Pollen Dispersal Patterns Research Articles

Pollen dispersal patterns differ among sites for a wind-pollinated species and an insect-pollinated species.

Pollen dispersal, the main component of overall plant gene flow, generally decreases with increasing distance from the pollen source, but the pattern of this relationship may differ among sites. Although site-based differences in pollen dispersal may lead to over- or underestimation of gene flow, no studies have investigated pollen dispersal patterns among differing urban site types, despite the incongruent range of habitats in urban areas. We used paternity assignment to assess pollen dispersal patterns in a wind-pollinated species (waterhemp; Amaranthus tuberculatus) and in an insect-pollinated species (tomato; Solanum lycopersicum) in experimental arrays at four disparate sites (two roof-level sites, two ground-level sites) in the New York (New York, USA) metropolitan area. The number of seeds or fruits, a proxy for the number of flowers pollinated, decreased with increasing distance from the pollen donors at all sites for both species. However, the mean number of Amaranthus tuberculatusseeds produced at a given distance differed two-fold among sites, while the slope of the relationship between Solanum lycopersicumfruit production and distance differed by a factor of four among sites. Pollen dispersal patterns may differ substantially among sites, both in the amount of pollen dispersed at a given distance and in the proportional decrease in pollen dispersal with increasing distance, and these effects may act independently. Accordingly, the capacity of plant species to adapt to climate change and other selection pressures may be different from predictions based on pollen dispersal patterns at a single location.

Patterns of pollen dispersal and mating in a population of the clonal plant Sagittaria latifolia

Abstract 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. We investigated patterns of pollen dispersal, selfing and siring in a monoecious population of the clonal plant Sagittaria latifolia, 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. 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. 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.

Runaway fathers? Limited pollen dispersal and mating system in Rhizophora racemosa populations of a disturbed mangrove estuary

The contribution of pollen mediated gene flow in demographic stability is largely dependent on how far pollen can be dispersed, as well as how this dispersal affects the mating in breeding individuals. In this study patterns of pollen dispersal and mating systems in Rhizophora racemosa populations of the Cameroon Estuary complex (CEC) were assessed from 29 adult trees with their progeny seedlings (i.e., 483 propagules), sampled from three plots. Using progeny arrays constructed from eight microsatellite markers, we employed two-generational analyses to assess pollen pool structure, pollen dispersal distances, and mating systems. We found mean number of sires contributing to the pollen pool of a mother tree was low (2–3) and pollen dispersal distances were short (<12 m). Male gametic divergence among siblings was moderate (0.158 ≤ Φft ≤ 0.277). Low biparental inbreeding rates and moderate multi-locus outcrossing rates (0.559–0.650), suggest a mixed mating system comprising of spontaneous selfing (geitonogamy) and outcrossing. Our results show that pollen dispersal does not contribute to among patch genetic connectivity since the spatial scales of the patches far exceeds estimated pollen dispersal distances; indicating high gene flow previously reported within the CEC is predominantly mediated by propagule dispersal.

Combining rare alleles and grouped pollen donors to assign paternity in pollen dispersal studies

PremisePollen dispersal plays a critical role in gene flow of seed plants. Most often, pollen dispersal is measured using paternity assignment. However, this approach can be time‐consuming because it typically entails genotyping all pollen donors, receptors, and offspring at several molecular markers.MethodsWe developed a faster, simpler protocol to track paternity, using pollen receptors and grouped pollen donors that possess rare alleles. We tested this approach using wind‐pollinated Amaranthus tuberculatus and insect‐pollinated Solanum lycopersicum. After screening potential markers for rare alleles, we grew both species in experimental arrays under field conditions.ResultsAll tested A. tuberculatus seeds and 97% of S. lycopersicum fruits could be assigned to the grouped pollen donors using each of two markers. From these results, we could infer paternity of untested offspring and assess pollen dispersal patterns in each array.DiscussionBy combining rare alleles and grouped pollen donors, we could assess pollen dispersal for both species and across all arrays after genotyping a small number of pollen donors and a representative subset of offspring. While directly applicable to A. tuberculatus and S. lycopersicum, this approach could be used in other species to assess pollen dispersal under field conditions.

