Pollinator and Flower Morphology Interact to Affect Pollen Receipt.

Pollen limitation reduces seed production and may reduce plant population growth rate. Plants may be particularly prone to pollen limitation if they require pollinators, occur at high elevation, and have human-mediated reductions in plant density due to harvesting. We found that two rare monocarpic Tibetan plant species, known as the Himalayan Snow Lotus, both require pollinators and that seed production in Saussurea medusa (Asteraceae) but not S. laniceps is limited by pollen receipt. We created deterministic and stochastic stage-structured matrix models for S. medusa, and found that pollen supplementation significantly increases population growth rate. However, even when pollen is not limiting, S. medusa is likely at risk for extinction in the next 50 years. Our results for this monocarpic plant differ from other population studies on pollen limitation in polycarpic plant species since the magnitude of pollen limitation for seed production was relatively low, and yet the sensitivity of population growth to changes in seed production was relatively high.

Pollen movement is a crucial component of dispersal in seed plants. Although pollen dispersal is well studied, methodological constraints have made it challenging to directly track pollen flow within multiple populations across landscapes. We labeled pollen with quantum dots, a new technique that overcomes past limitations, to evaluate the spatial scale of pollen dispersal and its relationship with conspecific density within 11 populations of Clarkia xantiana subsp. xantiana, a bee-pollinated annual plant. We used experimental arrays in two years to track pollen movement across distances of 5-35 m within nine populations and across distances of 10-70 m within two additional populations. We tested for distance decay of pollen dispersal, whether conspecific density modulated dispersal distance, and whether dispersal kernels varied among populations across an environmentally complex landscape. Labeled pollen receipt did not decline with distance over 35 m within eight of nine populations or over 70 m within either of two populations. Pollen receipt increased with conspecific density. Overall, dispersal kernels were consistent across populations. The surprising uniformity in dispersal distance within different populations was likely influenced by low precipitation and plant density in our study years. This suggests that spatiotemporal variation in the abiotic environment substantially influences the extent of gene flow within and among populations.

Long-tubed hawkmoth-pollinated species present some of the most remarkable examples of floral specialization depending exclusively on long-tongued hawkmoths for sexual reproduction. Nonetheless, long-tongued hawkmoths do not rely exclusively on specialized plants as nectar sources, which may limit sexual reproduction through pollen limitation. However, very few studies have quantified the level of pollen limitation in plants with highly specialized floral traits in tropical regions. In this context, we studied four sympatric hawkmoth-pollinated species in a highland Atlantic Rain forest and assessed pollen limitation and their dependence on pollinators by analyzing the floral biology, breeding system, pollination mechanisms, and abundance of long-tongued pollinators. We showed that the four species are self-compatible, but are completely dependent on long-tongued hawkmoths to set fruits, and that flower visitation was infrequent in all plant species. Pollen limitation indices ranged from 0.53 to 0.96 showing that fruit set is highly limited by pollen receipt. Long-tongued moths are much less abundant and comprise only one sixth of the hawkmoth fauna. Pollen analyses of 578 sampled moths revealed that hawkmoths visited ca. 80 plant species in the community, but only two of the four species studied. Visited plants included a long-tubed hawkmoth-pollinated species endemic to the lowland forest ca. 15-20 km away from the study site. Specialization index (H 2 ' = 0.20) showed that community-level interactions between hawkmoths and plants are generalized. We suggest that sexual reproduction of these highly specialized hawkmoth-pollinated species is impaired by competition among plants for pollinators, in conjunction with the low abundance and diversity of long-tongued pollinators.

