Corolla Tube Length Research Articles

Is there spatial variation in phenotypic selection on floral traits in a generalist plant–pollinator system?

The selective role of pollinators on the floral phenotype has been identified as the main force behind angiosperm diversification. However, in generalized plant–pollinator interactions this association may not be that evident, since pollinator assemblages vary in composition among populations, possibly influencing the direction and intensity of floral trait selection. In this study we determine whether there was spatial variation in pollinator assemblages and the selective forces they exert in ten populations of Alstroemeria ligtu var. simsii. We characterized the whole pollinator assemblage in ten populations, quantified four floral attraction traits and determined potential selection targets in each of the study populations. Our results revealed that populations differed in the composition of their pollinator assemblages, and the pollinators with the highest visitation rates also differed among populations. Using phenotypic selection analysis we detected significant differentials and selection gradients only in two of the ten populations, for corolla tube length and ratio of the nectar guide. The spatial variation in selection showed that linear selection acting upon these traits differed significantly among the studied populations. Our study indicates that selection can be detected in generalized plant–pollinator systems and brings new evidence of phenotypic selection variation in space for this endemic plant species. Future studies are needed to determine whether the selective patterns described here are consistent over time and whether they produce evolutionary change in the populations under study.

Studies on floral morphology and biology in Jasminum spp.

The present investigation was carried out to study the floral morphology and biology of 5 genotypes during 2016-17. Many flowered cymes both terminal and axillary were observed in J. auriculatum and J. grandiflorum; whereas, cluster bearing flowers in terminal position were observed in J. multiflorum (IIHR JM–1 and IIHR JM–2), J. calophyllum, J. flexile and J. malabaricum. Flower bud was pointed and long in all genotypes; its colour was either green white (157 B) or white (155 C) or white (155 D).Tinge on flower bud was observed in J. grandiflorum (CO.1 Pitchi and Arka Surabhi), J. rigidum, J. nitidum and J. malabaricum. Flower petal tip was either sharp or blunt and flower colour on opening was either white (155 C) or white (155 D) or white with pinkish underneath (155 D) in all the genotypes. Among the 15 genotypes, J. grandiflorum var. CO.1 Pitchi recorded longest flower bud length (4.81 cm) and corolla tube length (2.92 cm); however, maximum corolla length was recorded in J. nitidum (2.15 cm). Maximum number of forks per cymes was recorded in J. auriculatum var. CO.1 Mullai (40.13). Maximum number (6.51) and length of calyx lobe (1.28 cm) was recorded in J. multiflorum –IIHRJM-2 and J. nitidum, respectively. Flower diameter ranged from 1.74 (J. auriculatum-IIHRJA-2) to 4.93 cm (J. nitidum), whereas number of petals varied from 4.97 (J. grandiflorum var. CO.1 Pitchi) to 10.67 (J. nitidum). All genotypes recorded one style per pistil and its length varied from 0.42 cm (J. auriculatum var. CO.2 Mullai) to 2.32 cm (J. grandiflorum var. CO.1 Pitchi). Anthesis and anther dehiscence was recorded earlier in summer months, while, it was delayed during cooler months. However, the peak anthesis was observed from 6:00 to 7:00 p.m. and anther dehiscence from 4:00 to 7:00 p.m. The earliest anthesis was observed in J. auriculatum genotypes and anther dehiscence was observed in J. auriculatum and J. multiflorum genotypes. The stigma was receptive 12 h before an thesis and up to 24 h of anthesis. The maximum receptivity was observed from the time of anthesis to 12 h after anthesis.

A comparison of coffee floral traits under two different agricultural practices

Floral traits and rewards are important in mediating interactions between plants and pollinators. Agricultural management practices can affect abiotic factors known to influence floral traits; however, our understanding of the links between agricultural practices and floral trait expression is still poorly understood. Variation in floral morphological, nectar, and pollen traits of two important agricultural species, Coffea arabica and C. canephora, was assessed under different agricultural practices (sun and shade). Corolla diameter and corolla tube length were larger and pollen total nitrogen content greater in shade plantations of C. canephora than sun plantations. Corolla tube length and anther filament length were larger in shade plantations of C. arabica. No effect of agricultural practice was found on nectar volume, sugar or caffeine concentrations, or pollen production. Pollen total nitrogen content was lower in sun than shade plantations of C. canephora, but no difference was found between sun and shade for C. arabica. This study provides baseline data on the influence of agronomic practices on C. arabica and C. canephora floral traits and also helps fill a gap in knowledge about the effects of shade trees on floral traits, which can be pertinent to other agroforestry systems.

