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Premise: Fecundity and mating outcomes commonly differ among plant populations occupying contrasting environments. If self‐pollination occurs primarily among flowers within plants, contrasting reproductive outcomes among populations must reflect environmental effects on plant‐pollinator interactions. Specifically, local conditions could affect features of plant phenotypes that influence pollinator behavior, in turn modifying plant reproductive outcomes. Methods: We compared phenotypes, pollinator abundance and behavior, and female fecundity and mating in two meadow populations and two forest populations of Aconitum kusnezoffii within 3 km of each other. Mating outcomes were assessed using microsatellites. Results: Meadow plants generally produced more, shorter ramets with more, larger flowers, but less nectar per flower than forest plants. These differences likely largely represent phenotypic plasticity. Individual bumble bees visited more flowers on forest plants, likely because the more abundant bees in the meadows depleted nectar availability, as indicated by briefer visits to individual flowers. Despite similar fruit set in both habitats, forest plants set more seeds per fruit. Nevertheless, meadow plants produced more seeds overall, owing to sevenfold greater flower production. Consistent with individual bees visiting fewer flowers on meadow plants, more of their seeds were outcrossed. However, the outcrossed seeds of forest plants included more male mates. Conclusions: Reproductive outcomes can vary among populations of animal‐pollinated plants as a result of differences in the availability of effective pollinators and environmental effects on plant phenotypes, and their functional consequences for pollinator behavior that governs pollen dispersal. [ABSTRACT FROM AUTHOR]

A range of hypotheses seek to explain why conifers are infrequent in tropical rainforests. Here, we explore how the conifer, Podocarpus neriifolius, persists at low density in tropical lower montane rainforests of northern Thailand. Recruitment, growth and survival of seedlings and small saplings was monitored for 3.5 years in plots near and away from putative parent trees, and for large saplings and trees in a 16 ha forest plot over 8 years. Seeds and strobili were collected in litterfall traps for 2 years, and pollen rain extracted from forest floor moss samples. Demographic rates and ecophysiological traits of saplings were compared with co-occurring angiosperms Castanopsis acuminatissima and Calophyllum polyanthum. Survivorship was higher in the conifer for all size classes > 30 cm ht (0.97–0.99 y−1 vs. 0.92–0.98). Growth rate was similar for small saplings (9.3–12.6 cm y−1 ht), higher in P. neriifolius for large saplings (0.21 cm y−1 dbh vs. 0.11–0.12), but lower for trees (0.10 cm y−1 vs. 0.16–0.45). Canopy openness above saplings was similar amongst species (3.2–4.2%), whilst leaf N was lower (1.33% vs. 1.43–1.49%), and mass leaf per area (1.96 vs. 1.88) and δ13C higher (− 33.4 ‰ vs. – 34 to 34.9‰) for P. neriifolius. Pollen rain varied between plots, as did strobilus and seed fall between both plots and years, with highest pollen density, strobilus and seed fall close to parent trees, as were areas with highest seedling density and recruitment. High survivorship, high recruitment near parent trees and more widespread recruitment in mast years, offsets slower growth to ensure population persistence of P. neriifolius in angiosperm-dominated rainforest. Low stand density and patchy distribution is best explained by pollen limitation on seed production, with strong recruitment only where male and female trees occur in close proximity, and in mast seed years. [ABSTRACT FROM AUTHOR]

Bird pollination in Asia is regarded as an uncommon phenomenon and, therefore, only a few investigations on mating pattern and paternity in fruits of Asian bird-pollinated plants have been conducted. Here, we examined spatial genetic structure, pollen dispersal, and multiple paternity in a natural population of Bombax ceiba (B. ceiba) (Malvaceae) in Hainan Island, South China, using simple sequence repeat (SSR) markers. A low genetic diversity (H e = 0.351 ± 0.0341 and 0.389 ± 0.043, respectively, for adults and offspring) and bottleneck effects were observed. Genetic kinship was significant within 400 m or in 1,800–3,800 m. Both the mating pattern and paternity analysis confirmed obligate xenogamy and a low multiple paternity in B. ceiba. There was a strongly negative relationship between the frequency of matings and the distance between mating pairs. The average pollen dispersal distance was 202.89 ± 41.01 m (mean ± SE) and the farthest distance of > 1 km was recorded. Realized mating events showed an extremely leptokurtic distribution within 1,200 m, suggesting that the pollen dispersal distance was consistent with the optimal foraging theory of generalist birds such as Zosterops spp. and Pycnonotus spp. Paternity per tree ranged from two to six and the average effective number of pollen donors per maternal plant was 3.773, suggesting a low level of paternity diversity as compared to other bird-pollinated plants. We concluded that optimal foraging behavior by generalist birds could explain the leptokurtic pollen dispersal distribution and predominantly near-neighbor matings in B. ceiba. The limited pollen dispersal distance and low multiple paternity were consistent with low fruit setting rate (3.27 ± 0.93%) in this self-incompatible tree, which was caused mainly by the restricted flight distance of birds and human disturbances. Low genetic diversity and significant spatial genetic structure might have largely resulted from logging and human collection of fruits. [ABSTRACT FROM AUTHOR]

Background and Aims Hybridization is increasingly recognized as an integral part of the dynamics of species range expansion and contraction. Thus, it is important to understand the reproductive barriers between co-occurring species. Extending previous studies that argued that the rare Eucalyptus risdonii was expanding into the range of the surrounding E. amygdalina by both seed and pollen dispersal, we here investigate the long-term fitness of both species and their hybrids and whether expansion is continuing. Methods We assessed the survival of phenotypes representing a continuum between the two pure species in a natural hybrid swarm after 29 years, along with seedling recruitment. The performance of pure species as well as of artificial and natural hybrids was also assessed over 28 years in a common garden trial. Key Results In the hybrid zone, E. amygdalina adults showed greater mortality than E. risdonii , and the current seedling cohort is still dominated by E. risdonii phenotypes. Morphologically intermediate individuals appeared to be the least fit. Similar results were observed after growing artificial first-generation and natural hybrids alongside pure species families in a common garden trial. Here, the survival, reproduction, health and growth of the intermediate hybrids were significantly less than those of either pure species, consistent with hybrid inferiority, although this did not manifest until later reproductive ages. Among the variable progeny of natural intermediate hybrids, the most E. risdonii -like phenotypes were the most fit. Conclusions This study contributes to the increasing number of reports of hybrid inferiority in Eucalyptus , suggesting that post-zygotic barriers contribute to the maintenance of species integrity even between closely related species. However, with fitness rapidly recovered following backcrossing, it is argued that hybridization can still be an important evolutionary process, in the present case appearing to contribute to the range expansion of the rare E. risdonii in response to climate change. [ABSTRACT FROM AUTHOR]

Premise: Cleistogamous species constitute interesting study systems to resolve the longstanding question of how outcrossing is maintained given that seed production is ensured through selfing. In this work, we investigate the selective forces that allow the persistence of producing self‐pollinated cleistogamous (CL) and chasmogamous (CH) flowers in Viola jaubertiana Marès & Vigin. Methods: We monitored three populations at different elevation for two years, and studied the flowering phenology and the relative contribution of each flower morph to parental fitness. We tested whether allocation to CH and CL flowers differed across populations and if it covaried with herbivory and water stress conditions. We also performed hand‐pollination and bagging experiments in CH flowers to estimate inbreeding depression and heterosis. Results: The CH flowers open in winter under unfavorable conditions for pollination, show high pollen limitation and no‐delayed selfing, and thus produce a low amount of seeds. Conversely, CL flowers appear in early spring, are physiologically cheaper to produce (i.e., dry weight is 3.4 times lower than that of CH flowers), and yield approximately 100 times more seeds than CH flowers. The CH flowers were favored under water stress and low herbivory. Crosses between populations showed up to 25% greater fitness than those within populations. Conclusions: Despite the great pollen limitation in CH flowers, we suggest that the interaction among different environmental determinants and heterosis are probably sufficient forces to maintain chasmogamy in this long‐lived species, reducing deleterious fixed mutations in the selfed lines. [ABSTRACT FROM AUTHOR]