Many organisms exhibit parental optimism, producing more of the initial stages of offspring (e.g., eggs, embryos) than they can usually mature. For plants, parental optimism may be linked to the risk of seed production being limited by pollen receipt (pollen limitation). Here we elaborate a stochastic model of pollen limitation developed by Haig and Westoby ( 1988 ) and Burd ( 2008 ) and link it with published data on the magnitudes of prepollination costs versus postpollination costs of seed production in 80 plant species. We demonstrate that parental optimism should be expected when prepollination costs of seed production are small relative to postpollination costs. This was observed for most (62 of 80) of the plant taxa surveyed. Under parental optimism, plants overinvest in securing fertilized ovules, and consequently pollen limitation is predicted to be uncommon. However, for a sizable minority of plant species (18 of 80), prepollination costs approach or exceed postpollination costs. For these species, parental pessimism is instead optimal. Parents initiate fewer zygotes than they can usually mature, and pollen limitation is predicted to be severe. Because the relative magnitudes of prepollination and postpollination costs vary by more than 1,000-fold across plant taxa, parental outlook (optimism vs. pessimism) and levels of pollen limitation are predicted to vary widely.

The plant-colonized microbial communities have closely micro-ecological effects on host plant growth and health. There are many medicinal plants in the genus Hedyotis, but it is yet unclear about the shoot-assembled bacterial and fungal communities (SBFC) of Hedyotis plants. Hence, eight plant populations of Hedyotis diffusa (HD) and H. corymbosa (HC) were evaluated with 16S rRNA gene and ITS sequences, for comparing the types, abundance, or/and potential functions of SBFC at plant species- and population levels. In tested HD- and HC-SBFC, 682 fungal operational taxonomic units and 1,329 bacterial zero-radius operational taxonomic units were identified, with rich species compositions and varied alpha diversities. Notably, the SBFC compositions of HD and HC plant populations were exhibited with partly different types and abundances at phylum and genus levels but without significantly different beta diversities at plant species and population levels. Typically, the SBFC of HD and HC plant populations were presented with abundance-different biomarkers, such as Frankiaceae and Bryobacteraceae, and with similar micro-ecological functions of microbial metabolisms of lipids, terpenoids,and xenobiotics. Taken together, HD- and HC-SBFC possessed with varied rich compositions, conservative taxonomic structures, and similar metabolic functions, but with small-scale type and abundance differences at plant species- and population- levels.

The effects of floral morphology on rates of pollen removal and deposition by different pollinators in generalist plant species are not well known. We studied pollination dynamics in wild radish, Raphanus raphanistrum, a plant visited by four groups of pollinators: honey bees, small native bees, butterflies, and syrphyd flies. The effects of anther position and other factors on pollen removal during single visits by all four pollinator taxa were measured. Flowers with high anther exsertion (i.e., anthers placed higher above the opening of the corolla tube) tended to have the highest numbers of pollen grains removed, but this effect was strongest for honey bees and butterflies. For all pollinator taxa, pollen removal increased with the number of pollen grains available on a flower and whowed a positive, decelerating relationship with the duration of the visit. The effects of stigma position and other factors on pollen deposition during single visits by honey bees and butterflies were also studied. The nectar-feeding butterflies had a higher pollination efficiency (percentage of pollen grains removed from anthers that were subsequently deposited on a stigma) than the nectar- and pollen-feeding honey bees. Flowers with intermediate stigma exsertion had the highest numbers of pollen grains deposited on their stigmas by butterflies, but stigma exsertion had no effect on deposition by honey bees. For both butterflies and honey bees, pollen deposition on the recipient flower increased with the amount of pollen removed from the donor flower, and there was a positive, decelerating relationship between deposition and time spent at the flower; these results are analogous to those for pollen removal. The effects of anther and stigma exsertion on pollen removal and denosition did not fit predictions based on patterns of floral correlations, but results for morphology, pollen availability, time spent per visit, and pollinator efficiency are in broad agreement with previous studies, suggesting the possible emergence of some general rules of pollen transfer.

