Definition of plant functional groups for informing implementation scenarios in resource-limited multi-species recovery planning

We describe an approach to multi-species recovery planning and bio-regional biodiversity assessment that uses trait-based plant functional groups as the basis for developing threat/risk assessments for rare, threatened and ‘of concern’ species. Multi-variate methods were used to extract and test emergent groups, and additional information fields related to species life history and distributional data were added to develop a species-level information assessment matrix in spreadsheet format. Relating emergent trait-based plant functional groups to habitat was found to be the most informative approach for the subsequent development of management recommendations and landscape scale threat/risk assessment to inform recovery planning. Examples on the use of the identified groups in a management context are provided. These include higher and lower resource and data availability scenarios, and the role of selected traits in adding to or ameliorating threats and risk of extinction.     

Towards integrated conservation of Australian endangered plants—the Western Australian model

Four percent of the Australian flora is rare and endangered with over 100 taxa presumed extinct. Western Australia contains a large proportion of the endangered flora of Australia with 238 taxa in a critical state of conservation and 70 species presumed extinct. Kings Park and Botanic Garden in south-west Australia is responsible for developing specialized collections of rare and endangered indigenous flora. Macro-and micropropagation procedures are used including conventional cutting and seed propagation, grafting and in thein vitro programme whole seeds (asymbiotic and symbiotic germination), excised seed embryos, shoot apices and inflorescence sections. Wherever possible explants are collected from major provenances of the species and a wide cross section of a species population. Although many of the rare flora of Western Australia are now in theex situ collection maintained by Kings Park and Botanic Garden attempts are being made to develop slow growth storage forin vitro cultures and cryostorage. Trial recovery programmes have commenced with a number of species including the rare and endangered Purdie's donkey orchid (Diuris purdiei). Results of these recovery programmes will guide future efforts in conserving and recovering rare Australian species.     

Functional groups of rare plants differ in levels of imperilment

Comparative examination of a large sample of plant species can reveal important aspects of life history that influence the ecology and distribution of taxa and their vulnerability to local extinction. We investigated whether functional groups of 71 rare plant species with contrasting life history traits differed in terms of population losses over time, regional range contraction, and range-wide levels of imperilment. Using town-level occurrence data from herbaria and Natural Heritage Program databases, we characterized species' extents of occurrence as α-hulls encompassing the centroids of New England towns that contained well-documented populations of these rare taxa. Family affiliation was used as a covariate in analyses to reduce phylogenetic bias. Disparate functional groups of plants differed both in proportions of populations lost and declines in range areas over time, with insect-pollinated taxa, upland (vs. wetland) taxa, species with localized seed dispersal modes, and taxa reaching their northern range boundary in New England significantly more imperiled than other functional groups. These techniques permit a broad comparative assessment of the distribution of large numbers of plant taxa, so that we can identify several functional groups that warrant more concerted conservation attention.     

海拔对全缘叶绿绒蒿植株性状和花特征的表型选择分析

为了研究海拔差异对植株性状、花特征表型选择的影响,以青藏高原高寒草甸的全缘叶绿绒蒿（Meconopsis integrifolia）为研究材料,于盛花期内,测定不同海拔（4 452、4 081和3 681 m）种群中个体植株性状、花特征、单果结实数并进行统计分析,采用线性回归模型估计不同海拔种群间植株性状、花特征所受的表型选择（选择差与选择梯度）。结果表明：（1）随着海拔升高,全缘叶绿绒蒿植株性状、花特征及单果结实数显著降低,海拔越高的种群中株高越矮、叶面积越小、花数越少、花越小、单果结实数越低。（2）不同海拔种群中各性状的表型选择存在差异,较低海拔（3 681 m）种群中花数、花大小具有显著的选择差和选择梯度,表现为花越多、花越大的个体雌性适合度越高;海拔较高（4 081 m）的种群中株高、叶面积及花数更容易受到选择,表现为植株越高、叶面积越大、花越多的个体雌性适合度越高;海拔最高（4 452 m）的种群中叶面积与花数的选择梯度接近显著。（3）植物性状分化伴随着海拔的变化而呈现出差异,较低海拔种群中花特征容易受到选择,而较高海拔种群中可能由于传粉者稀少、资源限制等因素使得株高、叶面积更容易受到选择。     

Does the surrounding matrix influence corridor effectiveness for pollen dispersal in farmland?

