Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 66
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Plant Res ; 132(4): 499-507, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31228016

RESUMO

Extrafloral nectary (EFN)-bearing plants attract ants to gain protection against herbivores. Some EFN-bearing plants possess different types of EFNs, which might have different effects on ants on the plants. Mallotus japonicus (Thunb.) Muell. Arg. (Euphorbiaceae) bears two types of EFNs, including a pair of large EFNs at the leaf base and many small EFNs along the leaf edge. This study aimed to determine the different roles of the two types of EFNs in biotic defense by ants. A field experiment was conducted to investigate the effect of leaf damage on EFN production and on the distribution pattern of ants. After leaf damage, the number of leaf edge EFNs increased in the leaves first-produced. The number of ants on the leaves also increased, and the foraging area of ants extended from the leaf base to the leaf tip. An EFN-covering field experiment revealed that leaf edge EFNs had a greater effect than leaf base EFNs on ant dispersal on leaves. The extended foraging area of ants resulted in an increase of encounter or attack rate against an experimentally placed herbivore, Spodoptera litura. These results suggest that M. japonicus plants control the foraging area of ants on their leaves using different types of EFNs in response to leaf damage, thus achieving a very effective biotic defense against herbivores by ants.


Assuntos
Formigas , Mallotus (Planta)/fisiologia , Folhas de Planta/fisiologia , Néctar de Plantas/fisiologia , Animais , Herbivoria , Mallotus (Planta)/anatomia & histologia , Folhas de Planta/anatomia & histologia , Spodoptera
2.
Plant Biol (Stuttg) ; 21(5): 967-974, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31050864

RESUMO

The trait-fitness relationship influences the strength and direction of floral evolution. To fully understand and predict the evolutionary trajectories of floral traits, it is critical to disentangle the direct and indirect effects of floral traits on plant fitness in natural populations. We experimentally quantified phenotypic selection on floral traits through female fitness and estimated the casual effects of nectar robbing with different nectar robbing intensities on trait-fitness relationships in both the L- (long-style and short-anther phenotype) and S-morph (short-style and long-anther phenotype) flowers among Primula secundiflora populations. A larger number of flowers and wider corolla tubes had both direct and indirect positive effects on female fitness in the P. secundiflora populations. The indirect effects of these two traits on female fitness were mediated by nectar robbers. The indirect effect of the number of flowers on female fitness increased with increasing nectar robbing intensity. In most populations, the direct and/or indirect effects of floral traits on female fitness were stronger in the S-morph flowers than in the L-morph flowers. In addition, nectar robbers had a direct positive effect on female fitness, but this effect varied between the L- and S-morph flowers. These results show the potential role of nectar robbers in influencing the trait-fitness relationships in this primrose species.


Assuntos
Flores/anatomia & histologia , Aptidão Genética , Néctar de Plantas , Primula/anatomia & histologia , Flores/fisiologia , Aptidão Genética/fisiologia , Fenótipo , Néctar de Plantas/fisiologia , Polinização/fisiologia , Primula/fisiologia
3.
Planta ; 250(1): 263-279, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31020407