Coevolution refers to evolutionary changes in the traits of two or more interacting species caused by reciprocal natural selection. Geographic mosaic theory of coevolution (GMC) proposes that the dynamics of coevolution between pairs or group of species often occur at different geographic scales. There are three hypotheses on the coevolutionary process. (1) Different evolutionary interaction trajectories among populations are likely to generate a selection mosaic. (2) A mixture of coevolutionary hotspots and coldspots. Hot spots are the subset of communities in which much of the coevolutionary change occurs and coldspots refer to areas where coevolutionary selection hardly occurs or completely does not occur. (3) There is a continual population remixing of the range of coevolving traits, resulting from the selection mosaic, coevolutionary hotspots, gene flow, random genetic drift, and local extinction of subpopulations. Studies of GMC between plants and pollinators indicate that shifts of effective pollinators among different geographic populations may cause divergence in floral traits (i.e., pollination ecotype). Changes of pollinator assemblages or species components have been illustrated coevolving with floral morphology or reward among populations from different altitudes or habitats. Here, recent case studies of GMC between plants and pollinators are grouped into five categories: Floral morphology and pollinator components, corolla tube/nectar spur and pollinator feeding structure, floral color, floral scents, floral rewards and pollinator assemblages. Floral tube or nectar spur length is positively related to pollinator body structures, such as the proboscis and leg length. The adaptation of flower color and pollinator vision provides a series of examples for the GMC. With the increase of altitude, flower color changed from blue and ultraviolet blue adapted to bee vision to blue-green and green adapted to fly vision. Recent study indicated that the difference in cycad odor components related to a shift of beetle species in different regions, suggesting a potential coevolutionary relationship between flower odor and pollinators. Studies showed that where bees foraged more nectar, flowers secreted more nectar, suggesting that floral reward amounts and types coevolve with pollinators among different geographic populations. An examination of GMC in plant-pollinator interactions involves three steps in general: (1) Detection of the relationship between floral traits and pollinator shift or body structure. (2) Transplanting experiments to detect differences in seed set between native phenotypes and transplanted phenotypes. (3) Single pollinator visit experiment to detect pollen output differences between native and transplanted phenotypes. Experimental evolutionary biology not only can test whether floral variation is related to pollinator shifts, but also make people aware of the impact of the reduction or loss of pollinators on the evolutionary consequences. To illustrate GMC between plants and pollinators, it is essential to isolate the evolutionary changes in traits caused by biotic factors or abiotic factors in future. It would be highly appreciated if genome scans and analysis are used in further studies to explore the genome-wide patterns of GMC between plants and pollinators.

To understand the relationships between floral morphologies and the reproductive strategies of plants, the contributions of multiple pollinators to plant reproductive success need to be examined. To outline recent advances on this topic, we review studies of five bumblebee‐pollinated plants in Japan. These plant species are pollinated by one to three bumblebee species differing in proboscis length: Bombus consobrinus, Bombus diversus and Bombus honshuensis. These pollination systems allow us to compare the reproductive strategies of plants pollinated by single and multiple bumblebee species. First, we address the effects of morphological correspondence between flowers and pollinators on the reproductive success of plants. In plants with narrow tubular flowers, Isodon umbrosus and Clematis stans, pollination effectiveness depended on the morphological correspondence between floral tube length and pollinator mouthparts. These flowers are subject to varied directions and intensities of selection by multiple bumblebee species, resulting in the maintenance of large variation in floral morphology within and between populations, and even within individuals. In contrast, pollination effectiveness in plants having flowers with a wide entrance, Melampyrum roseum and Hosta sieboldiana, did not differ among bumblebee species because of good correspondence between floral morphology and bumblebee body size, resulting in small morphological variations among flowers. Thus, generalized pollination systems with multiple pollinator species favor floral traits that enable the use of various pollinators. Second, we address the quantity and quality of the pollination service in bumblebee‐pollinated plants. Isodon umbrosus, with its generalized pollination system, suffered from pollen limitation because of low pollination quality. In contrast, Isodon effusus, which has a specialized pollination system, suffered from pollen limitation because of low pollination quantity. Isodon umbrosus produced large numbers of short tubular flowers to improve pollination quantity, whereas I. effusus produced small numbers of long tubular flowers to improve pollination quality, resulting in a clear trade‐off between the size and number of flowers within plants. In M. roseum, which has a generalized pollination system, three bumblebee species achieved sufficient pollination, but seed production was limited by an increased rate of self‐pollination. This is because this species invests more resources in cross‐pollinated seeds by selective abortion of selfed seeds. Our results demonstrate that the strategy of generalized plants is to improve pollination quantity, whereas the strategy of specialized plants is to improve pollination quality.