Pollen dispersal, pollen immigration, mating and genetic diversity in restoration of the southern plains Banksia

AbstractEvaluation of patterns of pollen dispersal, mating systems, population fitness, genetic diversity and differentiation in restoration and remnant plant populations can be useful in determining how well restoration activities have achieved their objectives. We used molecular tools to assess how well restoration objectives have been met for populations of Banksia media in the biodiversity hotspot of south-west Western Australia. We characterized patterns of pollen dispersal within, and pollen immigration into, two restoration populations. We compared mating system parameters, population fitness via seed weight, genetic diversity and genetic differentiation for restoration and associated reference remnant populations. Different patterns of pollen dispersal were revealed for two restoration sites that differed in floral display, spatial aggregation of founders and co-planted species. Proximity to remnant native vegetation was associated with enhanced immigration and more short-range pollen dispersal when other population variables were constant. Greater seed weights at remnant compared to restoration populations were not related to outcrossing rate. Equivalent mating system and genetic diversity parameters and low to moderate levels of genetic differentiation between restoration and remnant populations suggest pollinator services have been restored in genetically diverse restoration populations of local provenance B. media as early as four years from planting.

Patterns of Effective Pollen Dispersal in Larch: Linking Levels of Background Pollination with Pollen Dispersal Kernels

Monitoring patterns of mating and pollen dispersal in forest tree populations subjected to nature conservation is essential to understanding the dynamics of their reproductive processes and might be helpful in making management decisions aimed at conserving genetic diversity and integrity over the long term. However, little is known about effective pollen dispersal in natural populations of conifers, particularly in subdominant species such as larch. We investigated patterns of pollen dispersal in the Polish larch population of Świętokrzyski National Park. The studied population was located on Chełmowa Mountain in a forest complex 160 ha in size, which is relatively isolated from other forest stands. We assessed if local pollen dispersal inferred from pollen dispersal kernels could provide indications of the level of background pollination from sources located outside of the forest complex. The analysis focused on two plots, each encompassing 126 adult trees, and seed samples (n = 600) collected from 20 trees. Using 11 nuclear microsatellites and spatially explicit mating models, we identified details of mating patterns. The rate of self-fertilization was low (0.0268). Background pollination was moderate (0.4058), and the mean pollen dispersal was found to be 167 m and 111 m, based on exponential-power and Weibull dispersal kernels, respectively. Specific simulations performed based on the estimated pollen dispersal kernels provided background pollination levels comparable to those observed for real data, suggesting that the pollen contributing to background pollination likely originated from the studied forest complex and not from other surrounding populations. These results confirm the high potential for maintaining the genetic integrity of the larch population and support efforts aimed at promoting regeneration of the stands, either natural or through the artificial planting of seedlings derived from trees growing in the core larch population of the protected area.

Primary pollinator exclusion has divergent consequences for pollen dispersal and mating in different populations of a bird-pollinated tree.

Pollination by nectarivorous birds is predicted to result in different patterns of pollen dispersal and plant mating compared to pollination by insects. We tested the prediction that paternal genetic diversity, outcrossing rate and realized pollen dispersal will be reduced when the primary pollinator group is excluded from bird-pollinated plants. Pollinator exclusion experiments in conjunction with paternity analysis of progeny were applied to Eucalyptus caesia Benth. (Myrtaceae), a predominantly honeyeater-pollinated tree that is visited by native insects and the introduced Apis mellifera (Apidae). Microsatellite genotyping at 14 loci of all adult E.caesia at two populations (n=580 and 315), followed by paternity analysis of 705 progeny, revealed contrasting results between populations. Honeyeater exclusion did not significantly impact pollen dispersal or plant mating at Mount Caroline. In contrast, at the Chiddarcooping site, the exclusion of honeyeaters led to lower outcrossing rates, a threefold reduction in the average number of sires per fruit, a decrease in intermediate-distance mating and an increase in near-neighbour mating. The results from Chiddarcooping suggest that bird pollination may increase paternal genetic diversity, potentially leading to higher fitness of progeny and favouring the evolution of this strategy. However, further experimentation involving additional trees and study sites is required to test this hypothesis. Alternatively, insects may be effective pollinators in some populations of bird-adapted plants, but ineffective in others.