Recent decades have seen a shift in agricultural land use from pasture to arable combined with increased use of fertilisers and pesticides. In this quite hostile landscape matrix, pollinator movements between native vegetation remnants may be impeded. Linear landscape elements (LLEs) in farmland can function as biological corridors by facilitating pollinator movements and pollen flow between fragmented plant populations. The type of landscape matrix surrounding LLEs and plant populations, and LLE habitat quality may influence the effectiveness of LLEs as corridors for pollen dispersal through the availability of floral resources and nesting opportunities for pollinators. Using fluorescent dyes as pollen analogues, we investigated dye dispersal patterns between fragmented populations of the rare insect-pollinated Primula vulgaris connected by existing LLEs. We examined how dye deposition on P. vulgaris and within LLEs (on other co-flowering insect-pollinated species) could be influenced by the surrounding matrix type (pasture, arable field), the recipient population traits of P. vulgaris (flowering population size, flower display, flowering plant density and co-flowering floral resources) and by LLE traits (LLE length and co-flowering floral resources). Dye dispersal through corridors was significantly higher when the landscape matrix surrounding P. vulgaris recipient populations and LLEs consisted of pastures rather than arable fields (or a mix of both), even after accounting for differences in floral resources. A higher cover and diversity of insect-pollinated plants increased dye deposition when co-flowering within small P. vulgaris populations, but led to dye loss within LLEs. Large P. vulgaris populations appeared more attractive thereby increasing heterospecific dye deposition in the LLEs. Our study shows that farming practices shifting from pastures to maize arable fields have a negative impact on dye dispersal patterns, and so possibly affect pollen dispersal of P. vulgaris, likely through a reduced pollinator service. Corridor effectiveness depends on the type of surrounding matrix, and the abundance of floral resources directly influences dye dispersal patterns. Preserving the remaining pastureland is essential, but restoring rich flowering vegetation at field boundaries and along LLEs may also promote corridor effectiveness for pollen dispersal.     

Pleiotropic quantitative trait loci contribute to population divergence in traits associated with life-history variation in Mimulus guttatus

Evolutionary biologists seek to understand the genetic basis for multivariate phenotypic divergence. We constructed an F2 mapping population (N = 539) between two distinct populations of Mimulus guttatus. We measured 20 floral, vegetative, and life-history characters on parents and F1 and F2 hybrids in a common garden experiment. We employed multitrait composite interval mapping to determine the number, effect, and degree of pleiotropy in quantitative trait loci (QTL) affecting divergence in floral, vegetative, and life-history characters. We detected 16 QTL affecting floral traits; 7 affecting vegetative traits; and 5 affecting selected floral, vegetative, and life-history traits. Floral and vegetative traits are clearly polygenic. We detected a few major QTL, with all remaining QTL of small effect. Most detected QTL are pleiotropic, implying that the evolutionary shift between these annual and perennial populations is constrained. We also compared the genetic architecture controlling floral trait divergence both within (our intraspecific study) and between species, on the basis of a previously published analysis of M. guttatus and M. nasutus. Eleven of our 16 floral QTL map to approximately the same location in the interspecific map based on shared, collinear markers, implying that there may be a shared genetic basis for floral divergence within and among species of Mimulus.     

Evolution of pollination niches and floral divergence in the generalist plant Erysimum mediohispanicum

Background and Aims

How generalist plants diverge in response to pollinator selection without becoming specialized is still unknown. This study explores this question, focusing on the evolution of the pollination system in the pollination generalist Erysimum mediohispanicum (Brassicaceae).

Methods

Pollinator assemblages were surveyed from 2001 to 2010 in 48 geo-referenced populations covering the entire geographic distribution of E. mediohispanicum. Bipartite modularity, a complex network tool, was used to find the pollination niche of each population. Evolution of the pollination niches and the correlated evolution of floral traits and pollination niches were explored using within-species comparative analyses.

Key Results

Despite being generalists, the E. mediohispanicum populations studied can be classified into five pollination niches. The boundaries between niches were not sharp, the niches differing among them in the relative frequencies of the floral visitor functional groups. The absence of spatial autocorrelation and phylogenetic signal indicates that the niches were distributed in a phylogeographic mosaic. The ancestral E. mediohispanicum populations presumably belonged to the niche defined by a high number of beetle and ant visits. A correlated evolution was found between pollination niches and some floral traits, suggesting the existence of generalist pollination ecotypes.

