5 cm indicated that anemophily is unlikely for this species. Autonomous and manipulative selfing did not result in viable seed set, indicating that this is an obligate outcrossing species. However, fruit and viable-seed production was highly variable within and among some other treatments. Pre-dispersal seed predation was recorded at all study sites. Conclusions Pre-dispersal seed predation was recorded at all study sites and is a likely factor inhibiting viable-seed production. Implications This knowledge will be used to improve seed yield for collections used for ex situ conservation and restoration programs for the endangered Z. granulata.

Stamen curvature and temporal flower closure assure reproductive success in an early-spring-flowering perennial in the cold desert of Middle Asia.

Floral organ movements that ensure autonomous selfing are likely to occur in species that grow in habitats with pollinator scarcity and/or an unpredictable environment. Stamen curvature and temporal flower closure are two important floral behaviors that can influence plant pollination mode and reproductive success. However, both behaviors are rarely reported within a species, and little is known about how these two movements of floral organs ensure reproductive success in an unpredictable early spring environment with few pollinators. The aim of this study was to assess whether stamen curvature and temporal flower closure ensure successful reproduction of Leontice incerta in its cold desert habitat. Flowering phenology, floral traits, stamen curvature patterns and flower visitors were surveyed. The breeding system, capacity and timing for autonomous selfing were estimated by pollination manipulations. The timing of floral opening and closure, and benefits of temporal flower closure were determined. We found that flowering of L. incerta began in late March to early April in two populations in two years, and the yellow flowers had neither nectar nor scent. Floral visitation occurred very rarely, but bees (Colletes sp.) were potential pollinators. Fruit and seed set of open and bagged flowers did not differ significantly from that of self-pollinated or cross-pollinated flowers. However, removal of stamens significantly decreased seed set. Self-pollination occurs when the stamens curve and anthers touch the stigma autonomously, suggesting autonomous selfing assurance of seed production in this self-compatible species. Both fruit and seed set of flowers that were prevented from closing were significantly lower than those of control flowers and closed flowers treated with simulated rain treatment. Therefore, stamen curvature and temporal floral closure can ensure successful sexual reproduction of L. incerta in early spring in the cold desert, where lack of pollinators otherwise may lead to pollination failure.

Autonomous selfing is altered by pollination in delayed-selfing species Gentianopsis paludosa (Gentianaceae)

Autonomous selfing is altered by pollination in delayed-selfing species Gentianopsis paludosa (Gentianaceae)

Evolvability and constraint in the evolution of three-dimensional flower morphology.

Flower phenotypes evolve to attract pollinators and to ensure efficient pollen transfer to and from the bodies of pollinators or, in self-compatible bisexual flowers, between anthers and stigmas. If functionally interacting traits are genetically correlated, response to selection may be subject to genetic constraints. Genetic constraints can be assessed by quantifying standing genetic variation in (multivariate) phenotypic traits and by asking how much the available variation is reduced under specific assumptions about phenotypic selection on functionally interacting and genetically correlated traits. We evaluated multivariate evolvability and potential genetic constraints underlying the evolution of the three-dimensional structure of Dalechampia blossoms. First, we used data from a greenhouse crossing design to estimate the G matrix for traits representing the relative positions of male and female sexual organs (anthers and stigmas) and used the G matrix to ask how genetic variation is distributed in multivariate space. To assess the evolutionary importance of genetic constraints, we related standing genetic variation across phenotypic space to evolutionary divergence of population and species in the same phenotypic directions. Evolvabilities varied substantially across phenotype space, suggesting that certain traits or trait combinations may be subject to strong genetic constraint. Traits involved functionally in flower-pollinator fit and autonomous selfing exhibited considerable independent evolutionary potential, but population and species divergence tended to occur in phenotypic directions associated with greater-than-average evolvability. These results are consistent with the hypothesis that genetic constraints can hamper joint trait evolution towards optimum flower-pollinator fit and optimum self-pollination rates.