Keywords: Asian honey bees; Gnetum; gymnosperms; moths; nocturnal pollination; plant-insect interactions; pollen theft; tropical rainforests EN Asian honey bees Gnetum gymnosperms moths nocturnal pollination plant-insect interactions pollen theft tropical rainforests 1 4 4 12/03/21 20211201 NES 211201 Bees belong to modern groups of pollinators, which originated concurrently with new angiosperms (flowering plants), and might have contributed to the global gymnosperm-to-angiosperm turnover in the mid-Cretaceous (125-90 million years ago [Ma]; Cardinal and Danforth 2013, Peris et al. 2017). Our data suggest that diurnal honey bees disrupt the pollination of an insect-pollinated gymnosperm by reducing the pool of pollen available for nocturnal pollinators, resulting in decreased pollinator pollen loads and reduced seed set. Then, in bee-present season, we quantified honey bee visitation rate, pollen loads on honey bees and pollen remaining in anthers after honey bee visits to assess the intensity of theft. [Extracted from the article]

The presence of the field border (FB), such as roadways or unplanted areas, between two fields is common in Asian farming system. This study evaluated the effect of the FB on the cross-pollination (CP) and predicted the CP rate in the field considering and not considering FB. Three experiments including 0, 6.75, and 7.5 m width of the FB respectively were conducted to investigate the effect of distance and the FB on the CP rate. The dispersal models combined kernel and observation model by calculating the parameter of observation model from the output of kernel. These models were employed to predict the CP rate at different distances. The Bayesian method was used to estimate parameters and provided a good prediction with uncertainty. The highest average CP rates in the field with and without FB were 74.29% and 36.12%, respectively. It was found that two dispersal models with the FB effect displayed a higher ability to predict average CP rates. The correlation coefficients between actual CP rates and CP rates predicted by the dispersal model combined zero-inflated Poisson observation model with compound exponential kernel and modified Cauchy kernel were 0.834 and 0.833, respectively. Furthermore, the predictive uncertainty was reducing using the dispersal models with the FB effect. [ABSTRACT FROM AUTHOR]

Background: Flower longevity is closely related to pollen dispersal and reproductive success in all plants, as well as the commercial value of ornamental plants. Mutants that display variation in flower longevity are useful tools for understanding the mechanisms underlying this trait. Heavy-ion beam irradiation has great potential to improve flower shapes and colors; however, few studies are available on the mutation of flower senescence in leguminous plants. Results: A mutant (C416) exhibiting blossom duration eight times longer than that of the wild type (WT) was isolated in Lotus japonicus derived from carbon ion beam irradiation. Genetic assays supported that the delayed flower senescence of C416 was a dominant trait controlled by a single gene, which was located between 4,616,611 Mb and 5,331,876 Mb on chromosome III. By using a sorting strategy of multi-sample parallel genome sequencing, candidate genes were narrowed to the gene CUFF.40834, which exhibited high identity to ethylene receptor 1 in other model plants. A physiological assay demonstrated that C416 was insensitive to ethylene precursor. Furthermore, the dynamic changes of phytohormone regulatory network in petals at different developmental stages was compared by using RNA-seq. In brief, the ethylene, jasmonic acid (JA), and salicylic acid (SA) signaling pathways were negatively regulated in C416, whereas the brassinosteroid (BR) and cytokinin signaling pathways were positively regulated, and auxin exhibited dual effects on flower senescence in Lotus japonicus. The abscisic acid (ABA) signaling pathway is positively regulated in C416. Conclusion: So far, C416 might be the first reported mutant carrying a mutation in an endogenous ethylene-related gene in Lotus japonicus, rather than through the introduction of exogenous genes by transgenic techniques. A schematic of the flower senescence of Lotus japonicus from the perspective of the phytohormone regulatory network was provided based on transcriptome profiling of petals at different developmental stages. This study is informative for elucidating the molecular mechanism of delayed flower senescence in C416, and lays a foundation for candidate flower senescence gene identification in Lotus japonicus. It also provides another perspective for the improvement of flower longevity in legume plants by heavy-ion beam. [ABSTRACT FROM AUTHOR]

Pollen and non-pollen palynomorphs were analysed from 35 modern moss cushions collected along an altitudinal gradient (2225–2552 m a.s.l.) from the Baramulla District of Jammu and Kashmir State (Western Himalaya), India. The selected sampling altitude is at the elevation of appearance of blue pine (Pinus wallichiana) and West Himalayan spruce or morinda spruce (Picea smithiana). We used cluster analysis and principal component analysis (PCA) to reveal trends and characteristics in the modern pollen and non-pollen palynomorph composition within this zone. Tree taxa mainly correlated positively with the altitudinal gradient, i.e. tree pollen is more abundant at higher altitudes. The presence of West Himalayan spruce pollen increased significantly above 2490 m a.s.l., which coincides with its increased abundance in the area. Poaceae, Cerealia, Ranunculaceae, Caryophyllaceae, Asteroideae and Cichorioideae, indicating open land and human agricultural activities, are more characteristic of higher locations. Greater relative abundance of dung spores was characteristic of lower elevations, indicating human-related grazing activities. While tropical deciduous plants grow only at lower elevations away from the study area, their pollen was present at higher altitudes, suggesting long-distance pollen dispersal, beyond the growing localities. [ABSTRACT FROM AUTHOR]

Airborne pollen is indicative of vegetation and climatic conditions. This study investigates airborne pollen trapping in the Betula microphylla-dominated wetland of Ebinur Lake in Northwestern China from September 2012 to August 2015 using Pearson correlation analysis and the Hybrid Single-particle Lagrangian Integrated Trajectory model. Higher temperatures and moderate precipitation during the flowering period facilitated an increase in birch pollen with more exotic spruce pollen carried from the Tianshan Mountains by airflows, leading to the highest arbor pollen concentrations from September 2012 to August 2013. Peak pollen concentrations from September 2013 to August 2014 were possibly due to an increase in herbaceous pollen resulting from higher temperatures, lower precipitation and more exotic pollen from the desert of southwest Ebinur Lake and Central Asia in summer and autumn. Between September 2014 and August 2015, unfavorable climate conditions in summer and autumn decreased the pollen dispersal of xerophytes such as Artemisia and Chenopodiaceae, with little pollen transported from the Kazakh hilly area in late summer, resulting in the lowest pollen concentrations. Climatic parameters and air mass movements both greatly affected the atmospheric pollen concentration. The results provide information concerning the dispersion and distribution of birch pollen, paleoenvironmental reconstruction and wetland conservation. [ABSTRACT FROM AUTHOR]

Evolutionary transitions from animal to wind pollination have occurred repeatedly during the history of the angiosperms, but the selective mechanisms remain elusive. Here, we propose that knowledge of pollen release biomechanics is critical for understanding the ecological and evolutionary processes underpinning this shift in pollination mode. Pollen release is the critical first stage of wind pollination (anemophily) and stamen properties are therefore likely to be under strong selection early in the transition. We describe current understanding of pollen release biomechanics to provide insights on the phenotypic and ecological drivers of wind pollination. Pollen release occurs when detachment forces dominate resistive forces retaining pollen within anthers. Detachment forces can be active or passive depending on whether they require energy input from the environment. Passive release is more widespread in anemophilous species and involves processes driven by steady or unsteady aerodynamic forces or turbulence‐induced vibrations that shake pollen from anthers. We review empirical and theoretical studies suggesting that stamen vibration is likely to be a key mechanism of pollen release. The vibration response is governed by morphological and biomechanical properties of stamens, which may undergo divergent selection in the presence or absence of pollinators. Resistive forces have rarely been investigated for pollen within anthers, but are probably sensitive to environmental conditions and depend on flower age, varying systematically between animal‐ and wind‐pollinated species. Animal and wind pollination are traditionally viewed as dichotomous alternatives because they are usually associated with strikingly different pollination syndromes. But this perspective has diverted attention from subtler, continuously varying traits which mediate the fluid dynamic process of pollen release. Reinterpreting the flower as a biomechanical entity that responds to fluctuating environmental forces may provide a promising way forward. We conclude by identifying several profitable areas for future research to obtain deeper insight into the evolution of wind pollination. [ABSTRACT FROM AUTHOR]

