Eichhornia Paniculata Research Articles

Assessment of autochthonous aquatic macrophytes with phytoremediation potential for dairy wastewater treatment in floating constructed wetlands

The phytoremediation potential of autochthonous aquatic plants has been increasingly explored. This study investigated the use of macrophytes found in natural ecosystems in the southern coast of the state of Bahia, Brazil, for treatment of dairy wastewater (DWW) using experimental systems of the floating constructed wetland type. Four species of aquatic macrophytes have been tested using floating platforms made from PET bottles. The chemical oxygen demand (COD), biochemical oxygen demand (BOD), total solids (TS), pH, and temperature of DWW were analyzed for 15 days. On the fifth day, a 74.8% (±7.7) decrease of BOD was achieved. Eichhornia crassipes (86.4%) and Eichhornia paniculata (84.8%) showed the best results, while Polygonum ferrugineum and Borreria scabiosoides achieved the removal of 65% and 74.2% of BOD, respectively. Considering the TS reduction in the DWW diluted with rainwater, the best results were obtained by Eichhornia crassipes (64.3%) and Eichhornia paniculata (65.18%). The macrophytes of the Eichhornia genus showed a greater potential for the treatment of DWW than the macrophytes Polygonum ferrugineum and Borreria scabiosoides, with a hydraulic retention time varying between four and five days.

The genetic architecture of tristyly and its breakdown to self-fertilization.

The floral polymorphism tristyly involves three style morphs with a reciprocal arrangement of stigma and anther heights governed by two diallelic loci (S and M). Tristyly functions to promote cross-pollination, but modifications to stamen position commonly cause transitions to selfing. Here, we integrate whole-genome sequencing and genetic mapping to investigate the genetic architecture of the M locus and the genetic basis of independent transitions to selfing in tristylous Eichhornia paniculata. We crossed independently derived semi-homostylous selfing variants of the long- and mid-styled morph fixed for alternate alleles at the M locus (ssmm and ssMM, respectively), and backcrossed the F1 to the parental ssmm genotype. We phenotyped and genotyped 462 backcross progeny using 1450 genotyping-by-sequencing (GBS) markers and performed composite interval mapping to identify quantitative trait loci (QTL) governing style-length and anther-height variation. A QTL associated with the primary style-morph differences (style length and anther height) mapped to linkage group 5 and spanned ~13-27.5Mbp of assembled sequence. Bulk segregant analysis identified 334 genes containing SNPs potentially linked to the M locus. The stamen modifications characterizing each selfing variant were governed by loci on different linkage groups. Our results provide an important step towards identifying the M locus and demonstrate that transitions to selfing have originated by independent sets of mating-system modifier genes unlinked to the M locus, a pattern inconsistent with a recombinational origin of selfing variants at a putative supergene.

Recent mating-system evolution in Eichhornia is accompanied by cis-regulatory divergence.

The evolution of predominant self-fertilization from cross-fertilization in plants is accompanied by diverse changes to morphology, ecology and genetics, some of which likely result from regulatory changes in gene expression. We examined changes in gene expression during early stages in the transition to selfing in populations of animal-pollinated Eichhornia paniculata with contrasting mating patterns. We crossed plants from outcrossing and selfing populations and tested for the presence of allele-specific expression (ASE) in floral buds and leaf tissue of F1 offspring, indicative of cis-regulatory changes. We identified 1365 genes exhibiting ASE in floral buds and leaf tissue. These genes preferentially expressed alleles from outcrossing parents. Moreover, we found evidence that genes exhibiting ASE had a greater nonsynonymous diversity compared to synonymous diversity in the selfing parents. Our results suggest that the transition from outcrossing to high rates of self-fertilization may have the potential to shape the cis-regulatory genomic landscape of angiosperm species, but that the changes in ASE may be moderate, particularly during the early stages of this transition.

The evolution of selfing is accompanied by reduced efficacy of selection and purging of deleterious mutations.