Stepping stones or stone dead? Fecundity, pollen dispersal and mating patterns of roadside Qualea grandiflora Mart. trees

Forest fragmentation may affect mating and pollen dispersal patterns through conversion of continuous forests into small, spatially isolated remnant patches and individual trees in an anthropogenic landscape. We investigated reproductive investment and success, pollen dispersal, mating system, and genetic diversity and spatial structure of Qualea grandiflora trees in two environmental contexts: a continuous natural Cerrado area and isolated individuals on roadsides. Roadside trees produced more flowers and more fruit than Cerrado trees. Pollen dispersal kernels were fat-tailed in both contexts, indicating long-distance dispersal, but in Cerrado the mean pollen dispersal distance (524.7 m) and the effective number of pollen donors per mother-tree (Nep = 12.7) were higher than for roadside trees (60.9 m, Nep = 4.6). The levels and structure of genetic diversity, outcrossing rates ( $$t_{m}$$ > 0.98), and mating among relatives ( $$t_{m} - t_{s}$$ < 0.1) were similar in both environmental contexts. Allelic richness and number of private alleles were similar between the two environments. The fixation index was significantly lower in adults (minimum of 0.08) than in offspring (minimum of 0.23) in both contexts, suggesting selection against inbred individuals between offspring and adult stage. Our results indicate that the spatial isolation of roadside trees, by increasing the number of flowers produced, decreased pollinator movements, thereby reducing effective pollen flow and the number of pollen donors. All these results suggest that roadside trees can be used for harvesting seeds for recovery plans, and that these trees are a biological legacy, and reservoir of Q. grandiflora genetic diversity, from the original Cerrado forest.

Mating system and pollen dispersal in Dipteryx alata Vogel (Leguminosae): comparing in situ and ex situ conditions

Dipteryx alata is a Neotropical tree widely distributed throughout the Brazilian Cerrado biome and is popularly known as baru. In this study, we evaluated the mating system of D. alata and compared pollen dispersal patterns between the in situ and ex situ conditions. For this, we used 515 genotypes of adults, juveniles, and progeny from a natural population (in situ) in Orizona-GO, Brazil. In addition, we used 488 genotypes of adults and progeny from a germplasm collection (ex situ) located at the Federal University of Goias. Both locations are situated in central Brazil. The genetic diversity, cross-pollination rates, and pollen dispersal distance under both conditions were estimated. Genetic diversity and polymorphism differed between the in situ and ex situ conditions. The average number of alleles found in situ (5.2) and ex situ (6.2) showed that the germplasm collection stores greater genetic diversity than the in situ condition. Cross-pollination detected among mother trees under both the in situ and ex situ conditions were high (tm = 0.815 and tm = 0.934, respectively), indicating that the species has a mixed reproductive system that was predominantly allogamous. The difference between tm and ts indicated that the in situ condition shows greater biparental inbreeding. Our results showed that, across generations, the ex situ condition preserved a larger number of alleles, confirming that the D. alata germplasm collection plays a role in conserving genetic diversity. The presence of self-fertilization suggests self-compatibility. Paternity correlation and the dispersal distance of the pollen donors were higher in the in situ condition, a maximum distance of 2.9 km of pollen flow. This can be explained by the number of pollinators and tree spatial distribution.