Rapid evolution of selfing syndrome traits in Viola arvensis revealed by resurrection ecology.

As part of global change, climate warming and pollinator decline are expected to affect plant phenology and plant-pollinator interactions. This paper aims at characterizing rapid evolution of life history traits and floral traits over two decades in the wild pansy (Viola arvensis), a common weed in agrosystems. We used a resurrection ecology approach with genotypes sampled in 1991 and 2012 from a population in Burgundy (France). The species has a mixed mating system (hereafter: mixed selfer) and presents a floral polymorphism. To correct for maternal effects, we measured plant traits in the second generation in a common garden (after a refreshing generation) to characterize plant evolution during the two decades. In addition, historical population selfing rates in 1991 and 2012 were inferred from microsatellites markers through heterozygote deficiency and identity disequilibrium. Phenotypic data revealed a significant advance in flowering date, reduced flower sizes and a higher propensity of plants to set seed by autonomous selfing. Moreover, we detected a change in color morph frequency with an increase of the pale morph frequency. In accordance with phenotypic data, the neutral genetic data revealed an increase in historical selfing rates from 0.68 in 1991 to 0.86 in 2012. Taken together, such data suggest that the wild pansy, a mixed selfer, is evolving a selfing syndrome that may be the consequence of reduced pollinator activity in agrosystems.

Red nectar presentation and characterization of the breeding system of an Andean nightshade

Flowers of Jaltomata weigendiana (Solanaceae) secrete red nectar that is visible through the partially translucent corolla. We report the pattern of nectar presentation during the sexual phases of the flower and characterize the breeding system. Comparison of flower sets experiencing daily removal starting Day 1 with flowers that accumulated nectar for one or two days prior to daily removal revealed no discernible effect on the life-of-the-flower nectar production, sugar production and floral longevity. Flowers produce about the same cumulative volume of nectar during the two sexual phases. However, cumulative nectar sugar production is about 4 times higher during the male phase. Nectar standing crop ranged from 4–26.6 µl for Day 1 flowers and 0–8.7 µl for flowers from which nectar was removed the previous day. With daily removal of nectar, 21 of 40 flowers contained no nectar during the last day of the flower’s life. All unmanipulated flowers developed fruits (autonomous self-pollination). However, manual self-pollinations and manual cross-pollinations resulted in fruits that weighed significantly more and had significantly more seeds than fruits produced by autonomous self-pollination. Protogyny and herkogamy promote cross-pollination, but delayed autonomous selfing at the end of the flower’s life ensures seed set if pollinator-mediated pollination fails.

Changes in female function and autonomous selfing across floral lifespan interact to drive variation in the cost of selfing.

PremiseMorphological and developmental changes as flowers age can impact patterns of mating. At the same time, direct or indirect costs of floral longevity can alter their fitness outcomes. This influence has been less appreciated, particularly with respect to the timing of selfing. We investigated changes in stigma events, autonomous selfing, outcross seed set capacity, and autofertility—a measure representing the potential for reproductive assurance—across floral lifespan in the mixed‐mating biennial Sabatia angularis.MethodsWe examined stigma morphology and receptivity, autonomous self‐pollen deposition, and seed number and size under autonomous self‐pollination and hand outcross‐pollination for flowers of different ages, from 1 d of female phase until 14 d. We compared autonomous seed production to maximal outcross seed production at each flower age to calculate an index of autofertility.ResultsThe stigmatic lobes begin to untwist 1 d post anthesis. They progressively open, sextend, coil, and increase in receptivity, peaking or saturating at 8–11 d, depending on the measure. Autonomous seed production can occur early, but on average remains low until 6 d, when it doubles. In contrast, outcross seed number and size start out high, then decline precipitously. Consequently, autofertility increases steeply across floral lifespan.ConclusionsChanges in stigma morphology and receptivity, timing of autonomous self‐pollen deposition, and floral senescence can interact to influence the relative benefit of autonomous selfing across floral lifespan. Our work highlights the interplay between evolution of floral longevity and the mating system, with implications for the maintenance of mixed mating in S. angularis.