The transition from outcrossing to selfing is predicted to reduce the genome-wide efficacy of selection because of the lower effective population size (Ne) that accompanies this change in mating system. However, strongly recessive deleterious mutations exposed in the homozygous backgrounds of selfers should be under strong purifying selection. Here, we examine estimates of the distribution of fitness effects (DFE) and changes in the magnitude of effective selection coefficients (Nes) acting on mutations during the transition from outcrossing to selfing. Using forward simulations, we investigated the ability of a DFE inference approach to detect the joint influence of mating system and the dominance of deleterious mutations on selection efficacy. We investigated predictions from our simulations in the annual plant Eichhornia paniculata, in which selfing has evolved from outcrossing on multiple occasions. We used range-wide sampling to generate population genomic datasets and identified nonsynonymous and synonymous polymorphisms segregating in outcrossing and selfing populations. We found that the transition to selfing was accompanied by a change in the DFE, with a larger fraction of effectively neutral sites (Nes < 1), a result consistent with the effects of reduced Ne in selfers. Moreover, an increased proportion of sites in selfers were under strong purifying selection (Nes > 100), and simulations suggest that this is due to the exposure of recessive deleterious mutations. We conclude that the transition to selfing has been accompanied by the genome-wide influences of reduced Ne and strong purifying selection against deleterious recessive mutations, an example of purging at the molecular level.

Structural variations among monocot emergent and amphibious species from lakes of the semi-arid region of Bahia, Brazil

Temporary lakes are common in the semi-arid region of the State of Bahia and form water mirrors in the rainy season. In this period, various vegetal species appear having different life forms adapted to the seasonality conditions of the rainfall regime. This work surveyed the adaptive anatomical structures of some emergent and amphibious monocot species occurring in these lakes. We studied the anatomy of roots, rhizomes, leaves and scapes of Cyperus odoratus, Oxycaryum cubense, Pycreus macrostachyos (Cyperaceae) - amphibious species; and of Echinodorus grandiflorus (Alismataceae), Eichhornia paniculata (Pontederiaceae) and Habenaria repens (Orchidaceae) - emergent species. The anatomical features of the dermal, fundamental and vascular systems confirming the tendency of the adaptive convergence of these plants to temporary lacustrine the environment include: single layered epidermal cells with a thin cuticle layer in the aerial organs; the presence of air canals in all the organs; few or no supporting tissues; and less numerous conducting elements and thinner cell walls in the xylem. The reduction of the supporting tissues, the number of stomata, which can even be absent, and the number of conducting elements and the degree of cell wall lignification in the xylem of the emergent species is more accentuated than that of the amphibious species. The pattern of distribution of aerenchyma in the roots of the studied species was considered important to distinguish between amphibious and emergent life forms.

Mating-System Variation, Demographic History and Patterns of Nucleotide Diversity in the Tristylous Plant Eichhornia paniculata

Inbreeding in highly selfing populations reduces effective size and, combined with demographic conditions associated with selfing, this can erode genetic diversity and increase population differentiation. Here we investigate the role that variation in mating patterns and demographic history play in shaping the distribution of nucleotide variation within and among populations of the annual neotropical colonizing plant Eichhornia paniculata, a species with wide variation in selfing rates. We sequenced 10 EST-derived nuclear loci in 225 individuals from 25 populations sampled from much of the geographic range and used coalescent simulations to investigate demographic history. Highly selfing populations exhibited moderate reductions in diversity but there was no significant difference in variation between outcrossing and mixed mating populations. Population size interacted strongly with mating system and explained more of the variation in diversity within populations. Bayesian structure analysis revealed strong regional clustering and selfing populations were highly differentiated on the basis of an analysis of F(st). There was no evidence for a significant loss of within-locus linkage disequilibrium within populations, but regional samples revealed greater breakdown in Brazil than in selfing populations from the Caribbean. Coalescent simulations indicate a moderate bottleneck associated with colonization of the Caribbean from Brazil approximately 125,000 years before the present. Our results suggest that the recent multiple origins of selfing in E. paniculata from diverse outcrossing populations result in higher diversity than expected under long-term equilibrium.

Evolutionary pathways to self‐fertilization in a tristylous plant species

Evolutionary transitions from outcrossing to selfing occur commonly in heterostylous genera. The morphological polymorphisms that characterize heterostyly provide opportunities for different pathways for selfing to evolve. Here, we investigate the origins and pathways by which selfing has evolved in tristylous Eichhornia paniculata by providing new evidence based on morphology, DNA sequences and genetic analysis. The primary pathway from outcrossing to selfing involves the stochastic loss of the short-styled morph (S-morph) from trimorphic populations, followed by the spread of selfing variants of the mid-styled morph (M-morph). However, the discovery of selfing variants of the long-styled morph (L-morph) in Central America indicates a secondary pathway and distinct origin for selfing. Comparisons of multi-locus nucleotide sequences from 27 populations sampled from throughout the geographical range suggest multiple transitions to selfing. Genetic analysis of selfing variants of the L- and M-morphs demonstrates recessive control of the loss of herkogamy, although the number of factors appears to differ between the forms. Early stages in the establishment of selfing involve developmental instability in the formation of flowers capable of autonomous self-pollination. The relatively simple genetic control of herkogamy reduction and frequent colonizing episodes may often create demographic conditions favouring transitions to selfing in E. paniculata.