Temporal changes in the composition and abundance of floral visitors during floral anthesis influence the rate of deposition and germination of pollen in stigmas, as well as the rate of removal of pollen from anthers. In the tropics, the squash (Cucurbita pepo) is visited by a great diversity of bees, but little is known regarding the dynamics of its pollinators and pollination during its floral anthesis in tropical environments. We studied the foraging cycle of different species of bees in squash crops in Costa Rica and the relationship of this cycle with nectar production, pollen loads in anthers and bees, and number of pollen grains and pollen tubes in stigmas and styles. It was determined that despite the short duration of the floral anthesis of this crop, there are changes in the composition of visitors during anthesis from bees with twilight flight capacity that visit male flowers in the opening to primarily social bees at later hours. Loss of pollen from anthers and deposition of pollen on stigmas occurs rapidly in early hours. Pollen transport by bees may be facilitated by pollen accumulation at the bottom of the corolla of male flowers. After 6 a.m., little change occurs in crop pollination levels. The dominance of stingless bees in the flowers after 6:30 a.m. appears to displace other bees from these flowers, despite the permanence of nectar flow. The Cucurbita species may be an important crop for maintaining bee diversity and enhancing the pollination of other crops in agricultural ecosystems. [ABSTRACT FROM AUTHOR]

Abstract Background So far, little is known in detail about mating systems of woody bamboos. Paternity analysis of offspring improved our understanding of these systems, and contributed to their germplasm conservation and genetic improvement. Results In this study, a paternity analysis of offspring from two consecutive mass or sporadically flowering events of Dendrocalamus membranaceus and D. sinicus were conducted to determine their mating system and pollen dispersal using the program COLONY based on simple sequence repeat (SSR) markers. Two sporadically flowering populations of D. sinicus (C1, C2) obtained relatively high paternity assignments rates (69.0–71.4%). Meanwhile, among three populations of D. membranaceus, the sporadically flowering population A also had much higher paternity assignments rates (56.4%) than mass flowering populations B1(28.6%) and B2 (42.5%). Both D. membranaceus and D. sinicus had mixed mating systems while their mating patterns were variable depending on pollination conditions. The maximum pollen dispersal distances were 90 m and 4378 m for D. membranaceus and D. sinicus populations, respectively, and the mating distances of these two species focused on ranges of ca. 0–50 m and 0–1500 m, respectively. Conclusions These results revealed for the first time variable mating patterns in woody bamboos. This suggests half-sib seeds from the same bamboo clump may have different male parents and it is crucial to clarify genetic origin in woody bamboos’ breeding programs. The results also indicate the importance of pollinators in the mating systems of tropical woody bamboos.

Abstract The main selective force driving floral evolution and diversity is plant–pollinator interactions. Pollinators use floral signals and indirect cues to assess flower reward, and the ensuing flower choice has major implications for plant fitness. While many pollinator behaviors have been described, the impact of parasites on pollinator foraging decisions and plant–pollinator interactions have been largely overlooked. Growing evidence of the transmission of parasites through the shared‐use of flowers by pollinators demonstrate the importance of behavioral immunity (altered behaviors that enhance parasite resistance) to pollinator health. During foraging bouts, pollinators can protect themselves against parasites through self‐medication, disease avoidance, and grooming. Recent studies have documented immune behaviors in foraging pollinators, as well as the impacts of such behaviors on flower visitation. Because pollinator parasites can affect flower choice and pollen dispersal, they may ultimately impact flower fitness. Here, we discuss how pollinator immune behaviors and floral traits may affect the presence and transmission of pollinator parasites, as well as how pollinator parasites, through these immune behaviors, can impact plant–pollinator interactions. We further discuss how pollinator immune behaviors can impact plant fitness, and how floral traits may adapt to optimize plant fitness in response to pollinator parasites. We propose future research directions to assess the role of pollinator parasites in plant–pollinator interactions and evolution, and we propose better integration of the role of pollinator parasites into research related to pollinator optimal foraging theory, floral diversity and agricultural practices.

Gene flow studies provide information on gene exchange between populations, which is essential for developing genetic conservation strategies. Such analyses enable a better understanding of the life history and seed and pollen dispersal mechanisms of plant species. In this study, we investigate pollen and seed flow in a regenerant population of the pioneer species Astronium fraxinifolium in an area degraded during the construction of a hydroelectric dam. We mapped, sampled, sexed, and genotyped 386 individuals in the regenerant population (RP), as well as 128 adult trees located along two highways adjacent to the degraded area; one in Mato Grosso do Sul State (MS) and other in São Paulo State (SP). Parentage analyses was carried out for 370 individuals of the RP population, using as putative parents 348 individuals from RP and all 128 individuals sampled in MS and SP. Based on parentage analysis and eight microsatellite loci, our analyses revealed that for individuals of the RP with an identified father (pollen donor), 1.1% of the pollen was dispersed up to 532 m, while for those with an identified mother (seed donor), 0.5% of seeds were dispersed up to 4,782 m. However, a large proportion of pollen (76.5%) and seeds (57%) immigrated from trees outside the sampled populations. Pollen and seeds were dispersed through a pattern of isolation by distance. Genetic diversity was significantly similar between adults of both highway populations and individuals from RP, with significant levels of inbreeding detected only in RP. Our results demonstrate that the nearest trees contributed pollen and seeds for the recovery of the degraded area, indicating reproductive spatial isolation among the sampled populations due to the damming of the river. Such results help to understand the process of regeneration for A. fraxinifolium in regenerant populations to inform strategies for conservation and environmental recovery with this species. [ABSTRACT FROM AUTHOR]

Our knowledge of the impact of landscape fragmentation on gene flow patterns is mainly drawn from tropical and temperate ecosystems, where landscape features, such as the distance of a tree to the forest edge, drive connectivity and mating patterns. Yet, the structure of arid and semiarid plant communities – with open canopies and a scattered distribution of trees – differs greatly from those that are well‐characterized in the literature. As a result, we ignore whether the documented consequences of landscape fragmentation on plant mating and gene flow patterns also hold for native plant communities in arid and semiarid regions. We investigated the relative contribution of plant traits, pollinator activity, and individual neighbourhood in explaining variation in mating and gene flow patterns of an insect‐pollinated semiarid arborescent shrub, Ziziphus lotus, at three sites embedded in highly altered agriculture landscapes. We used 14 SSRs, seed paternity analyses, and individual mixed effect mating models (MEMMi) to estimate the individual mating variables and the pollen dispersal kernel at each site. Individual spatial location, flower density, and floral visitation rate explained most of the variation of mating variables. Unexpectedly, individual correlated paternity was very low and shrubs surrounded by the most degraded matrix exhibited an increased fraction of pollen immigration and a high effective number of pollen donors per mother shrub. Overall, our results reveal that an active pollinator assemblage ensures highly efficient mating, and maintains pollen‐mediated gene flow and notable connectivity levels, even in highly altered landscapes, potentially halting genetic isolation within and between distant sites. [ABSTRACT FROM AUTHOR]

To understand the resilience of African savannas to global change, quantitative information on the long-term dynamics of vegetation is required. Past dynamics can be reconstructed with the REVEALS model, which requires pollen productivity estimates (PPE) that are calibrated using surface pollen and vegetation data. Here we calculated PPE values for five savanna taxa using the extended R-value (ERV) model and two pollen dispersal options: the Gaussian plume model (GPM) and the Lagrangian stochastic model (LSM). The ERV calculations failed to produce a reliable PPE for Poaceae. We therefore used Combretaceae as the reference taxon – although values obtained with Poaceae as the reference taxon are presented in the supplement. Our results indicate that Combretaceae is the taxon with the highest pollen productivity and Grewia the taxon with the lowest productivity. Acacia and Dichrostachy s are intermediate pollen producers. We find no clear indication of whether the GPM PPEs or the LSM PPEs are more realistic, but the differences between these values confirmed that the pollen fall speed has a greater effect in the modelling of GPM than in the LSM. We also applied REVEALS to the pollen record of Lake Otjikoto (northern Namibia) and obtained the first quantitative reconstruction of the last 130 years of vegetation history in the region. Cover estimates for Poaceae indicate the predominance of a semi-open landscape throughout the 20th century, while cover values below 50% since the 21st century correspond to a thick savanna. This change in grass cover is associated with the spread of Vachellia, Senegalia and Grewia reflecting an encroached state. [ABSTRACT FROM AUTHOR]

