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50 results for “pollen dispersal”
Text-fig. 4. Porechye open pit coal mine. a: photography of the Lipovtsy Formation section; b: stratigraphic column, 1 – sandstone, 2 – conglomerate, 3 – coal, 4 – tuff dated by U-Th-Pb geochronology, 5 – siltstone, 6 – mudstone, 7 – palynological samples with angiosperm pollen, 8 – dispersed angiosperm cuticles. in Angiosperm Diversification In The Early Cretaceous Of Primorye, Far East Of Russia
Text-fig. 4. Porechye open pit coal mine. a: photography of the Lipovtsy Formation section; b: stratigraphic column, 1 – sandstone, 2 – conglomerate, 3 – coal, 4 – tuff dated by U-Th-Pb geochronology, 5 – siltstone, 6 – mudstone, 7 – palynological samples with angiosperm pollen, 8 – dispersed angiosperm cuticles.
Mechanisms of male-male interference during dispersal of orchid pollen
<p>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 dispersal of stained <em>Anacamptis morio </em>(Orchidaceae) pollen from individual donor flowers and inferred the affected dispersal mechanisms based on 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 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.</p>
Patterns of pollen dispersal and mating in a population of the clonal plant Sagittaria latifolia
<p>1) Increased plant size is generally expected to have negative consequences for mating by increasing pollen transfer between flowers of the same plant. Such geitonogamous self-pollination would then reduce sexual fitness through both female and male function. However, recent theoretical work has indicated that when plants grow clonally, the outward expansion of plants caused by clonal growth might have positive effects on siring without substantially increasing rates of self-pollination.</p> <p>2) We investigated patterns of pollen dispersal, selfing, and siring in a monoecious population of the clonal plant <em>Sagittaria latifolia</em>, in which clones varied in size and the extent of intermingling with other clones. A spatially-explicit statistical model based on the inferred pollen-dispersal kernel was constructed to examine the mechanisms underlying observed mating patterns.</p> <p>3) Pollen dispersal typically occurred over distances that exceeded the spatial extent of clones. There was a positive association between clone size (measured as the number of ramets per genet) and the likelihood that clones were intermingled with the shoots of other clones. Together, these patterns of pollen dispersal and clonal intermingling resulted in a weak positive association between clone size and selfing rates and a strong positive association between clone size and outcross siring success. These patterns were replicated in the spatially-explicit model, indicating that the intermingling of clones is an important determinant of mating patterns in this population.</p> <p>4) Synthesis. Our study provides the first examination of the pollen dispersal kernel for a clonal plant. It is the first study providing empirical support for model predictions that potentially negative effects of increased selfing in large clones might be offset by increased siring success. This implies that the negative consequences of becoming large do not necessarily apply to clonal plants.</p>
Influence of pollen dispersal and mating pattern in domestication of intermediate Wheatgrass, a novel perennial food crop
<p>Intermediate wheatgrass (IWG) is a perennial forage grass that is currently being domesticated as a grain crop. It is a primarily wind-pollinated outcrossing species and expresses severe inbreeding depression when self-pollinated. Characterization of pollen dispersal, mating parameters, and change in genetic diversity due to pollen movement is currently lacking in IWG. In this study, we examined pollen dispersal in an IWG selection nursery by evaluating 846 progeny from 15 mother plants and traced their parentage to 374 fathers. A set of 2500 genomic loci was used to characterize the population. We assigned paternity to 769 (91%) progeny and the average number of fathers per mother plant was 37, from an average of 56 progeny examined per mother. An extensive number (80%) of pollination events occurred within 10 m of the mother plants. Pollination success was not correlated with trait attributes of the paternal genotypes. Mating system analysis confirmed that IWG is highly out-crossing and inbreeding was virtually absent. Neither genetic diversity nor the genome-estimated trait values of progeny were significantly affected by pollinator distance. The distance of pollinator in an IWG breeding nursery therefore was not found to be a major contributor in maintaining genetic diversity. These findings reveal the pollen dispersal model in IWG for the first time and its effect on genetic diversity, which will be valuable in designing future IWG breeding populations. Information generated and discussed in this study could be applied in understanding gene flow and genetic diversity of other open-pollinated species.</p>
Impacts of flowering density on pollen dispersal and gametic diversity are scale dependent