Early consequences of allopolyploidy alter floral evolution in Nicotiana (Solanaceae)

BackgroundPolyploidy has played a major role in angiosperm evolution. Previous studies have examined polyploid phenotypes in comparison to their extant progenitors, but not in context of predicted progenitor phenotypes at allopolyploid origin. In addition, differences in the trends of polyploid versus diploid evolution have not been investigated. We use ancestral character-state reconstructions to estimate progenitor phenotype at allopolyploid origin to determine patterns of polyploid evolution leading to morphology of the extant species. We also compare trends in diploid versus allopolyploid evolution to determine if polyploidy modifies floral evolutionary patterns.ResultsPredicting the ancestral phenotype of a nascent allopolyploid from reconstructions of diploid phenotypes at the time of polyploid formation generates different phenotype predictions than when extant diploid phenotypes are used, the outcome of which can alter conclusions about polyploid evolution; however, most analyses yield the same results. Using ancestral reconstructions of diploid floral phenotypes indicate that young polyploids evolve shorter, wider corolla tubes, but older polyploids and diploids do not show any detectable evolutionary trends. Lability of the traits examined (floral shape, corolla tube length, and corolla tube width) differs across young and older polyploids and diploids. Corolla length is more evolutionarily labile in older polyploids and diploids. Polyploids do not display unique suites of floral characters based on both morphological and color traits, but some suites of characters may be evolving together and seem to have arisen multiple times within Nicotiana, perhaps due to the influence of pollinators.ConclusionsYoung polyploids display different trends in floral evolution (shorter, wider corolla tubes, which may result in more generalist pollination) than older polyploids and diploids, suggesting that patterns of divergence are impacted by the early consequences of allopolyploidy, perhaps arising from genomic shock and/or subsequent genome stabilization associated with diploidization. Convergent evolution in floral morphology and color in Nicotiana can be consistent with pollinator preferences, suggesting that pollinators may have shaped floral evolution in Nicotiana.

Morphospace exploration reveals divergent fitness optima between plants and pollinators.

The obligate mutualism and exquisite specificity of many plant-pollinator interactions lead to the expectation that flower phenotypes (e.g., corolla tube length) and corresponding pollinator traits (e.g., hawkmoth proboscis length) are congruent as a result of coevolution by natural selection. However, the effect of variation in flower morphology on the fitness of plants and their pollinators has not been quantified systematically. In this study, we employed the theoretical morphospace paradigm using a combination of 3D printing, electronic sensing, and machine vision technologies to determine the influence of two flower morphological features (corolla curvature and nectary diameter) on the fitness of both parties: the artificial flower and its hawkmoth pollinator. Contrary to the expectation that the same flower morphology maximizes the fitness of both plant and pollinator, we found that the two parties have divergent optima for corolla curvature, with non-overlapping fitness peaks in flower morphospace. The divergent fitness optima between plants and pollinators could lead to evolutionary diversification in both groups.

Crescendo, diminuendo and subito of the trumpets: winds of change in the concerted evolution between flowers and pollinators in Salpichroa (Solanaceae)

‘Gradual’ vs ‘punctuated’ and ‘unidirectional’ (only lengthening) vs. ‘bidirectional’(lengthenings and shortenings) modes of evolution are explanations that compete to explain adaptive changes of flower tube length in angiosperm. The nightshade genus Salpichroa Miers, with 21 species mostly growing in the tropical Andes of southern South America, has the opportune qualities of including nearly 15-fold inter-specific variation in corolla tube length, as well as one species that is a candidate for participating in evolutionary escalation with the longest-billed hummingbird, Ensifera ensifera. We reconstructed the phylogenetic relationships using five molecular markers, the two plastid markers trnD-trnT and trnL, and three nuclear markers, ITS and two COSII, and estimated divergence times of the genus in order to reconstruct the history of both corolla tube length and pollination mode (i.e. hummingbirds, moths or multiple). We used comparative methods to determine whether corolla tube elongation/shortening is associated with shifts in pollination mode and to test, modes and rates of corolla tube change. We found evidence of both lengthening and shortening of corolla tubes. Evolutionary rates are consistent with rapid corolla tube length transitions that are only partly associated with shifts in pollination mode. Though ‘punctuated’ evolution (i.e. large changes predominantly at speciation events) explained corolla changes in the whole genus, ‘gradual’ evolution (i.e. gradual changes during a coevolutionary race with the same pollinator) was a better explanation for the change in the long-flowered clade, mostly pollinated by hummingbirds.