Conclusions

It is conjectured that the geographic variation in pollination niches has contributed to the observed floral divergence in E. mediohispanicum. The process mediating this floral divergence presumably has been adaptive wandering, but the adaptation to the local pollinator faunas has been not universal. The outcome is a landscape where a few populations locally adapted to their pollination environment (generalist pollination ecotypes) coexist with many populations where this local adaptation has failed and where the plant phenotype is not primarily shaped by pollinators.     

Influence of plant domestication on plant-pollinator interactions: Floral attributes and floral visitor communities in wild and cultivated squash plants

Premise

Domestication of plant species results in phenotypic modifications and changes in biotic interactions. Most studies have compared antagonistic plant-herbivore interactions of domesticated plants and their wild relatives, but little attention has been given to how domestication influences plant-pollinator interactions. Floral attributes and interactions of floral visitors were compared between sister taxa of the genus Cucurbita (Cucurbitaceae), the domesticated C. moschata, C. argyrosperma ssp. argyrosperma and its wild progenitor C. argyrosperma ssp. sororia in the place of origin.

Methods

We conducted univariate and multivariate analyses to compare floral morphological traits and analyzed floral reward (nectar and pollen) quantity and quality between flowers of wild and domesticated Cucurbita taxa. Staminate and pistillate flowers of all three taxa were video recorded, and visitation and behavior of floral visitors were registered and analyzed.

Results

Most floral morphological characteristics of flowers of domesticated taxa were larger in both staminate and pistillate flowers. Staminate and pistillate flowers presented distinct correlations between floral traits and integration indices between domesticated and wild species. Additionally, pollen quantity and protein to lipid ratio were greater in domesticated species. Cucurbit pollen specialists, Eucera spp., had the highest probability of visit for all Cucurbita taxa.

Conclusions

We provide evidence that floral traits of domesticated and wild Cucurbita species experienced different selection pressures. Domesticated Cucurbita species may have more resources invested towards floral traits, thereby increasing attractiveness to pollinators and potentially plant reproductive success. Wild ancestor plant populations should be conserved in their centers of origin to preserve plant-pollinator interactions.     

Adaptive inter-population differences in blue tit life-history traits on Corsica

Few studies of natural populations have investigated how phenotypic variation across populations relates to key factors in the environment and landscape structure. In the blue tits of southern France, inter-population differences in reproductive life-history traits (e.g. laying date and clutch size) are small, whatever the timing of maximum caterpillar availability, a key factor for offspring survival in tits. These small differences are attributed to gene flow between local populations occupying different habitat types. In contrast, in blue tits on the island of Corsica, we noted large differences in reproductive life-history traits between two populations, where each population is synchronized with the peak-date of caterpillar abundance. These occur over a short geographical distance (25km). Considering our study within a framework of long-term population studies in tits, our results support the hypothesis that different blue tit populations on Corsica show adaptive differences in life-history traits, and suggest that landscape structure at a small spatial scale can have profound effects on adaptive between-population differentiation in life-history traits that are closely linked with fitness.     

Relaxed pollinator-mediated selection weakens floral integration in self-compatible taxa of Leavenworthia (Brassicaceae)

Natural selection should favor the integration of floral traits that enhance pollen export and import in plant populations that rely upon pollinators. If this is true, then phenotypic correlations between floral traits should weaken in self-fertilizing groups that do not require pollinator visitation to produce seed. We tested this hypothesis in Leavenworthia, a plant genus in which there have been multiple independent losses of the sporophytic self-incompatibility system found throughout the Brassicaceae. In particular, we conducted phylogenetically independent contrasts of floral trait correlations between two pairs of self-incompatible (SI) and self-compatible (SC) sister taxa. In support of the hypothesis that pollinator-mediated selection integrates floral traits, we found that both SC Leavenworthia taxa have weaker overall floral correlations in comparison to sister taxa that rely upon pollinators. The two independently derived SC Leavenworthia flowers have significantly weaker stamen-petal or pistil-petal correlations, respectively, whereas the stamen-pistil correlation remains constant. These patterns suggest that relaxation of pollinator-mediated selection weakens the integration of traits associated with pollen export and import. The retention of high stamen-pistil correlations in the SC taxa of Leavenworthia further implies that the integration of these traits is either constrained or maintained by selection favoring the successful transfer of pollen within flowers to secure self-pollination.     