RESUMO

MAIN CONCLUSION: Sugars (glucose, fructose and sucrose), as well as proteogenic and non-proteogenic amino acids, are present in the nectar of Platanthera bifolia and P. chlorantha. Nectar quantity and quality are floral traits that are subjected to pollinator-mediated selection. Nectar sugar and amino acid (AA) composition in two sister species, P. bifolia and P. chlorantha, was analysed and the interspecies differences in nectar and the importance of these nectar characteristics for reproductive success were investigated. Nectar was collected from four P. bifolia and three P. chlorantha populations that exist in different habitats in three regions of NE Poland. Nectar from about 30 flowers (from each population) was sampled and analysed using high-performance liquid chromatography. We found the same primary sugars and AA components in the nectar of both species, although their content varied between the populations according to habitat properties. The nectar of P. bifolia and P. chlorantha both had low sugar concentrations (9.04-20.68%) and were dominated by hexoses, with sucrose:hexoses ratios between 0.03 and 0.31 across the different populations (the average for the P. bifolia populations was 0.17 and the average for the P. chlorantha populations was - 0.05). Total sugar content did not influence reproductive success and we found positive selection on fructose content. In general, 23 different AAs were detected in both Platanthera species. Cysteine and γ-aminobutyric acid were present in only one population of P. chlorantha. Sarcosine dominated among the non-proteogenic AAs. To our knowledge, this is the first report that characterizes the sugar and AA profiles in the nectar of P. bifolia and P. chlorantha in natural populations in the context of effectiveness of reproduction. Total AAs negatively influenced male reproductive success (r = - 0.79). Pollinators of the investigated species were found to be sensitive to the AAs' taste, from taste classes I and IV. Correlation between male reproductive success and the content of AAs from these groups was 0.79 in both cases. In this manuscript, we investigated the characteristics of P. bifolia and P. chlorantha nectar, and compared these characteristics to the available data in the context of their adaptations to the requirements of pollinators and with regard to the importance of nectar quality for reproductive success of the studied species.


Assuntos
Mariposas/fisiologia , Orchidaceae/química , Néctar de Plantas/química , Aminoácidos/análise , Animais , Ecossistema , Flores/química , Flores/fisiologia , Frutose/análise , Glucose/análise , Orchidaceae/fisiologia , Néctar de Plantas/fisiologia , Polônia , Polinização , Reprodução , Sacarose/análise
4.
Plant Biol (Stuttg) ; 21(4): 738-744, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30773824

RESUMO

Most angiosperms rely on animal pollination for reproduction, but the dependence on specific pollinator groups varies greatly between species and localities. Notably, such dependence may be influenced by both floral traits and environmental conditions. Despite its importance, their joint contribution has rarely been studied at the assemblage level. At two elevations on the Caribbean island of Dominica, we measured the floral traits and the relative contributions of insects versus hummingbirds as pollinators of plants in the Rubiaceae family. Pollinator importance was measured as visitation rate (VR) and single visit pollen deposition (SVD), which were combined to assess overall pollinator effectiveness (PE). In the wet and cool Dominican highland, we found that hummingbirds were relatively more frequent and effective pollinators than insects, whereas insects and hummingbirds were equally frequent and effective pollinators at the warmer and less rainy midelevation. Furthermore, floral traits correlated independently of environment with the relative importance of pollinators, hummingbirds being more important in plant species having flowers with long and wide corollas producing higher volumes of dilute nectar. Our findings show that both environmental conditions and floral traits influence whether insects or hummingbirds are the most important pollinators of plants in the Rubiaceae family, highlighting the complexity of plant-pollinator systems.


Assuntos
Aves , Insetos , Polinização , Rubiaceae/fisiologia , Altitude , Animais , Aves/fisiologia , Dominica , Flores/anatomia & histologia , Flores/fisiologia , Umidade , Insetos/fisiologia , Néctar de Plantas/fisiologia , Rubiaceae/anatomia & histologia , Temperatura
5.
PLoS One ; 14(2): e0211855, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30811515

RESUMO

Mutualistic interactions are powerful drivers of biodiversity on Earth that can be represented as complex interaction networks that vary in connection pattern and intensity. One of the most fascinating mutualisms is the interaction between hummingbirds and the plants they visit. We conducted an exhaustive search for articles, theses, reports, and personal communications with researchers (unpublished data) documenting hummingbird visits to flowers of nectar-rewarding plants. Based on information gathered from 4532 interactions between 292 hummingbird species and 1287 plant species, we built an interaction network between nine hummingbird clades and 100 plant families used by hummingbirds as nectar resources at a continental scale. We explored the network architecture, including phylogenetic, morphological, biogeographical, and distributional information. As expected, the network between hummingbirds and their nectar plants was heterogeneous and nested, but not modular. When we incorporated ecological and historical information in the network nodes, we found a generalization gradient in hummingbird morphology and interaction patterns. The hummingbird clades that most recently diversified in North America acted as generalist nodes and visited flowers with ornithophilous, intermediate and non-ornithophilous morphologies, connecting a high diversity of plant families. This pattern was favored by intermediate morphologies (bill, wing, and body size) and by the low niche conservatism in these clades compared to the oldest clades that diversified in South America. Our work is the first effort exploring the hummingbird-plant mutualistic network at a continental scale using hummingbird clades and plant families as nodes, offering an alternative approach to exploring the ecological and evolutionary factors that explain plant-animal interactions at a large scale.