The role of pollinators in floral divergence has long attracted the attention of evolutionary biologists. Although abundant studies have reported the effect of pollinators on flower-shape variation and plant speciation, the influence of pollinators on plant species differentiation during rapid radiations and the specific consequences of shifts among similar pollinators are not well understood. Here, we evaluate the association between pollinators and floral morphology in a closely related and recently diversifying clade of Linaria species (sect. Supinae subsect. Supinae). Our approach combined pollinator observations, functional floral morphometric measures and phylogenetic comparative analyses. The fauna visiting Linaria species was determined by extensive surveys and categorized by a modularity algorithm, and the size and shape of flowers were analysed by means of standard and geometric morphometric measures. Standard measures failed to find relationships between the sizes of representative pollinators and flowers. However, discriminant function analyses of geometric morphometric data revealed that pollination niches are finer predictors of flower morphologies in Linaria if compared with phylogenetic relationships. Species with the most restrictive flowers displayed the most slender spurs and were pollinated by bees with larger proboscides. These restrictive flower shapes likely appeared more than once during the evolutionary history of the study group. We show that floral variation can be driven by shifts between pollinators that have been traditionally included in a single functional group, and discuss the consequences of such transitions for plant species differentiation during rapid radiations.

Much effort has been spent on the conservation of rare, threatened, and endangered plants in the biodiversity hotspot of the California Floristic Province, however little is known about the identity of their pollinators. In this study we provide the first formal study on the identity of the invertebrate pollinators of five rare endemic island plant species from San Clemente Island, the southernmost of the California Channel Islands: Delphinium variegatum ssp kinkiense, Lithophragma maximum, Malacothamnus clementinus, Malva assurgentiflora ssp glabra, and Sibara filifolia. We surveyed plant-pollinator interactions at populations of each focal plant species using timed sweep-netting. We used pollinator capture data to compile bipartite interaction networks for each plant population, and calculated centrality indices (degree, betweenness centrality, and closeness centrality) of pollinators to identify species important to network stability. We found a significant effect of pollinator taxonomic group (fly, bee, wasp, or Lepidopteran) on some indices of pollinator centrality in interaction networks, and variation in pollinator centrality between different locations. Hoverflies, moths, and butterflies were important generalists with higher network centrality across all plant populations, while bees tended to be more specialists within their networks, except for the Malva assurgentiflora ssp glabra network, where bees were on average of higher centrality than flies. We recommend targeted restoration practices for future study that could support pollination both directly and indirectly to focal rare plant species of conservation interest across plant populations. These practices could augment general pollinator conservation best practices such as reducing pesticide use and planting native plant species to provide increased pollination to endangered plants.

Floral nectar plays a critical role in shaping the ecology and evolution of plant-pollinator interactions. Effective and efficient methods that allow for broad-scale sampling of nectar volume and sugar concentration across a diversity of taxa are needed to improve our understanding of many dimensions of mutualistic plant-pollinator interactions—including their basic ecology and evolution, their responses to environmental change, and their conservation and restoration. Despite the key importance of nectar for mediating plant-pollinator interactions, quantifying floral nectar in the field from many different plant species is challenging because there is often no one-size-fits-all sampling method that is effective across a diversity of floral structures and nectar traits. Different methods require different preparation, and sampling from many species involves a variety of logistical challenges. Here we provide a methodological roadmap for sampling floral nectar in the field from many different plant species. We describe our nectar collection methods in detail, including necessary equipment, calculations, and approaches appropriate for different floral morphologies. We also provide a troubleshooting guide for common problems encountered while collecting nectar in the field. To demonstrate the utility and effectiveness of our methods for collecting nectar from many different species, we present results on nectar trait variation from 53 species in an ecosystem. Our method illustrates that nectar traits vary considerably within and among plant species, indicating that large-scale nectar sampling projects are an important consideration for many basic and applied questions in pollination ecology and evolution. We hope that across many plant communities and ecosystems, our paper provides a practical roadmap for how to navigate the complexities of quantifying floral nectar traits.