Prevailing directions of seed and pollen dispersal may induce anisotropy of the fine‐scale spatial genetic structure (FSGS), particularly in wind‐dispersed and wind‐pollinated species. To examine the separate effects of directional seed and pollen dispersal on FSGS, we conducted a population genetics study for a dioecious, wind‐pollinated, and wind‐dispersed tree species, Cercidiphyllum japonicum Sieb. et Zucc, based on genotypes at five microsatellite loci of 281 adults of a population distributed over a ca. 80 ha along a stream and 755 current‐year seedlings. A neighborhood model approach with exponential‐power‐von Mises functions indicated shorter seed dispersal (mean = 69.1 m) and much longer pollen dispersal (mean = 870.6 m), effects of dispersal directions on the frequencies of seed and pollen dispersal, and the directions with most frequent seed and pollen dispersal (prevailing directions). Furthermore, the distance of effective seed dispersal within the population was estimated to depend on the dispersal direction and be longest at the direction near the prevailing direction. Therefore, patterns of seed and pollen dispersal may be affected by effective wind directions during the period of respective dispersals. Isotropic FSGS and spatial sibling structure analyses indicated a significant FSGS among the seedlings generated by the limited seed dispersal, but anisotropic analysis for the seedlings indicated that the strength of the FSGS varied with directions between individuals and was weakest at a direction near the directions of the most frequent and longest seed dispersal but far from the prevailing direction of pollen dispersal. These results suggest that frequent and long‐distance seed dispersal around the prevailing direction weakens the FSGS around the prevailing direction. Therefore, spatially limited but directional seed dispersal would determine the existence and direction of FSGS among the seedlings. [ABSTRACT FROM AUTHOR]

Premise: Pollinator foraging behavior can influence pollen dispersal and gene flow. In many plant species a pollinator trips a flower by applying pressure to release its sexual organs. We propose that differences in tripping rate among grooming pollinators could generate distinct pollen deposition curves, the pattern of pollen deposition over successive flowers visited. This study compares the pollen deposition curves of two grooming pollinators, a social bumble bee and a solitary leafcutting bee, with distinct tripping rates on Medicago sativa flowers. We predict a steeper deposition curve for pollen moved by leafcutting bees, the pollinator with the higher tripping rate. Methods: Medicago sativa plants carrying a gene (GUS) whose product is easily detected by staining, were used as pollen donors. After visiting the GUS plants, a bee was released on a linear array of conventional M. sativa plants. The number of GUS pollen grains deposited over successive flowers visited or over cumulative distances was examined. Distinct mixed effect Poisson regression models, illustrating different rates of decay in pollen deposition, were fitted to the pollen data for each bee species. Results: Pollen decay was steeper for leafcutting bees relative to bumble bees for both models of flowers visited and cumulative distance, as predicted by their higher tripping rate. Conclusions: This is the first report of a difference in pollen deposition curves between two bee species, both grooming pollinators. Such differences could lead to distinct impacts of bee species on gene flow, genetic differentiation, introgression, and ultimately speciation. [ABSTRACT FROM AUTHOR]

An understanding of the relationship between modern pollen and vegetation is a prerequisite for reconstruction of vegetation and climate change from fossil pollen records. We conducted palynological studies of thirty-five surface soil samples from the Jammu region of India, which revealed that Pinus, among the conifers (regional needle-leaved taxa), is over-represented in the pollen assemblage due to its high production and effective dispersal of pollen. Other coniferous and broadleaved (regional and/or extra-regional) taxa have comparatively lower values in the pollen assemblages, similar to the representation of subtropical deciduous forest elements (regional), as well as shrubby (regional and/or extra-regional) taxa. This inconsistency in the pollen assemblage could be due to long-distance transport of the former by wind and/or water from the higher reaches of the Himalayas, and also because the latter have an entomogamous pollination syndrome and are not high pollen producers. The recovered pollen assemblage presents a distorted picture of the extant vegetation; hence, caution should be exercised in interpreting fossil pollen records from the study area. Principal component analysis (PCA) shows variability in the distribution of pollen from different sites in the Jammu region, perhaps the result of transport (by wind and/or water), altitude and/or edaphic factors of the Himalayan terrain. The study should improve our understanding of the modern pollen-vegetation relationship and aid further calibration and interpretation of fossil pollen records. [ABSTRACT FROM AUTHOR]

This study highlights the modern pollen-vegetation relationships along an altitudinal gradient covering the lower temperate (∼2,000 masl) to alpine vegetation zones (∼3,800 masl) in the Bhagirathi valley, western Himalaya. The pollen dispersal dataset compared with the altitudinal vegetation distribution in the valley shows incoherency between the arboreal taxa and their respective pollen proportions. Discriminant analysis (DA) revealed the role of diurnal valley winds in pollen mixing between altitudinal vegetation zones. Pollen of arboreal taxa are transported profusely from the lower temperate vegetation zones to alpine zone. Whereas pollen of non-arboreal taxa, dominantly growing in the sub-alpine and alpine meadows, remain close to their source and represent the prevailing localized environmental conditions in the valley. Study revealed Pinus and Quercus as dominant arboreal pollen taxa throughout the altitudinal transect with a distinct transition in their representation between ∼2,500 and 2,600 masl. High percentage of Pinus (Quercus) pollen below (above) this transition zone nearly corresponds with the present distribution of conifer (pine-oak) and broadleaved (oak-pine) forests in the valley and can be taken as a marker zone to infer palaeoecological changes. The sub-alpine and alpine krummholz, Juniperus and Ericaceae are found autochthonous in their pollen distribution that can serve as good indicators of relative tree-line and glacier dynamics in past. This pollen-vegetation relationship dataset could be an analogue for the interpretation of fossil pollen records in terms of extant vegetation in the mountain regions. [ABSTRACT FROM AUTHOR]

Gene flow may occur both through pollen movement and seed dispersal, although their relative contribution to overall species gene flow is not understood for most tropical trees, which compromises management recommendations. We investigated the implications of seed dispersal limitation, pollen dispersal capacity, and mating system to the spatial genetic structure of populations of the Neotropical legume tree, Centrolobium tomentosum, in Brazil's Atlantic Forest. We estimated seed dispersal distribution by counting individuals around adult trees; pollen dispersal distribution and outcrossing rates from adult and offspring genotypes, using seven microsatellite loci. Spatial genetic structure was inferred through the correlation among kinship coefficients and geographical distances between pairs of individuals, using nuclear and chloroplast microsatellite markers. We observed restricted seed dispersal, with most seeds (78%) falling up to 10 m from the adult tree trunk. The best-fitted pollen dispersal distribution was the exponential power distribution, with a heavy tail and average pollen dispersal distance of 3191 m. The mating system was preferably allogamous, with an average of eight pollen donors. There was significant spatial genetic structure in all populations, with stronger structure obtained from chloroplast DNA, which suggests that the restricted gene flow by seed dispersal may be compensated by high outcrossing rates and long-distance pollen flow promoted by the large bees that pollinate the species. Our results emphasize the importance of pollination services in fragmented tropical landscapes, where most tree species are pollinated by animals and a large number of species experience seed dispersal limitation. [ABSTRACT FROM AUTHOR]

Aims The evolution and expression of dispersal-related traits are intertwined with those of other life-history functions and are manifested within various physiological constraints. Such a relationship is predicted between inbreeding levels and dispersability, which may be anatomically and ontogenetically linked so that the selection pressures on one may affect the other. While both the effect of inbreeding on reproductive success and on dispersal strategies received much attention, only a few studies considered both simultaneously. Furthermore, such studies often rely on two dichotomic representations of breeding and dispersal: using selfing versus outcrossing as a representation of breeding level, and dispersal ratio as the sole representation of dispersal strategy. Methods Here, we used pollination experiments in the heterocarpic Crepis sancta (Asteraceae) to expand in two different manners on the common practice of using dichotomic representations of breeding and dispersal. First, we used pollination treatments that represent a continuum from selfing through pollination by kin to pollination by a distant neighbor. Second, we measured a whole set of continuous morphological and dispersal-related traits, in addition to measurements of reproductive success and dispersal ratio. Important Findings The proportion of developed capitula and the number of both dispersed and non-dispersed achenes were significantly lower in the self-pollination treatment in comparison to the outcrossed treatments. The effect of pollen sources on dispersal ratio was not statistically significant, though self-pollinated plants rarely produced non-dispersing seeds. Achene's biomass increased with distance between parent plants, but pappus width did not, leading to a nonsignificant effect of pollination on falling velocity. Overall, pollen source affected mainly traits that were associated with reproductive output, but it had no clear effect on predominately dispersal-related traits. Such differences in the response of reproduction and dispersal traits to variation in pollen source suggest that dispersal-related selection is probably weak and/or masked by other forces. [ABSTRACT FROM AUTHOR]