Effects of pollen contamination and non-random mating on inbreeding and outbreeding depression in a seedling seed orchard of Eucalyptus urophylla

Microsatellite loci were used to assess pollen contamination and mating patterns in an Eucalyptus urophylla seedling seed orchard (SO2) along with inbreeding and outbreeding depression in a second generation progeny test (PT2) established with SO2 seeds. We measured survival, diameter at breast height (DBH), and height (H) in SO2, PT2, and two other stands (SO1, PT) located at a distance of at least 210 m from SO2. Pollen contamination was substantial (11.9%), with the largest proportion coming from the closer SO1 stand (6.1%) than PT (4.7%) and 1.1% from unknown sources. The pollen dispersal pattern was isolation by distance but reached long distances (600 m). PT2 offspring were mainly the result of outcrossing (92.6%), but mating in SO2 was not random due to self-fertilization (7.4%), mating among relatives (6.6%), correlated mating (13.7%), and high male fertility success of trees with large DBH. Thus, families are a mixture of different levels of relatedness and some inbreeding (12.7%). Inbreeding depression was variable among traits; it was higher for selfing (39.6–49.5%) than mating among relatives (11.6–20.9%) and higher for mating between full-sibs (4.4%) than half-sibs (2.2%). Outbreeding depression was higher for pollen immigration from less improved sources (33.9–41.2%). Non-random mating resulted in a coancestry (0.152) higher than expected for half-sib families and an overestimation of heritability by 17.8%. Our results indicate that isolation distances greater than 600 m are necessary to avoid pollen contamination in Eucalyptus seed orchards. Furthermore, pollen immigration results in outbreeding depression, and selfing results in higher levels of inbreeding depression than mating among related trees.

A genetic approach to study mating system on Jabon Merah (Anthocephalus macrophyllus Roxb.) from three different provenances in South Sulawesi

Jabon merah (Anthocephalus macrophyllus) is fast-growing species that endemic to Indonesia, particularly Sulawesi and Maluku. Studies on pollen dispersal and pollination type assist to determine whether the species suffering inbreeding depression in the population. This study investigated the mating system and pollen dispersal pattern on A. macrophyllus in its habitat distribution based on microsatellite marker (SSR). Here, we collected leaf samples from three different locations in South Sulawesi, Luwu, Wajo, and Sidrap, and conducted molecular analysis at Biotechnology and Tree Breeding Laboratory, Faculty of Forestry, Hasanuddin University, Makassar. The analyses indicated A. macrophyllus tended to do outcrossing in each evaluated population. Means of outcrossing and selfing rates observed in the populations were 76,9% and 23,1%, respectively. Distance pollen travel could reach up to 339 m, and the frequencies of pollinations were varied from 1 to 7 times. The findings indicate individuals of Jabon merah in the populations may not be threatened by inbreeding depression due to outcrossed pollination nature.

Short-distance pollen dispersal by bats in an urban setting: monitoring the movement of a vertebrate pollinator through fluorescent dyes

Pollen dispersal in tropical seed plants is established mainly by biotic vectors, both in intact and fragmented environments. In urban landscapes, the segregation of natural remnants by an artificial matrix can reduce pollinator foraging efficiency. It is unknown how nectarivorous bats, regarded as long-distance pollen dispersers, respond to such habitat structure combined with city-related factors. Here, we investigated the pollen dispersal pattern between spatially segregated individuals of the bat-pollinated Bignoniaceae Crescentia cujete within an urban environment. From 2015 to 2017, we assessed their spatiotemporal structure, breeding system and annual fruit set in order to relate these factors to the bat activity in the region. We employed fluorescent dyes as pollen analogues to infer the role of bats in pollen flow. Adding to the low density of individuals, we found a low daily flower emission and low flowering synchrony (S = 0,092), all of which are traits that favor outcrossing. Individuals were distributed in two distant groups (>600 m), with no occurrence of dye flow between them. In contrast, flow within the same individual was intense, which points toward bats’ territorial behavior. C. cujete is self-compatible, but not autogamous; therefore, despite few outcross events, bats could be ensuring the plant’s year-round fruit production mainly through self-pollination. Our findings show restricted bat foraging extent, which affects overall pollen dispersal distance and population connectivity. These results can be extrapolated to natural metapopulations inserted in an urban matrix and serve as a groundwork for studying directly the effect of city-related factors on pollinator behavior.