Directed seed dispersal and metapopulation response to habitat loss and disturbance: application toEichhornia paniculata

Summary 1 Seed dispersal is often directed towards locations with particular characteristics, particularly where seeds are dispersed by animals. The potential importance of directed seed dispersal for the response of plant metapopulations to habitat loss and changes in disturbance rate is assessed, and illustrated with a case study of a metapopulation of an aquatic plant. 2 The Levins model is extended to include preferential dispersal towards suitable habitat and towards unoccupied patches. Both increase patch occupancy, decrease the minimum habitat cover required for persistence and increase the maximum allowable disturbance rate, while preferential dispersal towards unoccupied patches also makes reductions in abundance due to increased disturbance rates more threshold-like. 3 Applying classical metapopulation approaches, which assume random dispersal, to a species that features directed dispersal, is expected to give systematic errors in prediction. For example, where dispersal is directed towards suitable habitat regardless of occupancy, the Levins model will tend to overestimate the response to habitat loss, and where dispersal is directed towards unoccupied patches, the Levins model will tend to underestimate the response to changes in disturbance rate. 4 Eichhornia paniculata is an aquatic plant restricted to ephemeral pools. Seed dispersal is by waterfowl, and so is directed towards suitable habitat. Data on habitat cover and patch occupancy from Husband and Barrett in 1998 fit well with our model but deviate significantly from the predictions of the Levins model. The parameter estimates imply dispersal very strongly directed towards suitable habitat, and that without this the minimum density of pools required for persistence would be at least 10 times greater than the highest densities observed, implying that the species would go locally extinct. 5 To our knowledge, this is the first quantitative demonstration that the nature and strength of directed dispersal affects the robustness of fragmented plant populations to anthropogenic disturbance. This calls for increased attention to be paid to the behaviour of seed-dispersing animals, and how this behaviour varies between different plant communities.

Equatorial Aperture Pattern in Monocots: Same Definition Rules as in Eudicots? The Example of Two Species of Pontederiaceae

Pontederia cordata L. and Eichhornia paniculata (Spreng.) Solms (Pontederiaceae, monocots) produce disulculate pollen grains. The formation of intersporal callose walls was followed in these two species by staining callose during male meiosis. A new type of cytokinesis that ends with the formation of conspicuous callose knobs at future aperture sites was observed. This observation indicates that the formation of the disulculate pattern is linked to cytokinesis. Thus, equatorial aperture patterns of monocots and aperture patterns of eudicots appear to be defined by similar mechanisms.

Evolution of floral display in Eichhornia paniculata (Pontederiaceae): genetic correlations between flower size and number

Abstract The evolution of floral display is thought to be constrained by trade-offs between the size and number of flowers and inflorescences. We grew in the glasshouse 60 maternal families from each of two Brazilian populations of the annual herb, Eichhornia paniculata. We measured flower size, daily flower number, and total flower number per inflorescence, and two indices of module size, leaf area and age at flowering. We also assessed the size and number of inflorescences produced over 6 weeks. All floral traits exhibited significant heritable variation, some of which was due to genetic variation in module size. Genetic (maternal family) correlations between daily and total flower number did not differ from 1.0, indicating that display size (daily flower number) cannot evolve independently from total flower number per inflorescence. Genetic correlations between flower size and daily flower number ranged from negative to positive (r=–0.78 to +0.84), depending on population and inflorescence. Positive correlations occurred when variation in investment per inflorescence was high so that some families produced both larger and more flowers. These correlations became zero when we controlled for variation in module size. Families that flowered later produced fewer, larger inflorescences (r=–0.33, –0.85). These data support theoretical predictions regarding the combined effects of variation in resource acquisition and allocation on traits involved in trade-offs, and they emphasize the hierarchical organization of floral displays. Our results imply that patterns of resource allocation among inflorescences influence evolutionary changes in flower size and number per inflorescence.