Seed and pollen dispersal are important for defining sustainable forest management practices. By reducing population density, selective logging could affect not only the seed production of timber species but also the selfing rate and the patterns of seed and pollen rains. To assess these risks, we characterized seed and pollen dispersal patterns and the fine-scale spatial genetic structure (FSGS) of Pericopsis elata, a gregarious, wind-dispersed legume tree which is highly logged in Central Africa and threatened by overexploitation. Eleven microsatellite markers were used to genotype 189 adults and 664 seedlings in a 4 km2 plot in the Democratic Republic of Congo (DRC). According to the neighbourhood model, seed dispersal was extremely leptokurtic, with 80% of seeds dispersal distances <75 m, 15% >500 m. Pollen dispersal was locally more extensive (median distance 260 m), but pollen immigration was not detected, and the selfing rate (54%) appeared particularly high compared to other tropical tree species. Limited gene dispersal resulted in remarkably high FSGS (Sp = 0.072). A decay of inbreeding with age also suggests that the species is prone to inbreeding depression. The reproductive success of trees was positively related to their diameter at breast height (dbh), with half of the progeny mothered by trees with dbh > 97 cm and fathered by trees with dbh > 119 cm. Our study highlights that (1) seed sources must be diversified for plantation or population reinforcement to limit consanguinity, and (2) the legal minimum cutting diameter in DRC (60 cm) should be increased to maintain enough post-logging reproductive potential. [ABSTRACT FROM AUTHOR]

Exploring the effects of orographic events and climatic shifts on the geographic distribution of organisms in the Himalayas-Hengduan Mountains (HHM) region and Qinghai-Tibetan Plateau (QTP) is crucial to understand the impact of environmental changes on organism evolution. To gain further insight into these processes, we reconstructed the evolutionary history of nine Chamaesium species distributed across the HHM and QTP regions. In total, 525 individuals from 56 populations of the nine species were analyzed based on three maternally inherited chloroplast fragments (rpl16 , trnT-trnL , and trnQ-rps16) and one nuclear DNA region (internal transcribed spacer, ITS). Fifty-two chloroplast DNA (cpDNA) and 47 ITS haplotypes were identified in nine species. All of the cpDNA and ITS haplotypes were species-specific. Phylogenetic analysis suggested that all nine species form a monophyletic clade with high support. Dating analysis and ancestral area reconstruction revealed that the ancestral group of Chamaesium originated in the southern Himalayan region at the beginning of the Paleogene (60.85 Ma). The nine species of Chamaesium then separated well during the last 25 million years started in Miocene. Our maxent modeling indicated the broad-scale distributions of all nine species remained fairly stable from LIG to the present and predicted that it will remain stable into the future. The initial split of Chamaesium was triggered by climate changes following the collision of the Indian plate with the Eurasia plate during the Eocene. Subsequently, divergences within Chamaesium may have been induced by the intense uplift of the QTP, the onset of the monsoon system, and Central Asian aridification. Long evolutionary history, sexual reproduction, and habitat fragmentation could contribute to the high level of genetic diversity of Chamaesium. The higher genetic differentiation among Chamaesium populations may be related to the drastic changes of the external environment in this region and limited seed/pollen dispersal capacity. [ABSTRACT FROM AUTHOR]

Gene flow from an experimental plot of genetically modified eucalypt was studied by measuring pollen dispersal at various distances from the pollen donor up to a maximum distance of 1592 m. Spontaneous seedling establishment around mother trees, the potential receptors of GM pollen, was also verified. All trees analyzed in this study were identified as compatible for crossing with the pollen donor and their flowering time frame showed at least two weeks synchronism with GM pollen donors. As reported in previous studies, pollination occurred at short distances then declined rapidly within 200 m. The results obtained are consistent with data from other reports in different conditions. In the current study, only two GM seedlings out of 574 were detected at distances greater than 300 m from source (one at 400 and the other at 857 m), in rates varying from zero to 1.5% until 857 m, and null above this. Although effective GM crossings were found in compatible trees around the pollen donors, no spontaneous seedling establishment was observed. [ABSTRACT FROM AUTHOR]

Orchids differ from other plants in their extremely small and partly air‐filled seeds that can be transported long distances by wind. Seed dispersal in orchids is expected to contribute strongly to overall gene flow, and orchids generally express low levels of genetic differentiation between populations and low pollen to seed flow ratios. However, studies in orchids distributed in northern Europe have often found a poor geographic structuring of genetic variation. Here, we studied geographic differentiation in the marsh orchid Dactylorhiza umbrosa, which is widely distributed in upland regions from Asia Minor to Central Asia. These areas were less affected by Pleistocene ice ages than northern Europe and the orchid should have been able to survive the last ice age in local refugia. In the plastid genome, which is dispersed by seeds, populations at close distance were clearly divergent, but the differentiation still increased with geographic distance, and a significant phylogeographic structure had developed. In the nuclear genome, which is dispersed by both seeds and pollen, populations showed an even stronger correlation between genetic and geographic distance, but average levels of differentiation were lower than in the plastid genome, and no phylogeographic structure was evident. Combining plastid and nuclear data, we found that the ratio of pollen to seed dispersal (mp/ms) decreases with physical distance. Comparison with orchids that grow in parts of Europe that were glaciated during the last ice suggests that a balanced structure of genetic diversity develops only slowly in many terrestrial orchids, despite efficient seed dispersal. [ABSTRACT FROM AUTHOR]

Premise: The genetic structure between plant populations is facilitated by the spatial population arrangement and limited dispersal of seed and pollen. Saxifraga acerifolia, a local endemic species in Japan, is a habitat specialist that is confined to waterfalls in riparian environments. Its sister species, Saxifraga fortunei, is a generalist that is widely distributed along riverbanks. Here, we examined sympatric populations of the two Saxifraga species to test whether the differences in habitat preference and colonization process influenced regional and local genetic structures. Methods: To reveal genetic structures, we examined chloroplast microsatellite variations and genome‐wide nucleotide polymorphisms obtained by genotyping by sequencing. We also estimated the gene flow among and within populations and performed landscape genetic analyses to evaluate seed and pollen movement and the extent of genetic isolation related to geographic distance and/or habitat differences. Results: We found strong genetic structure in the specialist S. acerifolia, even on a small spatial scale (<1 km part); each population on a different waterfall in one river system had a completely different predominant haplotype. By contrast, the generalist S. fortunei showed no clear genetic differentiation. Conclusions: Our findings suggest that the level of genetic isolation was increased in S. acerifolia by the spatially fragmented habitat and limited seed and pollen dispersal over waterfalls. Habitat differentiation between the sister taxa could have contributed to the different patterns of gene flow and then shaped the contrasting genetic structures. [ABSTRACT FROM AUTHOR]

Fragmented landscapes may have implications for the genetic structure of populations and for the microevolution of plant species. In particular, landscape fragmentation and/or population isolation might affect the evolution of plant mating systems. Here, we study the consequences of landscape fragmentation on the genetic structure of populations of a perennial herb, Vincetoxicum hirundinaria with a mixed mating system. Our study area, the south‐western Finnish archipelago, was formed after the glacial ice sheet started to retreat 12 000 years ago. Due to the isostatic land uplift following the glacial retreat, suitable habitats have been formed gradually, and as a consequence, populations of V. hirundinaria differ in age, size and their degree of isolation in the area. We hypothesized that a mixed‐mating system has been selected for in these populations due to the advantage of self‐fertilization in newly colonized areas and the advantage of outcrossing in adaptation to heterogeneous environments. To test this hypothesis, we collected seeds of open‐pollinated flowers from 13 V. hirundinaria populations differing in size, age and isolation, and used 15 microsatellite markers to perform progeny‐array analysis to estimate population‐level outcrossing rates, population genetic indices and population structure. We found that V. hirundinaria is almost completely outcrossing in the study area with no signs of past self‐fertilization and/or mating among relatives. The overall low inbreeding coefficients indicate that even in small populations mating among relatives is rare. High allelic richness of both maternal and offspring genotypes as well as limited genetic differentiation among the studied populations indicate strong gene flow among them. Our findings suggest that V. hirundinaria has successful seed and pollen dispersal among populations that has allowed colonization of new habitats in this fragmented landscape and led to a genetically well‐mixed group of populations at the scale of the study. [ABSTRACT FROM AUTHOR]