The relative strength of different floral visitors driving floral evolution within a Primula secundiflora population

Floral visitor assemblages within plant populations are usually composed of different visitors, and the relative abundance of these visitors also varies. Therefore, identifying the relative strength of these floral visitors driving floral evolution within the population is an important step in predicting the evolutionary trajectory of floral traits. Using supplemental hand pollination and nectar-robbing exclusion treatments, we experimentally identified the relative strengths of legitimate pollinators (that visit flowers through the corolla tube entrance) and nectar robbers (that visit flowers by biting a hole in the corolla tube or using an existing hole) driving floral evolution within the Primula secundiflora population. We also estimated legitimate pollinator- and nectar robber-mediated selection separately for pin and thrum flowers. Both legitimate pollinators and nectar robbers mediated selection on pollination efficiency traits in P. secundiflora population. Legitimate pollinators mediated selection for wider corolla tubes, whereas nectar robbers mediated selection for longer corolla tubes. In addition, nectar robber-mediated selection on corolla tube length marginally varied between the pin and thrum flowers. Nectar robber mediated selection for longer corolla tube length in the pin flowers not in the thrum flowers. These results indicate that legitimate pollinators and nectar robbers within a population can drive differential evolutionary trajectories of floral traits.

Pollinator-mediated selection on floral traits varies in space and between morphs in Primula secundiflora.

Elucidating how variation in selection shapes the evolution of flowers is key to understanding adaptive differentiation processes. We estimated pollinator-mediated selection through female function in L-morph (long-style and short-anther phenotype) and S-morph (short-style and long-anther phenotype) flowers among four Primula secundiflora populations with different pollinator assemblages. Variation in pollinator assemblage strongly contributed to differences in reproductive success among populations and between morphs of the primrose species. A wider corolla tube width was selected in the bumblebee-dominated populations, whereas shorter corolla tube length and wider corolla tube width were selected in the syrphid fly-dominated populations. Morph-specific variation in pollinator-mediated selection on corolla tube length was detected in the syrphid fly-dominated populations. A shorter corolla tube was selected in the L-morph flowers. However, similar selective pressure on this trait was not observed in the S-morph flowers. These results show that variation in pollinator assemblage leads to variation in selection in space and between morphs. The findings highlight the potential forces of different pollinator agents in driving floral evolution in this primrose species.

A new “giant” species of Maranta L. (Marantaceae) from the Atlantic Forest of northeastern Brazil

A new species of Maranta subg. Maranta, M. gigantea, is described and illustrated. This is known from the submontane Atlantic Forest in the states of Pernambuco and Alagoas (Brazil). Based on the zingiberoid growth form it is morphologically similar to M. anderssoniana and M. zingiberina, differing mainly in the shape of the leaf blade (lanceolate to oblong or ovate respectively vs. narrow-lanceolate) and number of calli in the callose staminode (one prominent callus vs. two prominent calli). It is further differentiated from M. anderssoniana by being larger plants (up to 1.8 m tall vs. up to 1.0 m tall), with a tomentose leaf sheath (vs. sericeous), larger corolla tube length (9−12 mm long vs. 5−6 mm long), asymmetrically elliptical corolla lobes (vs. asymmetrically oblong) and larger outer staminodes (minor 12−15 × 6.5−8 mm vs. 10−11 × 5.5−6 mm and major 13−16 × 8.5 × 10.5 mm vs. 10−12 × 8−9.2 mm). Due to its narrow distribution, it is classified as critically endangered.