<p>Pollen dispersal is a key evolutionary and ecological process, but the degree to which variation in the density of concurrently flowering conspecific plants (i.e., co-flowering density) shapes pollination patterns remains understudied. We monitored co-flowering density and corresponding pollination patterns of the insect-pollinated palm <em>Oenocarpus bataua</em> in northwestern Ecuador and found that the influence of co-flowering density on these patterns was scale-dependent: high neighborhood densities were associated with reductions in pollen dispersal distance and gametic diversity of progeny arrays, whereas we observed the opposite pattern at the landscape scale. In addition, neighborhood co-flowering density also impacted forward pollen dispersal kernel parameters, suggesting that low neighborhood densities encourage pollen movement and may promote gene flow and genetic diversity. Our work reveals how co-flowering density at different spatial scales influences pollen movement, which in turn informs our broader understanding of the mechanisms underlying patterns of genetic diversity and gene flow within populations of plants.</p>
Patterns of pollen dispersal and pollen capture in the hybridizing cattails, Typha latifolia and T. angustifolia
<p><span>Pollen dispersal regulates the formation of the invasive, wind-pollinated hybrid cattail T. × glauca, the F1 offspring of the broadleaf (T. latifolia) and narrowleaf (T. angustifolia cattail. An earlier study suggested that pollen dispersal by T. latifolia might be spatially restricted, with most dispersal occurring over distances less than 2 m. Restricted pollen dispersal would imply that hybrid formation primarily occurs within mixed stands of cattails. Hybrid formation might also be affected by preferential receipt of conspecific pollen, but this has not been investigated for cattails. We compared patterns of pollen dispersal for T. latifolia and T. angustifolia using a wind tunnel. We then tested whether patterns of pollen receipt were biased toward the capture of conspecific versus heterospecific pollen using monospecific cattail stands with a single local pollen source. Results from the wind tunnel partially supported the previous finding of spatially restricted pollen dispersal for T. latifolia, the paternal parent of F1 hybrids. Pollen receipt by T. angustifolia was biased toward the capture of conspecific pollen. Localized pollen dispersal by T. latifolia and preferential conspecific pollen capture by T. angustifolia should reduce rates of hybrid formation below that expected under random mating.</span></p>
Mechanisms of male-male interference during dispersal of orchid pollen
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Patterns of pollen dispersal and pollen capture in the hybridizing cattails, Typha latifolia and T. angustifolia
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Influence of pollen dispersal and mating pattern in domestication of intermediate Wheatgrass, a novel perennial food crop
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Data from: Pre-dispersal seed predation and pollen limitation constrain population growth across the geographic distribution of Astragalus utahensis
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Impacts of flowering density on pollen dispersal and gametic diversity are scale dependent
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Patterns of pollen dispersal and mating in a population of the clonal plant Sagittaria latifolia
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Data from: Asymmetric contributions of seed and pollen to gene dispersal in the marsh orchid Dactylorhiza umbrosa in Asia Minor
<p>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 <i>Dactylorhiza umbrosa</i>, 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 (<i>mp/ms</i>) 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 of efficient seed dispersal.</p>
Data from: Effects of tree architecture on pollen dispersal and mating patterns in Abies pinsapo Boiss. (Pinaceae)
Plant architecture is crucial to pollination and mating in wind pollinated species. We investigate the effect of crown architecture on pollen dispersal, mating system and offspring quality, combining phenotypic and genotypic analyses in a low-density population of the endangered species Abies pinsapo. A total of 598 embryos from three relative crown height levels (bottom, middle, top) in five mother plants were genotyped using eleven nuclear microsatellite markers (nSSRs). Paternity analysis and mating system models were used to infer mating and pollen dispersal parameters. In addition, seeds were weighed (N = 16,110) and germinated (N = 736), and seedling vigour was measured to assess inbreeding depression. Overall, A. pinsapo shows a fat-tailed dispersal kernel, with an average pollen dispersal distance of 113–227 m, an immigration rate of 0.84–26.92%, and a number of effective pollen donors ranging between 3.5 and 11.9. We found an effect of tree height and relative crown height levels on mating parameters. A higher proportion of seeds with embryo (about 50%) and a higher rate of self-fertilization (about 60%) were found at the bottom level in comparison to the top level. Seed weight and seedling vigour are positively related. Nevertheless, no differences were found in seed weight or in seedling-related variables such as weight and length of aerial and subterranean parts among the different relative crown height levels, suggesting that seeds from the more strongly inbred bottom level are not affected by inbreeding depression. The different relative crown height levels also present a similar effective pollen dispersal distance and number of effective pollen donors, indicating vertical isotropy for outcross pollen. Our results thus suggest that self-pollen may compensate for the shortage of outcross pollen in low density populations.
Data from: Relative importance of pollen and seed dispersal across a Neotropical mountain landscape for an epiphtytic orchid.