Individual differences in male reproductive success drive genetic drift and natural selection, altering genetic variation and phenotypic trait distributions in future generations. Therefore, identifying the determinants of reproductive success is important for understanding the ecology and evolution of plants. Here, based on the spatially explicit mating model (the neighborhood model), we develop a hierarchical probability model that links co‐dominant genotypes of offspring and candidate parents with phenotypic determinants of male reproductive success. The model accounts for pollen dispersal, genotyping errors as well as individual variation in selfing, pollen immigration, and differentiation of immigrant pollen pools. Unlike the classic neighborhood model approach, our approach is specially designed to account for excessive variation (overdispersion) in male fecundity. We implemented a Bayesian estimation method (the Windows computer program available at: https://www.ukw.edu.pl/pracownicy/plik/igor%5fchybicki/1806/) that, among others, allows for selecting phenotypic variables important for male fecundity and assessing the fraction of variance in fecundity (R2) explained by selected variables. Simulations showed that our method outperforms both the classic neighborhood model and the two‐step approach, where fecundities and the effects of phenotypic variables are estimated separately. The analysis of two data examples showed that in wind‐pollinated trees, male fecundity depends on both the amount of produced pollen and the ability to pollen spread. However, despite that the tree size was positively correlated with male fecundity, it explained only a fraction of the total variance in fecundity, indicating the presence of additional factors. Finally, case studies highlighted the importance of accounting for pollen dispersal in the estimation of fecundity determinants. [ABSTRACT FROM AUTHOR]

Hybrid zones between species with staggered reproductive phenology sometimes occur along elevational gradients. The maintenance of such hybrid zones may depend on elevational shift in phenology and vertical dispersal of pollen and seeds. In a hybrid zone of Cerasus leveilleana (Cl) and C. sargentii (Cs), 111 adults, 372 embryos of 65 mothers, and 133 juveniles were sampled across elevations of 900–1,400 m in central Japan. Using the hybrid index estimated from nuclear microsatellites, the samples were assigned to Cl, Cs or their hybrid taxon. Cs was in higher elevations than Cl with an overlapping range, and their hybrids were in intermediary elevations. Flowering periods were earlier in Cs than in Cl with little overlap at the same elevation and were intermediate in their hybrids. Flowering periods were delayed in higher elevations and overlapped between Cl and Cs in different elevations. Fruiting periods were slightly earlier in Cs than in Cl but were largely overlapped. Effective pollinators and seed dispersers were common among the taxa. Changes in the hybrid index from mothers to their embryos were larger in hybrid mothers than in Cl or Cs mothers, indicating mating of hybrids with diverse taxa. In Cs, juveniles were more abundant in lower elevations than embryos, indicating downhill seed dispersal. Proportions of hybrids were 19% in embryos, 17% in juveniles and 12% in adults. The findings suggest that the hybrid zone is maintained by interspecific pollination between different elevations, backcrossing with hybrids at similar elevations, vertical seed dispersal and mild selection against hybrids. [ABSTRACT FROM AUTHOR]

Sexual dimorphism in plants may emerge as a result of sex‐specific selection on traits enhancing access to nutritive resources and/or to sexual partners. Here we investigated sex‐specific differences in selection of sexually dimorphic traits and in the spatial distribution of effective fecundity (our fitness proxy) in a highly dimorphic dioecious wind‐pollinated shrub, Leucadendron rubrum. In particular, we tested for the effect of density on male and female effective fecundity. We used spatial and genotypic data of parent and offspring cohorts to jointly estimate individual male and female effective fecundity on the one hand and pollen and seed dispersal kernels on the other hand. This methodology was adapted to the case of dioecious species. Explicitly modelling dispersal avoids the confounding effects of heterogeneous spatial distribution of mates and sampled seedlings on the estimation of effective fecundity. We also estimated selection gradients on plant traits while modelling sex‐specific spatial autocorrelation in fecundity. Males exhibited spatial autocorrelation in effective fecundity at a smaller scale than females. A higher local density of plants was associated with lower effective fecundity in males but was not related to female effective fecundity. These results suggest sex‐specific sensitivities to environmental heterogeneity in L. rubrum. Despite these sexual differences, we found directional selection for wider canopies and smaller leaves in both sexes, and no sexually antagonistic selection on strongly dimorphic traits in L. rubrum. Many empirical studies in animals similarly failed to detect sexually antagonistic selection in species expressing strong sexual dimorphism, and we discuss reasons explaining this common pattern. [ABSTRACT FROM AUTHOR]

The genetic structure of a population can provide important insights into animal movements at varying geographical scales. Individual and social behaviors, such as philopatry and dispersal, affect patterns of relatedness, age and sex structure, shaping the local genetic structure of populations. However, these fine scale patterns may not be detected within broader population genetic structure. Using SNP genotyping for pairwise relatedness estimates, we investigated the spatial and genetic structuring of 141 red foxes within south-central Sweden at two scales. First, we looked at broad scale population structuring among red foxes at the regional level. We then estimated pairwise relatedness values to evaluate the spatial and genetic structure of male, female and mixed sex pairs for patterns of philopatry and dispersal at a more localized scale. We found limited genetic differentiation at the regional scale. However, local investigations revealed patterns of female philopatry and male biased dispersal. There were significant differences in pairwise geographic distances between highly related same sex pairs with the average distance between related males, 37.8 km, being six times farther than that of related females, averaging 6.3 km. In summary, the low levels of genetic differentiation found in this study illustrates the mobility and dispersal ability of red foxes across scales. However, relatedness plays a strong role in the spatial organization of red foxes locally, ultimately contributing to male biased dispersal patterns. [ABSTRACT FROM AUTHOR]

Anadenanthera (Fabaceae) is endemic to the Neotropics and consists of two tree species: A. colubrina (Vell.) Brenan and A. peregrina (L.) Speg. This study examined the mating system and contemporary gene flow of A. colubrina (Acol) and A. peregrina (Aper) in a highly fragmented area of the Atlantic Forest to provide valuable information that informs conservation strategies. Reproductive adults from forest remnants [nA. colubrina = 30 (2.7 ha), nA. peregrina = 55 (4.0 ha)] and progeny-arrays (nA. colubrina = 322, nA. peregrina = 300) were genotyped for seven nuclear microsatellite markers. Mating system analyses revealed that A. colubrina is a mixed mating species (tm = 0.619) while A. peregrina is a predominantly outcrossing species (tm = 0.905). For both Anadenanthera species, high indices of biparental inbreeding were observed (Acol = 0.159, Aper = 0.216), resulting in low effective pollination neighborhood sizes. Categorical paternity analysis revealed different scales of pollen dispersal distance: the majority of crossings occurring locally (i.e., between nearby trees within the same population), with moderate pollen dispersal coming from outside the forest fragments boundaries (Acolmp = 30%, Apermp = 35%). Nevertheless, pollen immigration from trees outside the populations for both species suggests that the populations are not reproductively isolated. This study highlights the importance of evaluating both mating system and contemporary gene flow for a better understanding of the biology of Anadenanthera species. This information should be considered to ensure the effective conservation and management practices of these plant species. [ABSTRACT FROM AUTHOR]

Aims Sexual dimorphism is a common trait in plants with sex separation, which could influence female and male functions differently. In a subdioecious population of Dasiphora glabra on the Qinghai-Tibet Plateau, we investigated sexual dimorphism of floral traits and their effects on pollinator visitation, pollen flow and seed production. We also examined differences in genome size of hermaphroditic and dioecious plants. Methods We examined sexual dimorphism in flower number, flower size, and pollen and ovule production in a subdioecious population of D. glabra. We compared pollinator visitation, pollen dispersal and seed production between sexes. We also examined the genome size of three sex morphs using flow cytometry. Important Findings The number of hermaphroditic plants was significantly more than that of male and female plants, and dioecious plants accounted for ca. 40% in the study population. Hermaphroditic plants produced significantly more flowers than male and female plants. Flower size of male flowers was significantly larger than that of female and hermaphroditic flowers. Male flowers did not produce more pollen grains than hermaphroditic flowers, but female flowers produced more ovules than hermaphroditic flowers. Flies were the most frequent flower visitors and preferred large flowers, but their movements between flowers did not show any preference to large flowers. Simulated pollen flows suggested that effective pollen transfer was generally low for both hermaphroditic and male flowers, corresponding to the low seed set of naturally pollinated flowers. DNA contents of male and female plants were ca. four times than those of hermaphroditic plants. These results suggest male and female individuals have undergone polyploidy events and thus are not compatible with hermaphroditic individuals. Sexual dimorphism in floral traits in relation to pollination of dioecious plants might show an advantage in female and male functions, but this advantage is masked largely by low effectiveness of pollen transfer. [ABSTRACT FROM AUTHOR]