Effects of Population Size and Metapopulation Dynamics on a Mating-System Polymorphism

The evolutionary dynamics of neutral alleles under the Wright–Fisher model are well understood. Similarly, the effect of population turnover on neutral genetic diversity in a metapopulation has attracted recent attention in theoretical studies. Here we present the results of computer simulations of a simple model that considers the effects of finite population size and metapopulation dynamics on a mating-system polymorphism involving selfing and outcrossing morphs. The details of the model are based on empirical data from dimorphic populations of the annual plant Eichhornia paniculata, but the results are also of relevance to species with density-dependent selfing rates in general. In our model, the prior selfing rate is determined by two alleles segregating at a single diploid locus. After prior selfing occurs, some remaining ovules are selfed through competing self-fertilisation in finite populations as a result of random mating among gametes. Fitness differences between the mating-system morphs were determined by inbreeding depression and pollen discounting in a context-dependent manner. Simulation results showed evidence of frequency dependence in the action of pollen discounting and inbreeding depression in finite populations. In particular, as a result of selfing in outcrossers through random mating among gametes, selfers experienced a “fixation bias” through drift, even when the mating-system locus was selectively neutral. In a metapopulation, high colony turnover generally favoured the fixation of the outcrossing morph, because inbreeding depression reduced opportunities for colony establishment by selfers through seed dispersal. Our results thus demonstrate that population size and metapopulation processes can lead to evolutionary dynamics involving pollen and seed dispersal that are not predicted for large populations with stable demography.

Evolution of floral display in Eichhornia paniculata (Pontederiaceae): direct and correlated responses to selection on flower size and number.

Trade-offs between flower size and number seem likely to influence the evolution of floral display and are an important assumption of several theoretical models. We assessed floral trade-offs by imposing two generations of selection on flower size and number in a greenhouse population of bee-pollinated Eichhornia paniculata. We established a control line and two replicate selection lines of 100 plants each for large flowers (S+), small flowers (S-), and many flowers per inflorescence (N+). We compared realized heritabilities and genetic correlations with estimates based on restricted-maximum-likelihood (REML) analysis of pedigrees. Responses to selection confirmed REML heritability estimates (flower size, h2 = 0.48; daily flower number, h2 = 0.10; total flower number, h2 = 0.23). Differences in nectar, pollen, and ovule production between S+ and S- lines supported an overall divergence in investment per flower. Both realized and REML estimates of the genetic correlation between daily and total flower number were r = 1.0. However, correlated responses to selection were inconsistent in their support of a trade-off. In both S- lines, correlated increases in flower number indicated a genetic correlation of r = -0.6 between flower size and number. In contrast, correlated responses in N+ and S+ lines were not significant, although flower size decreased in one N+ line. In addition, REML estimates of genetic correlations between flower size and number were positive, and did not differ from zero when variation in leaf area and age at first flowering were taken into account. These results likely reflect the combined effects of variation in genes controlling the resources available for flowering and genes with opposing effects on flower size and number. Our results suggest that the short-term evolution of floral display is not necessarily constrained by trade-offs between flower size and number, as is often assumed.

Tres nuevos registros para México de plantas acuáticas vasculares

Se registran por primera vez para México, en particular del Istmo de Tehuantepec, Oaxaca, tres especies de plantas acuáticas vasculares, a mencionar: Bergia capensis L. (Elatinaceae), Eichhornia paniculata (Sprengel) Solms-Laub. (Pontederiaceae) y Nymphaea novogranatensis Wiersema (Nymphaeaceae).

EVOLUTION OF FLORAL DISPLAY IN EICHHORNIA PANICULATA (PONTEDERIACEAE): DIRECT AND CORRELATED RESPONSES TO SELECTION ON FLOWER SIZE AND NUMBER