Flower colour preferences of Aporia bieti (Lepidoptera: Pieridae) in the Xiama Forest Farm, Gansu, China

In addition to their ornamental value, butterflies provide value to flowering plants through pollination, which can improve their heterosis. Studying the relationship between butterflies and flowers is useful for understanding the adaptive relationship between them. By observing the pollinating and feeding behaviour of Aporia bieti in the Xiama forest, Gansu, we explored the adaptive relationship between A. bieti proboscis size and the corolla tube length of the flowers. To eliminate interference from the butterfly's sense of smell, we used foam flowers instead of real flowers. The results indicated that (1) of the red, yellow, pink, purple, and white flowers tested, yellow flowers were preferred; (2) there was no distinct difference in the preferences of A. bieti for large- (45mm) and small- (25mm) sized flowers; and (3) A. bieti proboscis length was significantly related to the corolla tube length of the flowers fed on by the butterfly, which suggests co-evolution between butterfly proboscis length and the length of the pollen tube.

Phenotypic plasticity of floral traits and pollination adaption in an alpine plant Pedicularis siphonantha D. Don when transplanted from higher to lower elevation in Eastern Himalaya

Phenotypic plasticity and/or pollinator-mediated selection may be responsible for the changes in floral traits of plants when they are forced to live in new conditions. Although the two events could be independent, we hypothesized that phenotypic plasticity in floral traits might help to coordinate plant-pollinator interactions and enhance plant reproductive success in changing habitats. To test this hypothesis, we investigated floral traits and pollination on three natural populations of a lousewort (Pedicularis siphonantha) ranging at different elevations, as well as two downward transplanted populations in Shangeri-La County and Deqin County, northwest Yunnan, China. The results indicated that floral traits, i.e. phenology, longevity, display size, corolla tube length and pollen production differed significantly among populations. Moreover, or the two transplanted populations, floral traits diverged from their original populations, but converged to their host populations. Although the phenotypic plasticity in floral traits might be a rapid response to abiotic factor such as warmer environment, the changes in floral traits were found to be well adapted to pollination environment of the host population. Compared with plants of their original habitats in higher elevation, the transplanted individuals advanced flowering time, shortened flower longevity, reduced floral display size and pollen production, received higher visiting frequency and yielded more seeds. These findings suggested that phenotypic plasticity of floral traits might help plants adjust their resource allocation strategy between preand post-pollination stages in response to harsh or temperate conditions, which might correspondingly meet a pollinator-poor or hyphen rich environment. This would be beneficial for the widely-distributed species to adapt to various environmental changes.

Interspecific and intraspecific variation in corolla tube length in Pedicularis species achieved by both cell anisotropy and division

AbstractThe association between plants with long corolla tubes and pollinators with long tongues has evolved repeatedly in diverse pollination systems. However, the morphogenesis of long corolla tubes involved in diverse plant groups remains largely unexplored, limiting our understanding of the evolution and maintenance of long corolla tubes. Corolla tubes of Himalayan Pedicularis species exhibit striking length diversity, ranging from less than 10 mm to more than 120 mm. We investigated the role of cell division and cell expansion in determining the corolla tube morphology in eight Pedicularis species and in an experimental population of P. siphonantha Don in which corolla tubes were elongated under shading and watering treatments. Among species, the corolla tube length was positively correlated with both cell number and cell length but not cell width. Our analyses of intraspecific variation in corolla tube length indicated that it was positively correlated with cell length in all eight species but with cell number in only four of the species, indicating that corolla tube development in Pedicularis generally involves anisotropic cell expansion. The elongation of corolla tubes in P. siphonantha under experimental conditions was caused by the anisotropic elongation of cells; cell number of tube‐elongated flowers was not significantly increased. Our results showed that intraspecific variation in corolla tube length in Pedicularis species was largely attributable to changes in cell anisotropy, but the evolutionary innovation underlying the rapid radiation of Pedicularis corolla tubes was attributable to both cell division and cell expansion.

Agastache sandersiana (Lamiaceae): A new species from northwestern Durango, Mexico

Abstract We describe and illustrate Agastache sandersiana as a new species from northwestern Durango. This is a narrow endemic that clearly differs from all other species in the genus by leaf size, shape, and pubescence; inflorescence architecture; calyx tube length; corolla color; and corolla tube length. Additionally, an identification key to the Agastache species occurring in Durango, Mexico is provided.

Natural history matters: how biological constraints shape diversified interactions in pollination networks.