ABSTRACT Pollen is generally dispersed in a sexually immature and somewhat dehydrated, metabolically quiescent state. Yet, in some species, pollen at anthesis is well-hydrated and metabolically active, and in 30 % of angiosperms pollen is dispersed after having formed its sperm cells. Pollen water content and sexual maturity may be correlated, either because both are subject to trade-offs between dispersal viability and post-pollination performance, or because the traits display developmental linkages. We inferred relative water content of sexually immature (“bicellular”) and sexually mature (“tricellular”) pollen of 30 species of angiosperms using a hydration index (HI) that ranges from zero to one, based on how near fresh pollen volume is to its minimal (dehydrated) or maximal (hydrated) volume. Tricellular pollen had 30 % higher HI than bicellular pollen (P < 0.005), after controlling for initial pollen size (larger pollen had higher HI; P < 0.05). A literature survey of 344 species indicated that the tricellular and hydrated states were strongly associated, although all four trait state combinations were present (P < 0.0001). Our results suggest that a common mechanism for the repeated origins of tricellular pollen has been via the loss of controlled pollen dehydration, which enables either accelerated or extended pollen development.

Summary: Pollinators influence patterns of plant speciation, and one intuitive hypothesis is that pollinators affect rates of plant diversification through their effects on pollen dispersal. By specifying mating events and pollen flow across the landscape, distinct types of pollinators may cause different opportunities for allopatric speciation. This pollen dispersal‐dependent speciation hypothesis predicts that pollination mode has effects on the spatial context of mating events that scale up to impact population structure and rates of species formation. Here I consider recent comparative studies, including genetic analyses of plant mating events, population structure and comparative phylogenetic analyses, to examine evidence for this model. These studies suggest that highly mobile pollinators conduct greater gene flow within and among populations, compared to less mobile pollinators. These differences influence patterns of population structure across the landscape. However, the effects of pollination mode on speciation rates is less predictable. In some contexts, the predicted effects of pollen dispersal are outweighed by other factors that govern speciation rates. A multiscale approach to examine effects of pollination mode on plant mating system, population structure and rates of diversification is key to determining the role of pollen dispersal on plant speciation for model clades. [ABSTRACT FROM AUTHOR]

Background: Cleistogamic flowers are a main barrier in pollen dispersal for cross-pollination necessary in wheat hybrid breeding. The aim of our study was to gain new knowledge on the biology of wheat flowering, in particular on the differences between the cleisto- and chasmogamic forms which has certainly cognitive significance, but it can also be used in practice when seeking a female and male ideotypes for cross hybridization. Results: We characterized the most significant features defining the flowering specificity in two wheat cultivars with contrasting tendency to cleistogamy: Piko (chasmogamous) and Dacanto (cleistogamous). In the field observations we assessed diurnal pattern of anther extrusion and anther extrusion capacity. For the first time we adapted the time lapse method for measuring kinetics of the spikelet movement and 3-D image correlation technique for the non-invasive measurements of potential deformations of the spikelet lemmas. We found that the two cultivars differ in the potential of pollen dispersion for-cross-pollination and in the spikelet kinetics. We also described some anatomical traits that can have potential functional role in floret opening. None of the cultivars showed any symptoms of lemma surface deformation. Conclusions: The cleistogamic and chasmogamic wheat cultivars differ significantly in the potential for pollen dispersion for cross-pollination, which is mainly related to anther extrusion capacity. Although none of these features differentiated the cultivars clearly, we assume, based on spikelet kinetics and the lack of lemmas surface deformation, that the water transport and turgor of cells is essential for the floret opening and anther extrusion in wheat. The search for parental ideotype should be supported by marker assisted selection, e.g. based of polymorphisms in genes related to aquaporin biosynthesis. [ABSTRACT FROM AUTHOR]

Ecological genetics can provide a novel contribution to assessing the achievement of restoration objectives. We used paternity assignment to infer realized pollen dispersal within, and pollen immigration into, a restoration population of Hakea nitida, a common near‐coastal shrub or small tree in southwest Australia. We compared mating system parameters and genetic diversity with a nearby remnant reference population and assessed genetic divergence among the restoration and reference populations. We found realized pollen dispersal events closely tracked the frequency distributions of the distances between all plants within the restoration focus area. Mean realized pollen dispersal distance (359 m) approached the mean of the distances between all plants (407 m), far exceeding mean nearest neighbor distance (12 m). Maximum realized pollen dispersal distance (869 m) approached the maximum distance between all plants in the study area (1,033 m). Pollen immigration into the restoration study area was limited (4%). The mating system revealed moderate outcrossing rates (tm = 0.861 restoration and tm = 0.745 reference population), with significant and similar biparental inbreeding (tm − ts = 0.180, tm− ts = 0.186) but greater correlated paternity (rpm) in the restoration (0.519) than in the reference (0.188) population. Genetic divergence among the restoration and reference remnant population was moderate (FST = 0.094, DST = 0.239). Patterns of pollen dispersal and mating system parameters imply the attraction of pollinators within the restoration population as a key factor in progressing towards the establishment of self‐sustaining populations. [ABSTRACT FROM AUTHOR]

Plants are one of the most vulnerable groups to fragmentation and habitat loss, that may affect community richness, abundance, functional traits, and genetic diversity. Here, we address the effects of landscape features on adaptive quantitative traits and evolutionary potential, and on neutral genetic diversity in populations of the Neotropical savanna tree Caryocar brasiliense. We sampled adults and juveniles in 10 savanna remnants within five landscapes. To obtain neutral genetic variation, we genotyped all individuals from each site using nine microsatellite loci. For adaptive traits we measured seed size and mass and grown seeds in nursery in completely randomized experimental design. We obtained mean, additive genetic variance (V a ) and coefficient of variation (CV a %), which measures evolvability, for 17 traits in seedlings. We found that landscapes with higher compositional heterogeneity (SHDI) had lower evolutionary potential (CV a %) in leaf length (LL) and lower aboveground dry mass (ADM) genetic differentiation (Q ST ). We also found that landscapes with higher SHDI had higher genetic diversity (He) and allelic richness (AR) in adults, and lower genetic differentiation (F ST ). In juveniles, SHDI was also positively related to AR. These results are most likely due to longer dispersal distance of pollen in landscapes with lower density of flowering individuals. Agricultural landscapes with low quality mosaic may be more stressful for plant species, due to the lower habitat cover (%), higher cover of monocropping (%) and other land covers, and edge effects. However, in landscapes with higher SHDI with high quality mosaic, forest nearby savanna habitat and the other environments may facilitate the movement or provide additional habitat and resources for seed disperses and pollinators, increasing gene flow and genetic diversity. Finally, despite the very recent agriculture expansion in Central Brazil, we found no time lag in response to habitat loss, because both adults and juveniles were affected by landscape changes. [ABSTRACT FROM AUTHOR]

Using microsatellite loci, we assessed the mating system and genetic diversity of the dioecious tropical tree Genipa americana in a natural population (NP) and a progeny test (PT). For NP, we also estimated the paternity correlation within and among fruits and mean pollen dispersal distance. As expected for dioecious species, all offspring originated from outcrossing (t = 1). Mating among relatives (1 − ts) and paternity correlation (rp) were variable among progenies (1 − ts = 0.03–0.19; rp = 0.04–0.40), but greater in NP than in PT. Fixation index (F) was generally significant and lower in adults than in offspring, indicating selection against inbred individuals. Paternity correlation was higher within (0.40) than among (0.26) fruits, indicating a lower effective number of pollen donors (Nep) within (2.5) than among (3.8) fruits. Due to the higher rp in NP, the effective size within progenies (Ne) was lower (2.69) than PT (3.27). The pollen dispersal pattern was strongly leptokurtic, suggesting long-distance pollen dispersal (mean of 179 m). The results show that both populations can be used for seed collection in environmental reforestation programmes; however, considering that PT is structured in maternal progenies, NP is more suitable for seed collection due to the lower probability of mating among related trees. [ABSTRACT FROM AUTHOR]