PDF HTML阅读 XML下载 导出引用 引用提醒 动物分散贮食行为对植物种群更新的影响 DOI: 10.5846/stxb201405301116 作者: 作者单位: 东北林业大学野生动物资源学院,东北林业大学野生动物资源学院,东北林业大学野生动物资源学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31372209);中央高校基本科研业务费专项资金(2572014CAY01);黑龙江省自然科学基金项目(C201131) Animal scatter-hoarding behavior and its impact on the regeneration of plant populations Author: Affiliation: College of Wildlife Resources,Northeast Forestry University,Harbin,150040,,College of Wildlife Resources,Northeast Forestry University,Harbin,150040 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:分散贮食是许多动物取食行为策略的重要组成部分。对以植物种子为主要贮食对象的动物来说,种子内营养物质含量、种子大小以及种子内次生化合物的含量等因素都直接影响动物的贮食行为。动物偏爱贮藏个体较大的种子,大种子多被搬运并分散贮藏在远离种源的地方,而小种子则多被就地取食,以补充动物贮食过程中的能量消耗。贮食动物主要通过空间记忆、特殊路线以及贮藏点周围的直接线索等途径重新获取贮藏点内食物。在重取过程中,一些贮藏点被遗忘,其中的种子成为植物种群更新的潜在种子库。因此,分散贮食动物不仅是种子捕食者,还是种子传播者,它们对植物种子的捕食、搬运和贮藏,影响了植物种子的存活和幼苗的建成,从而在一定程度上影响植物种群的更新、分布。植物种群为了促进种子的传播,在进化过程中逐渐形成了形式多样的适应性策略,降低种子的直接被捕食率,提高种子的被贮藏率。研究动物分散贮食行为对植物种群更新的影响,将有助于理解贮食动物与植物之间的互惠关系,从而认识贮食动物种群在生态系统中的作用,为生物多样性的保护提供科学依据。 Abstract:Scatter-hoarding is one of the most important foraging strategies for many animals. For animals whose hoarding targets are seeds, the hoarding behavior is directly affected by many factors relevant to seeds, including their size, the nutrient content, and secondary metabolites inside the seeds. Animals prefer larger seeds that are delivered and scatter-hoarded somewhere far away from the food sources. Smaller seeds are eaten on the spot by animals in compensation for the energy consumed during the hoarding process. Hoarding animals retrieve the food at the cache sites mainly according to the following: spatial memory, particular paths, and direct clues around the cache sites. During the retrieval process, some cache sites are forgotten or missed by the hoarding animals, and these seeds become potential pools for the regeneration of some plant populations. Therefore, scatter-hoarding animals play two roles in ecological systems: they are not only consumers, but also circulators, of seeds. The serial behavior of scatter-hoarding animals (i.e., retrieval, delivery, and storage), directly influence both the survival of seeds and creation of seedlings. Furthermore, to some degree, the regeneration and distribution of certain plant populations are affected by the behavior of scatter-hoarding animals. As for plant populations, the most urgent mission is to protect their own seeds. In other words, in order to avoid being consumed and to decrease the forage rate by animals, the plant populations have gradually formed multiple and various adaptive strategies during the evolutionary process. Following a brief statement of conception and research background of hoarding behavior, the main text of this paper comprises four parts. In the first part, the evolution of scatter-hoarding behavior is discussed. In the second part, the process of scatter hoarding is divided into four sections. First, we consider how hoarding animals select their hoarding targets, including (i) the determination of seed quality by hoarding animals, (ii) the effect of nutrients inside the seeds on animal hoarding, (iii) the effect of seed size on animal hoarding, and (iv) the effect of secondary metabolites inside the seeds on animal hoarding. Second, we consider the delivery and storage of seeds by animals. Third, we review the retrieval behavior of hoarding animals (e.g., spatial memory, particular path, and relevant direct clues). In the third part of the paper, we elaborate the influence of animal scatter-hoarding behavior on the regeneration of plant populations. A number of problems are discussed in detail (i.e., the dispersion effect of scatter-hoarding animals on plant seeds, the dispersion mechanism of plant seeds, the negative effects of scatter-hoarding animals on plant populations, and the adaption strategies of plant populations.) In the last part of this paper, the substantial content is thoroughly summarized. Specifically, this paper is focused on animal scatter-hoarding behavior and its impact on the regeneration of plant populations. These results should be helpful for understanding the mutualism that exists between hoarding animals and plant species, thereby revealing the species-specific functions of hoarding animals in ecological systems. Ultimately, this paper is intended to provide a scientific basis for the protection of biodiversity. 参考文献 相似文献 引证文献