Populations of many species are isolated within narrow elevation bands of Neotropical mountain habitat, and how well dispersal maintains genetic connectivity is unknown. We asked whether genetic structure of an epiphytic orchid, Epidendrum firmum, corresponds to gaps between Costa Rican mountain ranges, and how these gaps influence pollen and seed flow. We predicted that significant genetic structure exists among mountain ranges due to different colonization histories and limited gene flow. Furthermore, we predicted that pollen movement contributes more to gene flow than seeds because seeds are released into strong winds perpendicular to the narrow northwest-southeast species distribution, while the likely pollinators are strong fliers. Individuals from 12 populations and three mountain ranges were genotyped with nuclear microsatellites (nDNA) and chloroplast sequences (cpDNA). Genetic diversity was high for both markers, while nDNA genetic structure was low (FSTn = 0.020) and cpDNA structure was moderate (FSTc = 0.443). Significant cpDNA barriers occurred within and among mountain ranges, but nDNA barriers were not significant after accounting for geographic distance. Consistent with these contrasting patterns of genetic structure, pollen contributes substantially more to gene flow among populations than seed (mp/ms = 46). Pollinators mediated extensive gene flow, eroding nDNA colonization footprints, while seed flow was comparatively limited, possibly due to directional prevailing winds across linearly distributed populations. Dispersal traits alone may not accurately inform predictions about gene flow or genetic structure, supporting the need for research into the potentially crucial role of pollinators and landscape context in gene flow among isolated populations.
Data from: Unusually limited pollen dispersal and connectivity of Pedunculate oak (Quercus robur) refugial populations at the species' southern range margin
Low-latitudinal range margins of temperate and boreal plant species typically consist of scattered populations that persist locally in microrefugia. It remains poorly understood how their refugial habitats affect patterns of gene flow and connectivity, key components for their long-term viability and evolution. We examine landscape-scale patterns of historical and contemporary gene flow in refugial populations of the widespread European forest tree Pedunculate oak (Quercus robur) at the species' southwestern range margin. We sampled all adult trees (n = 135) growing in a 20 km long valley and genotyped 724 acorns from 72 mother trees at 17 microsatellite loci. The ten oak stands that we identified were highly differentiated and formed four distinct genetic clusters, despite sporadic historical dispersal being detectable. By far most contemporary pollination occurred within stands, either between local mates (85.6%) or through selfing (6.8%). Pollen exchange between stands (2.6%) was remarkably rare given their relative proximity and was complemented by long-distance pollen immigration (4.4%) and hybridization with the locally abundant Quercus pyrenaica (0.6%). The frequency of between-stand mating events decreased with increasing size and spatial isolation of stands. Overall, our results reveal outstandingly little long-distance gene flow for a wind-pollinated tree species. We argue that the distinct landscape characteristics of oaks' refugial habitats, with a combination of a rugged topography, dense vegetation and humid microclimate, are likely to increase plant survival but to hamper effective long-distance pollen dispersal. Moreover, local mating might be favoured by high tree compatibility resulting from genetic purging in these long-term relict populations.
Data from: Paternity analysis reveals wide pollen dispersal and high multiple paternity in a small isolated population of the bird-pollinated Eucalyptus caesia (Myrtaceae)
Optimal foraging behaviour by nectavores is expected to result in a leptokurtic pollen dispersal distribution and predominantly near-neighbour mating. However, complex social interactions among nectarivorous birds may result in different mating patterns to those typically observed in insect-pollinated plants. Mating system, realised pollen dispersal and spatial genetic structure were examined in the bird-pollinated Eucalyptus caesia, a species characterised by small, geographically disjunct populations. Nine microsatellite markers were used to genotype an entire adult stand and 181 seeds from 28 capsules collected from 6 trees. Mating system analysis using MLTR revealed moderate to high outcrossing (tm=0.479–0.806) and low estimates of correlated paternity (rp=0.136±s.e. 0.048). Paternity analysis revealed high outcrossing rates (mean=0.72) and high multiple paternity, with 64 different sires identified for 181 seeds. There was a significant negative relationship between the frequency of outcross mating and distance between mating pairs. Realised mating events were more frequent than expected with random mating for plants <40 m apart. The overall distribution of pollen dispersal distances was platykurtic. Despite extensive pollen dispersal within the stand, three genetic clusters were detected by STRUCTURE analysis. These genetic clusters were strongly differentiated yet geographically interspersed, hypothesised to be a consequence of rare recruitment events coupled with extreme longevity. We suggest that extensive polyandry and pollen dispersal is a consequence of pollination by highly mobile honeyeaters and may buffer E. caesia against the loss of genetic diversity predicted for small and genetically isolated populations.