Species-specific traits constrain the ways organisms interact in nature. Some pairwise interactions among coexisting species simply do not occur; they are impossible to observe despite the fact that partners coexist in the same place. The author discusses these 'forbidden links' of species interaction networks. Photo: a sphingid moth, Manduca sexta visiting a flower of Tocoyena formosa (Rubiaceae) in the Brazilian Cerrado; tongue and corolla tube lengths approximately 100 mm. Courtesy of Felipe Amorim. Sazatornil, F.D., Moré, M., Benitez-Vieyra, S., Cocucci, A.A., Kitching, I.J., Schlumpberger, B.O., Oliveira, P.E., Sazima, M. & Amorim, F.W. (2016) Beyond neutral and forbidden links: morphological matches and the assembly of mutualistic hawkmoth-plant networks. Journal of Animal Ecology, 85, 1586-1594. Species-specific traits and life-history characteristics constrain the ways organisms interact in nature. For example, gape-limited predators are constrained in the sizes of prey they can handle and efficiently consume. When we consider the ubiquity of such constrains, it is evident how hard it can be to be a generalist partner in ecological interactions: a free-living animal or plant cannot simply interact with every available partner it encounters. Some pairwise interactions among coexisting species simply do not occur; they are impossible to observe despite the fact that partners coexist in the same place. Sazatornil etal. () explore the nature of such constraints in the mutualisms among hawkmoths and the plants they pollinate. In this iconic interaction, used by Darwin and Wallace to vividly illustrate the power of natural selection in shaping evolutionary change, both pollinators and plants are sharply constrained in their interaction modes and outcomes.

Jasminanthes xuanlienensis (Apocynaceae, Asclepiadoideae), a new species from Vietnam.

Jasminanthes xuanlienensis (Apocynaceae, Asclepiadoideae), a new species from Vietnam is described, illustrated and compared with its five congeners. Jasminanthes xuanlienensis differs distinctly from congeners by the longer peduncles (14–18 cm vs. 4 cm at most in Jasminanthes pilosa and Jasminanthes saxatilis, salmon-pink color of the inner corolla lobes (white or greenish in the other species), and corolla tube length (12.0–14.5 mm vs. shorter or longer in congeners).

Adaptive differentiation in floral traits in the presence of high gene flow in scarlet gilia (Ipomopsis aggregata).

Plant-pollinator interactions are thought to be major drivers of floral trait diversity. However, the relative importance of divergent pollinator-mediated selection vs. neutral processes in floral character evolution has rarely been explored. We tested for adaptive floral trait evolution by comparing differentiation at neutral genetic loci to differentiation at quantitative floral traits in a putative Ipomopsis aggregata hybrid zone. Typical I.aggregata subsp. candida displays slender white tubular flowers that are typical of flowers pollinated by hawkmoths, and subsp. collina displays robust red tubular flowers typical of flowers pollinated by hummingbirds; yet, hybrid flower morphs are abundant across the East Slope of the Colorado Rockies. We estimated genetic differentiation (FST ) for nuclear and chloroplast microsatellite loci and used a half-sib design to calculate quantitative trait divergence (QST ) from collection sites across the morphological hybrid zone. We found little evidence for population structure and estimated mean FST to be 0.032. QST values for several floral traits including corolla tube length and width, colour, and nectar volume were large and significantly greater than mean FST . We performed multivariate comparisons of neutral loci to genetic correlations within and between populations and found a strong signal for divergent selection, suggesting that specific combinations of floral display and reward traits may be the targets of selection. Our results show little support for historical subspecies categories, yet floral traits are more diverged than expected due to drift alone. Non-neutral divergence for multivariate quantitative traits suggests that selection by pollinators is maintaining a correlation between display and reward traits.

Coevolutionary elaboration of pollination-related traits in an alpine ginger (Roscoea purpurea) and a tabanid fly in the Nepalese Himalayas.