Facilitated fecundity in sand flax: Pollination in an endangered herb of pine rocklands

Reproductive success in flowering plants depends on floral biology, breeding system, and availability of compatible mates and pollinators. Here, we examine the pollination biology of Linum arenicola (Small) H.J.P Winkler (Linaceae), sand flax, a federally endangered herb of pine rocklands in the Lower Florida Keys (USA). We observed the timing of floral anthesis, fruiting, florivory, and frequency of flower visits by insects. We compared fruiting in flowers that were open-pollinated, bagged to exclude floral visitors, and self-pollinated by hand to determine whether pollinator visits enhance or are necessary for reproduction. Fruit set was equally high between flowers open to pollinators and those that were hand-pollinated, but both were significantly higher compared to flowers from which pollinators were excluded. We observed that the wilting of petals late in the day in unvisited flowers often initiates self-pollination, but flowers are frequently visited by small bees and flies earlier in the day, suggesting that early day visits by those insects increase pollen deposition and potential for outcrossing. Despite high fruit set from autonomous self-pollination and occasional flower visitation, sexual reproduction is limited by herbivores: nearly half of all flowers produced were consumed by Key deer and galling midges. Optimum fruit set is not achieved from autonomous selfing alone, and pollinators play an important role in fruit production of the rare sand flax. Conservation efforts that enhance populations of suitable pollinators could increase the likelihood of fruit set from a diversity of pollen parents in rare plants like the endangered sand flax.

How early does the selfing syndrome arise? Associations between selfing ability and flower size within populations of the mixed-mater Collinsia verna.

PremiseWidespread associations between selfing rate and floral size within and among taxa suggest that these traits may evolve in concert. Does this association develop immediately because of shared genetic and/or developmental control, or stepwise with selection shaping the evolution of one trait following the other? If the former, then association ought to appear within and across selfing populations. We explore this fundamental question in three populations of the mixed‐mater Collinsia verna where autonomous selfing (AS) ability has been shown to be under selection by the pollination environment.MethodsWe grew clonal replicates of C. verna in a controlled environment to characterize broad‐sense genetic correlations among traits within populations and to assess whether divergence in mating system and floral traits among these populations is consistent with their previously observed selection pressures.ResultsAs predicted by their respective pollination environments, we demonstrate significant genetic divergence among populations in AS ability. However, patterns of divergence in floral traits (petal, stamen, and style size, stigmatic receptivity, and stigma‐anther distance) were not as expected. Within populations, genetic variation in AS appeared largely independent from floral traits, except for a single weak negative association in one population between flower size and AS rate.ConclusionsTogether, these results suggest that associations between selfing rate and floral traits across Collinsia species are not reflected at microevolutionary scales. If C. verna were to continue evolving toward the selfing syndrome, floral trait evolution would likely follow stepwise from mating system evolution.