Trade-offs between flower size and number seem likely to influence the evolution of floral display and are an important assumption of several theoretical models. We assessed floral trade-offs by imposing two generations of selection on flower size and number in a greenhouse population of bee-pollinated Eichhornia paniculata. We established a control line and two replicate selection lines of 100 plants each for large flowers (S ), small flowers (S−), and many flowers per inflorescence (N ). We compared realized heritabilities and genetic correlations with estimates based on restricted-maximum-likelihood (REML) analysis of pedigrees. Responses to selection confirmed REML heritability estimates (flower size, h2 = 0.48; daily flower number, h2 = 0.10; total flower number, h2 = 0.23). Differences in nectar, pollen, and ovule production between S and S− lines supported an overall divergence in investment per flower. Both realized and REML estimates of the genetic correlation between daily and total flower number were r = 1.0. However, correlated responses to selection were inconsistent in their support of a trade-off. In both S− lines, correlated increases in flower number indicated a genetic correlation of r = −0.6 between flower size and number. In contrast, correlated responses in N and S lines were not significant, although flower size decreased in one N line. In addition, REML estimates of genetic correlations between flower size and number were positive, and did not differ from zero when variation in leaf area and age at first flowering were taken into account. These results likely reflect the combined effects of variation in genes controlling the resources available for flowering and genes with opposing effects on flower size and number. Our results suggest that the short-term evolution of floral display is not necessarily constrained by trade-offs between flower size and number, as is often assumed.Corresponding Editor: J. Conner

Spatial and temporal variation in population size of Eichhornia paniculata in ephemeral habitats: implications for metapopulation dynamics

1 The annual plant Eichhornia paniculata occurs in discrete, ephemeral habitats formed by pools, wet ditches and flooded pastures in arid north‐eastern Brazil. We conducted a large‐scale geographical survey of populations four times over a 7‐year period (1982–89) and measured population size, population persistence and patch occupancy. In total, 167 populations were censused. 2 To investigate the importance of local and regional influences on population size, we posed the following specific questions. Are fluctuations in population size independent of their initial size and independent among years? Is persistence uniform among populations of different size and age? Are the proportion of patches occupied related to the density of habitat patches in a region? What are the relations between the size, persistence and density of populations? 3 Population size averaged 86 over the 4‐year period with 52% of populations containing less than 100 individuals. Sixty‐four per cent of populations persisted from one year to the next, but the rate at which populations became absent from a patch was independent of initial population size and time since the last census. For populations that persisted, there was a significant positive correlation between the initial census number and their size in subsequent years. 4 In 29 transects through different regions of north‐eastern Brazil, an average of 21.6% (range 3.8–47.2%) of suitable habitat patches were occupied by E. paniculata. The proportion of patches occupied was positively correlated with the density of patches in a region. No populations were found when the density of patches fell below 0.23 patches km−1 or 0.18 patches km−1 in 1988 and 1989, respectively, indicating the probable existence of a habitat threshold for species persistence within a region. There was no correlation between patch occupancy and either the average number of individuals per population or the probability of persistence in a region. Hence, even when E. paniculata is regionally common, it is not necessarily locally abundant. 5 We conclude that the distribution of E. paniculata populations in north‐eastern Brazil is governed, in part, by metapopulation dynamics.

Fertility differences among floral morphs following selfing in tristylous Eichhornia paniculata (Pontederiaceae): inbreeding depression or partial incompatibility?

Reduction in seed set following self‐ vs. cross‐pollination in flowering plants can result from abortion of selfed offspring owing to inbreeding depression and/or partial self‐incompatibility. Previous studies on tristylous Eichhornia paniculata (Pontederiaceae) indicate that reduced seed set following self‐pollination generally occurs in the short‐ (S), but not the long‐(L) or mid‐styled (M) morphs. To determine whether this pattern results from morph‐specific differences in inbreeding depression owing to the sheltering of deleterious alleles at the S locus and/or partial self‐incompatibility, we conducted controlled hand‐pollinations of the floral morphs and measured seed set and levels of seed abortion. There were no significant differences in fertilization success and seed set following self‐, illegitimate, and legitimate pollinations in the L and M morphs. In contrast, in the S morph self‐, intramorph and intermorph illegitimate pollinations resulted in significant reduction in seed set in comparison with legitimate pollination. This indicates that the reduced seed set observed in self‐pollination is the result of partial incompatibility rather than inbreeding depression. Significantly reduced fertilization success and low levels of ovule abortion in illegitimate pollinations of S plants also supported this conclusion. Reduced fertility in the S morph may have implications for the observed loss of this morph from natural populations and the evolutionary breakdown of tristyly.