Variation in life-history traits among Urtica dioica populations with different history in parasitism by the holoparasitic plant Cuscuta europaea

Several studies demonstrate that natural enemies (e.g. parasites) have profound negative effects on the life-history traits of their hosts. If the host can compensate for the negative effects of parasitic infection by altering its life history, these modifications may partly form the basis of resistance or tolerance against parasites. Thus, parasites may be of considerable importance in shaping the evolution of life-history traits of their hosts. To examine if previous parasitism is associated with differences in life-history traits of the host, I conducted a common garden experiment with Urtica dioica plants originating from eight populations of which four were unparasitized, and four parasitized by the holoparasitic plant, Cuscuta europaea. A field survey indicated no differences between unparasitized and parasitized populations in, for example, the number of plant species and nutrient levels in the soil. Thus, it seems reasonable to assume that differences in life-history traits between the two population types in the common garden would reflect the effects of previous selection by the parasite. In the common garden, plants from parasitized populations started to flower later and allocated less biomass to asexual reproduction (measured as the production of stolons, i.e. clonal propagation) compared to plants from unparasitized populations. These results thus indicate that selection by the parasite may have favoured later onset of flowering, and may have selected against asexual reproduction.     

Categorizing locally rare plant taxa for conservation status

Locally rare taxa are those that are rare or uncommon within a local geographical boundary while more common outside of that boundary. In addition to the rare taxa identified by global, national, and state/provincial levels, locally rare taxa are important for the preservation of species diversity and ecological processes, and therefore require effective and recognizable conservation status. Currently, there are no specific local rarity criteria in use to categorize taxa at regional jurisdictional levels. To address this need, we developed criteria for categorizing locally rare plant taxa by using the framework the Natural Heritage Network’s Element Ranking System combined with attributes of the World Conservation Union’s Red List Criteria. We then tested the efficacy of our classification system (called L-ranks) on the flora of Napa County using a geographic information system and available plant distribution data for the State of California. Results indicated that 89 taxa from 34 families met the area of occupancy criteria for local rarity status. Our findings demonstrated that with available geographic data, the proposed criteria for classifying locally rare plants can be usefully applied at the county level to identify significant peripheral plant populations. The proposed L-rank system was specifically designed to be compatible with existing multi-scale conservation programs and will augment the current systems in use by local organizations. By systematically classifying locally rare plants, current regulations that are applicable to locally rare taxa may be used more effectively in conservation planning and prioritizing at the county scale.     

The elevational gradient of Andean plant endemism: varying influences of taxon-specific traits and topography at different taxonomic levels

Aim Little is known about the elevational gradient of plant endemism. It is mostly assumed that patterns are determined by topographical factors such as area of elevational belts and degree of habitat fragmentation, but comparative studies of different plant taxa along the same elevational gradient are lacking. The aim was to compare the elevational patterns of plant endemism of the entire flora and selected families and genera in a search for commonalities. Methods The elevational patterns of endemism for the entire Ecuadorean vascular plant flora, for twenty‐seven selected families, and for twenty‐four selected genera based on the Catalogue of Vascular Plants of Ecuador were analysed. Results Elevational patterns of endemism were non‐random at all taxonomic levels but there was no common elevational pattern. Rather, the study groups showed a wide variety of independent patterns at all taxonomic levels. Most groups had hump‐shaped patterns with maxima at different elevations and mostly at the same or at higher elevations than the maxima of species richness. The overall flora showed highest endemism in the narrowest and most fragmented elevational belts, presumably because of the consequent fragmentation of species populations. Main conclusions Patterns of endemism appear to be influenced both by taxon‐specific ecological traits (e.g. life form, reproduction, dispersal, demography, spatial population structure, competitive ability) in their specific interaction with historical processes and by environmental factors such as topographical fragmentation. The degree to which these influences become visible along the elevational gradient are determined by which combination of species is analysed: for a given genus or family, taxon‐specific traits dominate the patterns, for the entire flora taxon‐specific patterns are blurred by averaging and the signal of topography emerges. Beyond the elevational gradient as such, this study shows that the frequently stated assumption that given biogeographical settings lead to similar patterns of endemism among different taxa is wrong.     