Data from: Does long distance pollen dispersal preclude inbreeding in tropical trees? Fragmentation genetics of Dysoxylum malabaricum in an agro-forest landscape
Tropical trees often display long distance pollen dispersal, even in highly fragmented landscapes. Understanding how patterns of spatial isolation influence gene flow and interact with background patterns of fine scale spatial genetic structure are critical for evaluating the genetic consequences of habitat fragmentation. In the endangered tropical timber tree Dysoxylum malabaricum (Meliaceae) we apply eleven microsatellite markers with paternity and parentage analysis to directly estimate contemporary gene flow across a large area (216 km2) in a highly fragmented agro-forest landscape. A comparison of genetic diversity and genetic structure in adult and juvenile life stages indicates an increase of differentiation and fine-scale spatial genetic structure (FSGS) over time. Paternity analysis and parentage analysis demonstrate high genetic connectivity across the landscape by pollen dispersal. A comparison between mother trees in forest patches with low and high densities of adult trees shows that the frequency of short distance mating increases, as does average kinship among mates in low density stands. We interpret this as an early warning sign of potentially negative genetic consequences of forest fragmentation. Single isolated trees, in contrast, frequently receive heterogeneous pollen from distances exceeding five kilometres. We discuss the processes leading to the observed patterns of gene flow and the implications of this for conservation management of D. malabaricum and tropical trees more generally.
Data from: Evaluating the influence of different aspects of habitat fragmentation on mating patterns and pollen dispersal in the bird-pollinated Banksia sphaerocarpa var. caesia
Habitat fragmentation can significantly affect mating and pollen dispersal patterns in plant populations, although the differential effects of the various aspects of fragmentation are poorly understood. In this study we used paternity assignment with eight microsatellite loci to investigate the effect of fragmentation on the mating system and pollen dispersal within one large and eight small population remnants of Banksia sphaerocarpa var. caesia, a bird-pollinated shrub in the southern agricultural region of Western Australia. The large population had a much larger neighbourhood size and lower selfing rate, maternal pollen pool differentiation and within-plot mean pollen dispersal distance than the small populations. Outcrossing was consistently high and ranged from 89% ± 0.8 to 98.5% ± 0.3, and mating patterns suggested nearest-neighbour pollination. Pollen immigration into small populations ranged from 6% ± 0.6 to 15% ± 0.6. Using the small populations, we tested for correlations between various fragmentation variables and mating system and pollen dispersal parameters. We found significant positive linear relationships between population size and number of different fathers per seed crop and between population shape and pollen pool differentiation. There were significant negative linear relationships between population isolation and outcrossing rate; population shape and neighbourhood size; and conspecific density and mean pollen dispersal distance. Our results suggest that birds may use a series of fragmented populations as a vegetation corridor while foraging across the landscape and that population connectivity is a critical determinant of pollinator visitation. Our results also suggest that the effect of a linear population shape on the mating system and pollen dispersal is routinely underestimated.
Data from: Seed and pollen dispersal distances in two African legume timber trees and their reproductive potential under selective logging
The natural regeneration of tree species depends on seed and pollen dispersal. To assess if limited dispersal could be critical for the sustainability of selective logging practices, we performed parentage analyses in two Central African legume canopy species displaying contrasted floral and fruit traits: Distemonanthus benthamianus and Erythrophleum suaveolens. We also developed new tools linking forward dispersal kernels with backward migration rates to better characterize long-distance dispersal. Much longer pollen dispersal in D. benthamianus (mean distance dp=700m, mp=52% immigration rate in 6 km2 plot, s=7% selfing rate) than in E. suaveolens (dp=294m, mp=22% in 2 km2 plot, s=20%) might reflect different insect pollinators. At a local scale, secondary seed dispersal by vertebrates led to larger seed dispersal distances in the barochorous E. suaveolens (ds=175m) than in the wind-dispersed D. benthamianus (ds=71m). Yet, seed dispersal appeared much more fat-tailed in the latter species (15-25% seeds dispersing >500m), putatively due to storm winds (papery pods). The reproductive success was correlated to trunk diameter in E. suaveolens and crown dominance in D. benthamianus. Contrary to D. benthamianus, E. suaveolens underwent significant assortative mating, increasing further the already high inbreeding of its juveniles due to selfing, which seems offset by strong inbreeding depression. To achieve sustainable exploitation, seed and pollen dispersal distances did not appear limiting, but the natural regeneration of E. suaveolens might become insufficient if all trees above the minimum legal cutting diameter were exploited. This highlights the importance of assessing the diameter structure of reproductive trees for logged species.
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