高山物种栗色鼠尾草(Salvia castanea Diels)访花昆虫多样性与传粉行为变化

PDF HTML阅读 XML下载 导出引用 引用提醒 高山物种栗色鼠尾草(Salvia castanea Diels)访花昆虫多样性与传粉行为变化 DOI: 10.5846/stxb202101070071 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院战略生物资源科技支撑体系运行专项（ZSZY-001）；上海市科委科技计划项目（20392000600）；上海市绿化和市容局辰山专项课题（G172410，G182409） Diversity of visiting insects and changes of pollinator behavior in alpine species Salvia castanea Diels (Lamiaceae) Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:唇形科鼠尾草属是世界性分布、物种多样性丰富的大类群，具有独特的传粉模式和多样化的生态类型及繁殖策略，以往对鼠尾草属的花结构和雄蕊杠杆的生态功能、雄蕊杠杆机制对传粉者空间变异的进化响应和表型选择等方面已有较深入的研究，但至今对分布于不同区系代表性物种的传粉者组成、访花行为和繁育系统特征仍知之甚少。对分布于喜马拉雅东段至横断山高海拔地区栗色鼠尾草的传粉生态、交配系统和繁殖特性进行了研究，分析了2014年至2016年的年际间、2014年晴天和阴雨天的传粉者组成和传粉行为变化，探讨了这些变化对繁殖成功的影响。研究结果表明：3年共发现栗色鼠尾草有9种访花昆虫，传粉者组成及其行为变化较为明显。2014年有桔尾熊蜂Bombus friseanus、灰熊蜂B.grahami、圣熊蜂B.religiosus和中华蜜蜂Apis cerana 4种有效传昆虫，2015年仅有桔尾熊蜂是有效传粉者，而2016年的有效传粉昆虫改变为灰熊蜂和圣熊蜂。栗色鼠尾草的盗蜜现象较为普遍，主要盗蜜昆虫为灰熊蜂和桔尾熊蜂。桔尾熊蜂访花行为的年际变化较大，受天气条件的影响明显，同时其有效传粉行为可能显著影响了灰熊蜂的盗蜜行为。栗色鼠尾草的繁育系统为专性异交，主要依靠传粉者进行授粉，缺少传粉者时低程度的主动自花授粉可为其提供繁殖保障，且没有花粉限制和近交衰退。研究揭示了在高海拔地区，多变的天气条件可能显著影响着鼠尾草属植物的传粉者种类组成、访花行为和传粉效率，进而影响植物的繁殖成效和种群稳定。有效传粉频率是保证栗色鼠尾草较高自然结实率的主要因素，在一定程度上，盗蜜强度对繁殖成功具有中性的影响。本研究结果为阐明高山鼠尾草物种的繁殖如何受气候环境变化的影响，以及保证繁殖成功的可能策略奠定基础。 Abstract:Salvia L. (Lamiaceae) is a worldwide genus with rich species diversity, a variety of habitat types and unique pollination mode. Previous studies have focused on flower structure and ecological function of stamen lever mechanism, the evolutionary response of stamen lever mechanism to spatial variation in pollinators and phenotypic selection of Salvia. However, the pollinator's compositions, behavior and reproductive success of representative Salvia species distributed in different flora have been rarely studied. We studied the pollination ecology, breeding system and reproductive characteristics of Salvia castanea, which is widely distributed from the eastern Himalayas to the Hengduan Mountains, we analyzed the composition of pollinators and the interannual changes of pollinator behavior from 2014 to 2016, the daily changes between sunny and rainy days in 2014, and discussed their effects on the reproduction. The results showed that a total of 9 species of visiting insects were found in Salvia castanea during three years and the change of pollinator's composition and their behavior was obvious. In 2014, S. castanea was legitimately visited by four species including Bombus friseanus, B. grahami, B. religiosus, and Apis cerana. In 2015, the pollinators were reduced to only one species, B. friseanus, however, in 2016, there were two legitimate pollinators, B. grahami and B. religiosus. The nectar robbery is common in S. castanea, and the main robbers are B. grahami and B. friseanus. We found that visiting behavior of B. friseanus showed inter-annual variation and was largely affected by climate, while the nectar robbery of B. grahami probably was affected by activities of B. friseanus. The breeding system for S. castanea was obligate outcrossing, which mainly depended on pollinators for seed set. In the absence of pollinators, low degree of autonomous selfing can provide reproductive assurance for S. castanea, and there was no pollen-limitation and inbreeding depression. Our results revealed that in alpine regions, climate was changeable and weather conditions significantly affected composition of pollinators visit behavior and pollination efficiency, which might, in turn affect reproductive success and population stability of plants. Legitimately, visitation rate is the main factor for ensuring high seed set of S. castanea in open pollination condition, and nectar robbery could maintain a neutral effect on reproductive success at a certain level. Our results of this study provide valuable insights for illustrating how the reproduction of alpine Salvia species is affected by climate and environmental changes and reproductive strategies to ensure reproductive success. 参考文献 相似文献 引证文献