Siring success of flowering plants depends on the fates of male gametophytes, which compete for access to stigmas, stylar resources, and ovules. Although rarely considered, pollen may often compete during dispersal, affecting the processes required for export to stigmas: pollen pickup, transport, and deposition. We quantified dispersal interference by tracking bee-mediated dispersal of stained Anacamptis morio (Orchidaceae) pollen from individual donor flowers and inferred the affected dispersal mechanisms on the basis of the fit of a process-based model. During individual trials, all recipient flowers were either emasculated, precluding interference with donor pollen, or intact, adding potentially interfering pollen to the pollinator. The presence of competing pollinaria on bees reduced pickup of additional pollinaria, doubled the overall proportion of lost donor pollen, and reduced total pollen export by 27%. Interference specifically increased loss of donor pollen between successive flower visits and variation in deposition among trials, and it likely also reduced pollen contact with stigmas and pollen deposition when contact occurred. Thus, by altering pollen removal, transport, and deposition, male-male interference during pollen dispersal can significantly—and perhaps commonly—limit plant-siring success. [ABSTRACT FROM AUTHOR]

Most plant species are pollinated by animals, mainly insects, who adjust their foraging behaviour to the spatial distribution of rewards. Any changes in rewards of individual plants could then affect pollen dispersal at the level of plant patches or populations. Such change in floral rewards often results from infection by plant pathogens, for example by anther smuts (i.e. no pollen and reduced nectar in diseased flowers). Here, we tested the hypothesis that the infection of plant populations by anther smuts affects the pattern of pollen dispersal. We investigated the patterns of pollen dispersal in experimental arrays of potted plants differing in the presence of diseased plants and the degree of plant spatial aggregation. We tracked pollen dispersal using a fluorescent dye powder as a pollen analogue, while we simultaneously observed pollinator foraging behaviour. We found that the dispersal of the pollen analogue increased in the presence of diseased plants in experimental arrays, but this effect was strongly dependant on plant spatial aggregation. The parallel observations of pollinator behaviour suggest that this pattern resulted from pollinator discrimination against diseased plants and increased movement in arrays with intermingled diseased plants, provided that plant clusters were close to each other. Our study indicates that pollinators respond to diseased plants in a similar way as to healthy plants with low rewards. Consequently, diseased plants should be treated not only as a potential source of infection but also as a factor influencing pollen dispersal in plant populations. [ABSTRACT FROM AUTHOR]

Sexual reproduction is the primary source of genotypic diversity in seagrass meadows, with important implications for both the evolutionary potential and ecological function of these habitats. However, relatively little is known about seagrass pollination dynamics or how genetic diversity in life history stage may influence genetic diversity in another. We used microsatellite DNA markers to assess how genetic diversity of adult shoots and seeds covaried across the depth gradient in two Zostera marina L. (eelgrass) meadows in Massachusetts (USA). Despite strong spatial patterns in the density of reproductive shoots and genetic evidence for limited pollen dispersal, we found modest corresponding variation in outcrossing rates and paternal diversity. Across spatial scales from quadrats to sites, there was a positive association between the density of flowering shoots and clonal richness; however, other measures of diversity (e.g., allelic richness and heterozygosity) showed weak or opposing patterns with reproductive effort, and neither flowering effort nor local genotypic richness of adults were good proxies for seed diversity. Self-pollinated seeds were significantly smaller than their outcrossed half-siblings, and our data suggest that selection against selfed seeds varies spatially within and among meadows, possibly due to high competition with vegetative shoots in the dense shallow margin. Understanding the processes that shape genetic diversity in seagrass populations is key to their conservation and management; our study highlights the challenges of inferring the contribution of sexual reproduction to population structure using a single metric or life history stage. [ABSTRACT FROM AUTHOR]

An understanding of genetic diversity and the population genetic processes that impact future population viability is vital for the management and recovery of declining populations of threatened species. Styphelia longissima (Ericaceae) is a critically endangered shrub, restricted to a single fragmented population near Eneabba, 250 km north of Perth, Western Australia. For this population, we sought to characterize population genetic variation and its spatial structure, and aspects of the mating portfolio, from which strategies that optimize the conservation of this diversity are identified. A comprehensive survey was carried out and 220 adults, and 106 seedlings from 14 maternal plants, were genotyped using 13 microsatellite markers. Levels of genetic variation and its spatial structure were assessed, and mating system parameters were estimated. Paternity was assigned to the offspring of a subsection of plants, which allowed for the calculation of realized pollen dispersal. Allelic richness and levels of expected heterozygosity were higher than predicted for a small isolated population. Spatial autocorrelation analysis identified fine-scale genetic structure at a scale of 20 m, but no genetic structure was found at larger scales. Mean outcrossing rate (t m = 0.66) reflects self-compatibility and a mixed-mating system. Multiple paternity was low, where 61 % of maternal siblings shared the same sire. Realized pollen dispersal was highly restricted, with 95 % of outcrossing events occurring at 7 m or less, and a mean pollen dispersal distance of 3.8 m. Nearest-neighbour matings were common (55 % of all outcross events), and 97 % of mating events were between the three nearest-neighbours. This study has provided critical baseline data on genetic diversity, mating system and pollen dispersal for future monitoring of S. longissima. Broadly applicable conservation strategies such as implementing a genetic monitoring plan, diluting spatial genetic structure in the natural population, genetically optimizing ex situ collections and incorporating genetic knowledge into translocations will help to manage the future erosion of the high genetic variation detected. [ABSTRACT FROM AUTHOR]

Habitat fragmentation strongly affects the genetic diversity of plant populations, and this has always attracted much research interest. Although numerous studies have investigated the effects of habitat fragmentation on the genetic diversity of plant populations, fewer studies have compared species with contrasting breeding systems while accounting for phylogenetic distance. Here, we compare the levels of genetic diversity and differentiation within and among subpopulations in metapopulations (at fine-scale level) of two closely related Zingiber species, selfing Zingiber corallinum and outcrossing Zingiber nudicarpum. Comparisons of the genetic structure of species from unrelated taxa may be confounded by the effects of correlated ecological traits or/and phylogeny. Thus, we possibly reveal the differences in genetic diversity and spatial distribution of genetic variation within metapopulations that relate to mating systems. Compared to outcrossing Z. nudicarpum , the subpopulation genetic diversity in selfing Z. corallinum was significantly lower, but the metapopulation genetic diversity was not different. Most genetic variation resided among subpopulations in selfing Z. corallinum metapopulations, while a significant portion of variation resided either within or among subpopulations in outcrossing Z. nudicarpum , depending on whether the degree of subpopulation isolation surpasses the dispersal ability of pollen and seed. A stronger spatial genetic structure appeared within subpopulations of selfing Z. corallinum potentially due to restricted pollen flow and seed dispersal. In contrast, a weaker genetic structure was apparent in subpopulations of outcrossing Z. nudicarpum most likely caused by extensive pollen movement. Our study shows that high genetic variation can be maintained within metapopulations of selfing Zingiber species, due to increased genetic differentiation intensified primarily by the stochastic force of genetic drift among subpopulations. Therefore, maintenance of natural variability among subpopulations in fragmented areas is key to conserve the full range of genetic diversity of selfing Zingiber species. For outcrossing Zingiber species, maintenance of large populations is an important factor to enhance genetic diversity. Compared to outcrossing Z. nudicarpum , the subpopulation genetic diversity in selfing Z. corallinum was significantly lower, but the metapopulation genetic diversity did not differ. Most genetic variation resided among subpopulations in selfing Z. corallinum metapopulations, while a significant portion of variation resided either within or among subpopulations in outcrossing Z. nudicarpum , depending on whether the degree of subpopulation isolation surpasses the dispersal ability of pollen and seed. Our study shows that selfing Z. corallinum could maintain high genetic diversity through differentiation intensified primarily by the stochastic force of genetic drift among subpopulations at fine-scale level, but not local adaptation. [ABSTRACT FROM AUTHOR]