Patterns of Pollen Dispersal in an Invasive Population of Solanum rostratum (Solanaceae) in China

Paternity analysis, carried out on 13 microsatellite loci, was used to investigate pollen dispersal and mating patterns in an invasive population of Solanum rostratum in China. We determined a high outcrossing rate (0.81 ± 0.02) and found that all 174 offspring for which the father could be identified were outcross progeny. The mean pollen dispersal distance was 13.66 m (range 0.41–71.67 m); however, 59.2% of effective pollination events occurred at <10 m. Our results indicate substantial near-neighbor pollen dispersal and imply that successful invasion of S. rostratum is facilitated by a high level of pollen flow within the population.

The Relationship of Pollen Dispersal with Allergy Symptoms and Immunotherapy: Allergen Immunotherapy Improves Symptoms in the Late Period of Japanese Cedar Pollen Dispersal

Background: The severity of symptoms of pollen-induced allergic rhinitis is affected by the amount of scattered pollen. However, the relationships between the pollen dispersal pattern, symptom severity, and treatment efficacy are not clear. Methods: Between 2007 and 2012, we performed 4 randomized, placebo-controlled studies of sublingual immunotherapy (SLIT) on patients with Japanese cedar-induced allergic rhinitis who lived in or around Chiba, Japan. The participants were asked to avoid using rescue medicines during the cedar pollen season as much as possible and to record their nasal symptoms in allergy diaries. The amount of pollen dispersed daily was quantified using the Durham method, and the season was divided into early and late periods based on the pollen count. Results: A total of 721 patients were enrolled in the 4 studies during the 6-year study period. In the placebo group (n = 349), a correlation was observed between the amount of pollen dispersed and the severity of symptoms in the early but not late period of pollen dispersal. Treatment with SLIT (n = 372) significantly improved symptom severity in the late but not early period. Conclusion: For patients with Japanese cedar pollen-induced allergic rhinitis, the fluctuation of daily pollen dispersal had a minimal effect on the severity of symptoms during the late period. SLIT was remarkably effective in alleviating symptoms during this period but not in the early period.

The relative contributions of seed and pollen dispersal to gene flow and genetic diversity in seedlings of a tropical palm.

Seed and pollen dispersal shape patterns of gene flow and genetic diversity in plants. Pollen is generally thought to travel longer distances than seeds, but seeds determine the ultimate location of gametes. Resolving how interactions between these two dispersal processes shape microevolutionary processes is a long-standing research priority. We unambiguously isolated the separate and combined contributions of these two dispersal processes in seedlings of the animal-dispersed palm Oenocarpus bataua to address two questions. First, what is the spatial extent of pollen versus seed movement in a system characterized by long-distance seed dispersal? Second, how does seed dispersal mediate seedling genetic diversity? Despite evidence of frequent long-distance seed dispersal, we found that pollen moves much further than seeds. Nonetheless, seed dispersal ultimately mediates genetic diversity and fine-scale spatial genetic structure. Compared to undispersed seedlings, seedlings dispersed by vertebrates were characterized by higher female gametic and diploid seedling diversity and weaker fine-scale spatial genetic structure for female gametes, male gametes and diploid seedlings. Interestingly, the diversity of maternal seed sources at seed deposition sites (Nem ) was associated with higher effective number of pollen sources (Nep ), higher effective number of parents (Ne ) and weaker spatial genetic structure, whereas seed dispersal distance had little impact on these or other parameters we measured. These findings highlight the importance maternal seed source diversity (Nem ) at frugivore seed deposition sites in driving emergent patterns of fine-scale genetic diversity and structure.