Comparative floral and vegetative differentiation between two European Aquilegia taxa along a narrow contact zone

As a first step in determining the identity and relative importance of the evolutionary forces promoting the speciation process in two closely related European taxa of Aquilegia, we investigated the levels of morphological variation in floral and vegetative characters over the narrow region where their ranges enter into contact, and evaluate the relative importance of both types of traits in their differentiation. A total of 12 floral and ten vegetative characters were measured on 375 plants belonging to seven A. vulgaris populations and six A. pyrenaica subsp. cazorlensis populations located in southeastern Spain. Floral and vegetative morphological differentiation occur between taxa and among populations within taxa, but only vegetative characters (particularly plant height and leaf petiolule length) contribute significantly to the discrimination between taxa. Differentiation among populations within taxa is mostly explained by variation in floral traits. Consequently, morphological divergence between the two taxa cannot be interpreted as an extension of among-population differences occurring within taxa. Multivariate vegetative, but not floral, similarity between populations could be predicted from geographical distance. Moreover, the key role of certain vegetative traits in the differentiation of A. vulgaris and A. p. cazorlensis could possibly be attributable to the contrasting habitat requirements and stress tolerance strategies of the two taxa. These preliminary findings seem to disagree with the currently established view of the radiation process in the genus Aquilegia in North America, where the differentiation of floral traits seems to have played a more important role.     

Plant functional composition and ecosystem properties: the case of peatlands in South Africa

The assumption that ecosystems with similar emergent properties consist of similar functional groupings of plant species is tested by comparing three peatlands from different bioregions across South Africa. They are Mfabeni Swamp in the subtropical coastal region, Wakkerstroom on the inland plateau, and Goukou wetland in the Winter Rainfall region of the Western Cape. In each of the three peatlands, about 400 small vegetation plots have been made from which the abundance of each species per wetland can be assessed. The most dominant species in these plots have been investigated for 17 traits. The functional composition of the vegetation types has been compared across the three peatlands and Functional Diversity has been calculated, taking the dominance of each species into account. One peatland differed greatly from the other two, since the dominant species was of a functional type (“Palmiet/woody sedge”) that was very divergent from any other peatland species found in the study. This functional type can be considered an ecosystem engineer and the effects that this functional type has on the ecosystem results in the occurrence of many other functional types that do not occur in the other peatlands. When we consider emergent traits of an ecosystem as a function of all the plant functional traits that occur in that ecosystem, then peatlands can be regarded as a heterogeneous group of ecosystems. Even if emergent properties such as peat formation are similar between ecosystems, those ecosystems may still consist of very different functional groups. Ecosystem engineers have an impact on the final functional composition of an ecosystem and the degree in which ecosystem engineering plays a role in peatlands differs between different peatlands.     

The role of genetic constraints on the diversification of Iberian taxa of the genus Aquilegia (Ranunculaceae)

The microevolutionary process of adaptive phenotypic differentiation of quantitative traits between populations or closely‐related taxa depends on the response of populations to the action of natural selection. However, this response can be constrained by the structure of the matrix of additive genetic variance and covariance between traits in each population ( G matrix). In the present study, we obtained additive genetic variance and narrow sense heritability for 25 floral and vegetative traits of three subspecies of Aquilegia vulgaris, and one subspecies of Aquilegia pyrenaica through a common garden crossing experiment. For two vegetative and one floral trait, we also obtained the G matrix and genetic correlations between traits in each subspecies. The amount of genetic variation available in wild populations is not responsible for the larger differentiation of vegetative than floral traits found in this group of columbines. However, the low heritability of some traits constrained their evolution because phenotypic variability among taxa was larger for traits with larger heritability. We confirmed that the process of diversification of the studied taxa involved shifts in the G matrix, mainly determined by changes in the genetic covariance between floral and vegetative traits, probably caused by linkage disequilibrium in narrow endemic taxa. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 252–261.     

Integrating floral scent, pollination ecology and population genetics

1 . Floral scent is a key factor in the attraction of pollinators. Despite this, the role of floral scent in angiosperm speciation and evolution remains poorly understood. Modern population genetic approaches when combined with pollination ecology can open new opportunities for studying the evolutionary role of floral scent.
2 . A framework of six hypotheses for the application of population genetic tools to questions about the evolutionary role of floral scent is presented. When floral volatile chemistry is linked to pollinator attraction we can analyse questions such as: Does floral volatile composition reflect plant species boundaries? Can floral scent facilitate or suppress hybridization between taxa? Can the attraction of different pollinators influence plant mating systems and pollen-mediated gene flow? How is population genetic structure indirectly influenced by floral scent variation?
3 . The application of molecular tools in sexually deceptive orchids has confirmed that volatile composition reflects species boundaries, revealed the role of shared floral odour in enabling hybridization, confirmed that the sexual attraction mediated by floral odour has implications for pollen flow and population genetic structure and provided examples of pollinator-mediated selection on floral scent variation. Interdisciplinary studies to explore links between floral volatile variation, ecology and population genetics are rare in other plant groups.
4 . Ideal study systems for future floral scent research that incorporate population genetics will include closely related taxa that are morphologically similar, sympatric and co-flowering as well as groups that display wide variation in pollination mechanisms and floral volatiles.     