Stamen elongation, pollen size, and siring ability in tristylous elchhornia paniculata (Pontederiaceae)

Selfing variants in tristylous Eichhornia paniculata (Pontederiaceae) possess an elongated, short‐level stamen adjacent to mid‐level stigmas, which causes autonomous selfing. The variants commonly spread in dimorphic, but not trimorphic populations in northeast Brazil. We investigated the effect of stamen elongation on pollen size and siring ability. Competition experiments using controlled hand‐pollination and allozyme markers were used to compare different pollen types. Pollen from the elongated stamen was significantly larger in size than pollen from unmodified short‐level stamens. In mixed pollinations of mid‐level stigmas, pollen from the elongated stamen sired significantly more seed than pollen from unmodified short‐level stamens. Despite these differences, the size and compatibility of pollen from the elongated stamen were more similar to short‐ than mid‐level pollen, indicating that alterations to stamen level were not associated with major changes in pollen characteristics. The results suggest that the advantage of selfing variants in dimorphic populations is mainly due to efficient pollen transfer to mid‐level stigmas rather than increased postpollination siring success of pollen from modified stamens. In addition, the absence of major changes in pollen size and compatibility associated with stamen elongation support other lines of evidence indicating that selfing variants are not the result of recombination in the putative heterostyly supergene.

Mating cost of large floral displays in hermaphrodite plants

HERMAPHRODITISM comprises outcrossing whenever the proximity of male and female organs allows self-fertilization1 and interference between sexual functions2. Many floral traits of animal-pollinated angiosperms encourage cross-fertilization3, as recognized by Darwin4-6; however, these characteristics may also allow pollination between flowers on the same individual (geitonogamous self-pollination) 7,8. Simultaneous display of many flowers exemplifies this conflict. Although large floral displays promote outcrossing through enhanced pollinator attraction9, they could be costly in terms of lost mating opportunities10,11 if geitonogamy decreased outcrossed siring success by reducing pollen transfer between plants (pollen discounting12). We report here that, after manipulating the flower number of bee-pollinated Eichhornia paniculata plants, we observed the predicted higher selfing and lower outcrossed siring success for larger inflorescences. Given the reduced fitness resulting when pollen receipt by one flower interferes with pollen export by another, we propose broadening traditional interpretations of floral design and display to recognize their roles in reducing geitonogamous pollen discounting.

POLLEN DISCOUNTING AND THE SPREAD OF A SELFING VARIANT IN TRISTYLOUS EICHHORNIA PANICULATA: EVIDENCE FROM EXPERIMENTAL POPULATIONS.

Floral traits that increase self-fertilization are expected to spread unless countered by the effects of inbreeding depression, pollen discounting (reduced outcross pollen success by individuals with increased rates of self-fertilization), or both. Few studies have attempted to measure pollen discounting because to do so requires estimating the male outcrossing success of plants that differ in selfing rate. In natural populations of tristylous Eichhornia paniculata, selfing variants of the mid-styled morph are usually absent from populations containing all three style morphs but often predominate in nontrimorphic populations. We used experimental garden populations of genetically marked plants to investigate whether the effects of population morph structure on relative gamete transmission by unmodified (M) and selfing variants (M') of the mid-styled morph could explain their observed distribution. Transmission through ovules and self and outcross pollen by plants of the M and M' morphs were compared under trimorphic, dimorphic (S morph absent), and monomorphic (L and S morphs absent) population structures. Neither population structure nor floral morphology affected female reproductive success, but both had strong effects on the relative transmission of male gametes. The frequency of self-fertilization in the M' morph was consistently higher than that of the M morph under all morph structures, and the frequency of self-fertilization by both morphs increased as morph diversity of experimental populations declined. In trimorphic populations, total transmission by the M and M' morphs did not differ. The small, nonsignificant increase in selfing by the M' relative to the M morph was balanced by decreased outcross siring success, particularly on the S morph. In populations lacking the S morph, male gamete transmission by the M' morph was approximately 1.5 times greater than that by the M morph because of both increased selfing and increased success through outcross pollen donation. Therefore, gamete transmission strongly favored the M' morph only in the absence of the S morph, a result consistent with the distribution of the M' morph in nature. This study indicates that floral traits that alter the selfing rate can have large and context-dependent influences on outcross pollen donation.

Pollen Discounting and the Spread of a Selfing Variant in Tristylous Eichhornia paniculata: Evidence from Experimental Populations

Pollen Discounting and the Spread of a Selfing Variant in Tristylous Eichhornia paniculata: Evidence from Experimental Populations