Mating patterns and pollen dispersal in a Japanese larch (Larix kaempferi) clonal seed orchard: a case study.

Pollination dynamics highly determines the genetic quality of seed orchard crops. However, there is less research about the effect of mating patterns on seed productivity of orchard crops. So far, clonal seed orchards have been producing genetically improved seedlings used for most Japanese larch (Larix kaempferi (Lamb.) Carr.) plantations in China. In the present study, a total of 17 highly variable simple sequence repeat (SSR) markers were used for genotyping a progeny trial population consisting of 647 open-pollinated progenies germinated from seeds which were collected from 63 maternal clones with 140 potential paternal clones in a Japanese larch clonal seed orchard in China. Paternity analysis was used in the present case study in order to evaluate the level of paternal gametic contribution, estimate pollen contamination and selfing rates, and investigate pollination patterns, pollen dispersal patterns and the impact of mating patterns on seed productivity of orchard crops. We observed 93.7% of the success rate of the parental assignment, unequal paternal gametic contribution (0-12.4%) with 6.3% of the progenies derived from pollen contamination or unsampled pollen donors, and absence of evidence for selfing. We also found that pollination rate highly depended on the distance between pollen donors and maternal parents, the majority of the identified crossing (65.7%) occurred between clones within a 150-m radius, and large variations in growth performance existed among the paternal half-siblings. Progeny growth performance (diameter at breast (DBH) and height (HGT)) was measured at Age-20 in order to investigate the impact of mating patterns on timber production of orchard crops. As either the paternal or maternal, two clones (i. e., clones Z38 and Z62) were identified to have produced progenies with higher average stem volume breeding values than that of all of the progenies. Specifically, the genetic gains for volume were 3.53% for the two clones as paternal parents, and 8.26% as the maternal parents at Age-20. Thus, both elite clones were ideal candidates for the construction of next-generation clonal seed orchards due to their synchronous reproductive phenology with greater crossing rate and higher genetic gain. These results improved the pedigree information to provide solid evidence of mating patterns for future design and effective management of seed orchards and for the development of viable long-term breeding strategies for other coniferous species.

Population density and size influence pollen dispersal pattern and mating system of the predominantly outcrossed Banksia nivea (Proteaceae) in a threatened ecological community

Gene flow is a critical component of plant mating systems and influences population fitness. However, pollen dispersal can be highly variable and influenced by natural and anthropogenic fragmentation. Gene flow through pollen dispersal was investigated in two populations of contrasting size and habitat context in Banksia nivea ssp. uliginosa, a rare species in the Busselton ironstone threatened ecological community of Western Australia with a naturally fragmented distribution. Paternity analysis was conducted with seven microsatellite loci to determine mating system parameters and patterns of pollen dispersal. Outcrossing was high in both populations with a similar level of selfing for both populations despite differences in population size, density and vegetation matrix. Most mating occurred within 10 m of a mother plant in the small, clumped population, while more dispersed mating, up to 50 m from a mother plant, was recorded in the large, less dense population. Our results show that population density and size are important influences on mating system parameters and level of pollen dispersal.

HIGH OUTCROSSING RATE AND POLLEN DISPERSAL DISTANCE of Diospyros celebica Bakh. (EBENACEAE), AN ENDEMIC TREE SPECIES IN SULAWESI ISLAND, INDONESIA