Floral nectar sugar composition is assumed to reflect the nutritional demands and foraging behaviour of pollinators, but the relative contributions of evolutionary and abiotic factors to nectar sugar composition remain largely unknown across the angiosperms. We compiled a comprehensive dataset on nectar sugar composition for 414 insect-pollinated plant species across central Europe, along with phylogeny, paleoclimate, flower morphology, and pollinator dietary demands, to disentangle their relative effects. We found that phylogeny was strongly related with nectar sucrose content, which increased with the phylogenetic age of plant families, but even more strongly with historic global surface temperature. Nectar sugar composition was also defined by floral morphology, though it was not related to our functional measure of pollinator dietary demands. However, specialist pollinators of current plant-pollinator networks predominantly visited plant species with sucrose-rich nectar. Our results suggest that both physiological mechanisms related to plant water balance and evolutionary effects related to paleoclimatic changes have shaped floral nectar sugar composition during the radiation and specialisation of plants and pollinators. As a consequence, the high velocity of current climate change may affect plant-pollinator interaction networks due to a conflicting combination of immediate physiological responses and phylogenetic conservatism.

Flower morphology, phenology and visitor patterns in an alpine community on Mt Olympos, Greece

Detection probability (p) in plants is imperfect in natural conditions due to several factors. This imperfect detectability is rarely accounted for in the estimation of demographic parameters, such as survival probabilities (S) or transition rates between different life states or size classes (ψ), which may result in inaccurate quantitative information about plant populations. In this study, we used previously collected data of five plant species belonging to different families with contrasting life forms and habitats (Flaveria chlorifolia, Mammillaria hernandezii, Neobuxbaumia macrocephala, Govenia lagenophora, and Castilleja tenuiflora), data simulations, multi‐state models (a demographic tool that explicitly accounts for p), and direct estimation of survival and transition rates (i.e., assuming perfect detection) to identify in which species, states, or demographic parameters the bias caused by ignoring our imperfect detectability is more severe. Detection was imperfect (p < 1) for all our study species. In general, ignoring detection probabilities yielded underestimated survival and transition rates in all five species. Biases caused by assuming perfect detection were also large and significant, mainly in inconspicuous life states and size classes, such as seedlings and dry individuals. In contrast, considering detection probabilities resulted in fewer underestimated survival and transition rates, with smaller and mostly nonsignificant biases. Intriguingly, some transitions were overestimated even when accounting for detection probabilities. Our findings highlight the importance of considering that detection of most plant species is imperfect in the field, even in species that are apparently conspicuous, to avoid incorrect inferences about plant populations.