Population divergence along lines of genetic variance and covariance in the invasive plant Lythrum salicaria in eastern North America

Evolution during biological invasion may occur over contemporary timescales, but the rate of evolutionary change may be inhibited by a lack of standing genetic variation for ecologically relevant traits and by fitness trade-offs among them. The extent to which these genetic constraints limit the evolution of local adaptation during biological invasion has rarely been examined. To investigate genetic constraints on life-history traits, we measured standing genetic variance and covariance in 20 populations of the invasive plant purple loosestrife (Lythrum salicaria) sampled along a latitudinal climatic gradient in eastern North America and grown under uniform conditions in a glasshouse. Genetic variances within and among populations were significant for all traits; however, strong intercorrelations among measurements of seedling growth rate, time to reproductive maturity and adult size suggested that fitness trade-offs have constrained population divergence. Evidence to support this hypothesis was obtained from the genetic variance-covariance matrix (G) and the matrix of (co)variance among population means (D), which were 79.8% (95% C.I. 77.7-82.9%) similar. These results suggest that population divergence during invasive spread of L. salicaria in eastern North America has been constrained by strong genetic correlations among life-history traits, despite large amounts of standing genetic variation for individual traits.     

Divergent selection on flowering phenology but not on floral morphology between two closely related orchids

Closely related species often differ in traits that influence reproductive success, suggesting that divergent selection on such traits contribute to the maintenance of species boundaries. Gymnadenia conopsea ss. and Gymnadenia densiflora are two closely related, perennial orchid species that differ in (a) floral traits important for pollination, including flowering phenology, floral display, and spur length, and (b) dominant pollinators. If plant–pollinator interactions contribute to the maintenance of trait differences between these two taxa, we expect current divergent selection on flowering phenology and floral morphology between the two species. We quantified phenotypic selection via female fitness in one year on flowering start, three floral display traits (plant height, number of flowers, and corolla size) and spur length, in six populations of G. conopsea s.s. and in four populations of G. densiflora. There was indication of divergent selection on flowering start in the expected direction, with selection for earlier flowering in two populations of the early‐flowering G. conopsea s.s. and for later flowering in one population of the late‐flowering G. densiflora. No divergent selection on floral morphology was detected, and there was no significant stabilizing selection on any trait in the two species. The results suggest ongoing adaptive differentiation of flowering phenology, strengthening this premating reproductive barrier between the two species. Synthesis: This study is among the first to test whether divergent selection on floral traits contribute to the maintenance of species differences between closely related plants. Phenological isolation confers a substantial potential for reproductive isolation, and divergent selection on flowering time can thus greatly influence reproductive isolation and adaptive differentiation.     

CONSEQUENCES OF FLORAL VARIATION FOR MALE AND FEMALE REPRODUCTION IN EXPERIMENTAL POPULATIONS OF WILD RADISH,RAPHANUS SATIVUS L

We documented effects of floral variation on seed paternity and maternal fecundity in a series of small experimental populations of wild radish, R. sativus. Each population was composed of two competing pollen donor groups with contrasting floral morphologies and several designated maternal plants. Progeny testing with electrophoretic markers allowed us to measure paternal success. Realized fecundity by each maternal plant and the fraction of those seeds attributable to each pollen donor group were used as outcome variables in path analysis to explore relationships between floral characters (petal size, pollen grain number per flower, and modal pollen grain size), pollinator visitation patterns, and reproductive success. A wide range of pollinator taxa visited the experimental populations, and patterns of discrimination appeared to vary among them. The impact of visitation on male and female reproduction also varied among taxa; visits of small native bees significantly increased paternal success, while those of honey bees reduced male fitness. Only visits by large native bees had discernible effects on recipient fecundity, and, overall, fecundity was not limited by visitation. Maternal plants bearing large-petalled flowers produced fewer flowers during the experiment, reducing their total seed production. In these small populations, postpollination processes (at least in part, compatibility) significantly influenced male and female reproductive success. Variation in pollinator pools occurring on both spatial and temporal scales may act to preserve genetic variation for floral traits in this species.