Diosphyros celebica Bakh., also known as Sulawesi ebony, is an endemic to central and northern Sulawesi. Information about pollen dispersal patterns of D. celebica have not been previously investigated. This study was aimed to determine pollination type, percentage of selfing and outcrossing, as well as distance of pollen dispersal of D. celebica. This study was conducted at experimental forest of Universitas Hasanuddin, Maros District, South Sulawesi Province, Indonesia. One hundred and sixty six individuals of D. celebica consisted of adult trees and seedlings were analyzed in this study. Ninety four adult trees were selected to become parent trees. The trees were mapped with GPS coordinates . All samples were genotyped using four SSR markers loci. Parental analysis and determination of pollen dispersal patterns were carried out using Cervus 3.0.3. Results indicated that the evaluated markers were effective for assigning candidate of male parents to all evaluated seedlings. Donated pollens could come from male parents in any directions relative to female parent positions. Pollen dispersal pattern showed outcrossing pollination among different male parents (pollen donated trees). The results indicated that seeds were produced predominatly by outcrossing. Pollen dispersal reached up to 166 m. Pollen related processes were linked through female parents, pollinators availability and ecological environment. Simultaneous use of progeny genotyping, spatially explicit analysis of environmental variables and outcomes of plant–animal interactions, were the key elements for an expanded approach to gene flow analysis considering dispersal via pollen and seeds. Research on pollen dispersal of D. celebica should be carried out in other forest types, such as mixed forest and highland forest.

Dipteryx alata Vogel (Fabaceae) a neotropical tree with high level of selfing: implication for conservation and breeding programs

Dipteryx alata (Fabaceae) is a threatened tropical tree of the Brazilian Savanna. Due to deforestation of its biome, many individuals and populations are now spatially isolated in forest fragments, pastures, and along roads. Plans for in situ and ex situ conservation of the species are urgently needed. To support conservation, the mating system and pollen dispersal patterns must be better understood as they determine the levels of genetic diversity, inbreeding, and effective size of seed generations. Microsatellite were used to investigated the mating system, pollen dispersal, genetic diversity, spatial genetic structure (SGS), and inbreeding in isolated trees in pastures and along roads from two populations with different densities in the Brazilian Savanna. Our aim is to determine the potential of these trees to contribute to seed collection for genetic conservation. We found that the species presents a mixed mating system, strong individual variation in outcrossing rate (0.01-1.0), and non-random mating. Low population density resulted in lower levels of outcrossing (tm = 0.45) and mating among relatives (tm - ts = 0.12), but longer pollen dispersal distances (δ = 6,572 m) than in the higher density populations (tm = 0.90, tm - ts = 0.26, δ = 1,395 m). Mating among relatives was explained by SGS detected in the populations, associated with near-neighbor pollinator foraging behavior. Correlated mating indicates that a low effective number of pollen donors (1.5-10.3) fertilized the trees. Thus, open-pollinated seedling families present mixtures of different levels of relatedness and inbreeding. Our results are discussed in light of strategies for in and ex situ conservation.

Carpinus betulus pollen accumulation rates in Roztocze (SE Poland) in relation to presence of Carpinus in Ferdynandovian pollen diagrams

Carpinus pollen has been recorded in fossil pollen diagrams of different interglacials. In case of the Ferdynandovian pollen sequence it is of particular importance to know if scattered presence of Carpinus pollen at the decline of Ferdynandovian 1 interglacial represents long distance transport of pollen or small isolated Carpinus populations. The study aims to trace the pollen-vegetation relationship in Roztocze (SE Poland) using Tauber-style pollen traps to understand better the pattern of Carpinus pollen dispersal and deposition. High and low pollen deposition years were recorded for Carpinus betulus in the period 1998–2010. Deposition was extremely high in 2002. Average annual pollen accumulation rate was calculated at 1348 grains cm -2 year -1 , which was 4.1% of total pollen spectrum. The study confirms that the earlier pollen presence/absence threshold values of about 5% for the presence of Carpinus trees in vegetation (Huntley & Birks 1983) were too high. The pollen monitoring data from Roztocze support the opinion of Ralska-Jasiewiczowa et al. (2004) that low values of about 0.5% may reflect the presence of Carpinus trees in the forests. These data, in comparison to the scattered Carpinus pollen grains in the last part of the Ferdynandovian 1 interglacial seem to indicate that single trees of this genus may nave occurred in the vegetation at the decline of interglacial optimum.