Geographical variation in the interacting traits of plant-pollinator mutualism can lead to local adaptive differentiation. We tested Darwin's hypothesis of reciprocal selection as a key driving force for the evolution of floral traits of an alpine ginger (Roscoea purpurea) and proboscis length of a tabanid fly (Philoliche longirostris). We documented the pattern of trait variation in R.purpurea and P.longirostris across five populations.At each site, we quantified pollinator-mediated selection on floral display area, inflorescence height and corolla length of R.purpurea by comparing selection gradients for flowers exposed to natural pollination and to supplemental hand pollination. Reciprocal selection between plant and fly was examined at two sites via the relationship between proboscis length and nectar consumption (fly benefit) and corolla length and pollen deposition (plant benefit). Local corolla tube length was correlated with local fly proboscis length among the five sites. We found strong linear selection imposed by pollinators on corolla tube length at all sites, but there was no consistent relationship of fitness to inflorescence height or floral display area. Selection between corolla length and proboscis length was reciprocal at the two experimental sites examined. The geographical pattern of trait variation and the evidence of selection is consistent with a mosaic of local, species-specific reciprocal selection acting as the major driving force for the evolution of corolla length of R.purpurea and proboscis length of P.longirostris.

Are long corolla tubes in Pedicularis driven by pollinator selection?

The evolution of long corolla tubes has been hypothesized to be driven by long-tongued pollinators. Corolla tubes in Pedicularis species can be longer than 10 cm which may function as flower stalks to increase visual attractiveness to pollinators because these species provide no nectar and are pollinated by bumblebees. The corolla tube length was manipulated (shorter or longer) in two Pedicularis species in field to examine whether longer tubes are more attractive to pollinators and produce more seeds than short tubes. Our results did not support the pollinator attraction hypothesis, leaving the evolution of long tubes in Pedicularis remains mysterious.

Nectarless flowers with deep corolla tubes inPedicularis: does long pistil length provide an arena for male competition?

Pollinator-mediated selection does not seem to have a direct influence on the evolution of a long corolla tube in a nectarless flower. We hypothesized that the long pistil length of the nectarless flower with a deep corolla tube provided an opportunity for male competition. Pedicularis siphonantha, a nectarless and partially self-incompatible lousewort with substantial variation in corolla tube length, was used to test the hypothesis. We tested whether and how corolla tube length affected seed production per capsule and seed germination rate with different pollination treatments. Flowers were hand-pollinated with pollen from one self donor and one outcross donor and mixed pollen grains consisting of equal amounts from the two donor types, respectively. Additionally, seeds from open-pollinated flowers with different corolla tube lengths were collected separately for measurement of germination rate. Pollination treatment and corolla tube length significantly affected number of seeds per capsule. Moreover, a significant positive relationship between seeds per capsule and corolla tube length was found when mixed hand pollination was conducted. Seeds of self hand-pollinated flowers had a lower germination rate than those from outcross-pollinated flowers. Under open pollination, seeds from flowers with longer corolla tubes tended to have higher germination rate. In P. siphonantha, outcross pollen may have a higher probability of contributing to the next generation when transferred to flowers with longer corolla tubes. The pistil length, therefore, should be seen as a female choice mechanism, which provides an arena for male-to-male competition. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179, 526–532.

Long corollas as nectar barriers in Lonicera implexa: interactions between corolla tube length and nectar volume

Long corollas are a classical example of nectar barriers, because they prevent undesired visitors from consuming the reward intended for more effective pollinators. As the investment in nectar barriers increases, flower attractiveness and nectar rewards may also increase to maintain loyal visitation of most effective pollinators; and flowers may become more prone to nectar robbing. We evaluated the effect of nectar barriers (corolla tube length), two related traits (nectar volume and upper lip size) and the associated risk of nectar robbing, on the fecundity of Lonicera implexa plants from three populations differing in the abundance of its most efficient pollinator, the hummingbird hawkmoth Macroglossum stellatarum. Corolla tube length varied most among individuals within populations (45–46 % of total variance) and inflorescences within individuals (23–32 %), and showed little variation among populations (0.2–11 %). Longer corolla tubes were always associated with larger nectar volumes and larger upper lips, although the strength of the relationships varied across populations and years. Robbing frequency increased with corolla tube length, decreased with nectar volume and upper lip size, and its weak effects on fecundity were predominantly positive. Plant fecundity peaked at two different optima: long corollas with little nectar and short corollas with abundant nectar. However, the exact shape of the interaction between corolla length and nectar volume, as well as the combination of traits showing the highest fecundity, differed between populations and years. This variation could be explained by among-population differences in pollinator assemblages, and inter-annual changes in resources dedicated to reproduction. Our study shows that large nectar volumes can modulate the effect of corolla length as a nectar barrier, and that the combination of these two traits that maximises fecundity may be related to the identity of pollinators within each population.