Assuntos
Aves/fisiologia , Comportamento Alimentar/fisiologia , Néctar de Plantas/fisiologia , Fenômenos Fisiológicos Vegetais , Animais , Biodiversidade , Tamanho Corporal , Flores/fisiologia , Polinização/fisiologia , Estações do Ano , América do Sul , Especialização , Simbiose/genética
6.
Plant Biol (Stuttg) ; 21(4): 732-737, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30636362

RESUMO

It has been hypothesised that intense metabolism of nectar-inhabiting yeasts (NIY) may change nectar chemistry, including volatile profile, which may affect pollinator foraging behaviours and consequently plant fitness. However, empirical evidence for the plant-microbe-pollinator interactions remains little known. To test this hypothesis, we use a bumblebee-pollinated vine Clematis akebioides endemic to southwest China as an experimental model plant. To quantify the incidence and density of Metschnikowia reukaufii, a cosmopolitan NIY in floral nectar, a combination of yeast cultivation and microscopic cell-counting method was used. To examine the effects of NIY on plant-pollinator interactions, we used real flowers filled with artificial nectar with or without yeast cells. Then the volatile metabolites produced in the yeast-inoculated nectar were analysed with coupled gas chromatography and mass spectrometry (GC-MS). On average 79.3% of the C. akebioides flowers harboured M. reukaufii, and cell density of NIY was high to 7.4 × 104 cells mm-3 . In the field population, the presence of NIY in flowers of C. akebioides increased bumblebee (Bombus friseanus) pollinator visitation rate and consequently seed set per flower. A variety of fatty acid derivatives produced by M. reukaufii may be responsible for the above beneficial interactions. The volatiles produced by the metabolism of M. reukaufii may serve as an honest signal to attract bumblebee pollinators and indirectly promote the female reproductive fitness of C. akebioides, forming a potentially tripartite plant-microbe-pollinator mutualism.


Assuntos
Abelhas , Clematis/fisiologia , Metschnikowia/metabolismo , Néctar de Plantas/fisiologia , Polinização , Animais , Abelhas/fisiologia , Clematis/metabolismo , Clematis/microbiologia , Cromatografia Gasosa-Espectrometria de Massas , Metschnikowia/fisiologia , Polinização/fisiologia , Compostos Orgânicos Voláteis/metabolismo
7.
Protoplasma ; 256(3): 703-720, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30470901

RESUMO

The morpho-anatomical structure of nectaries, osmophores, and elaiophores, and the anatomical and micromorphological features of floral pieces of Cohniella cepula Hoffmans. and Cohniella jonesiana Rchb.f. were comparatively analyzed. In both species, bracteal and sepal nectaries are structured, i.e., they present a secretory epidermis, secretory parenchyma, and vascular bundles. Nectar secretion is released through stomata. The anatomical and micromorphological traits are similar in both nectaries, which can be detected only if the nectar drops are secreted. Considering the location of these nectaries, the secreted nectar would not be a reward to pollinators. Osmophores are located at the base of both callus and laterals lobes, and consist of a layer of secretory epidermis composed of quadrangular cells and papillae. Elaiophores are found on the callus of the labellum and are of the epithelial type. The anatomical features of floral pieces are similar in both species. The anatomical analysis of sepals and petals showed a few differences, which could be of potential taxonomic value. Our results contribute valuable and novel information for the knowledge of these species and the genus, which will be useful in future taxonomic evaluations.


Assuntos
Flores/anatomia & histologia , Orchidaceae/anatomia & histologia , Néctar de Plantas/fisiologia , Flores/citologia , Flores/ultraestrutura , Orchidaceae/citologia , Orchidaceae/ultraestrutura
8.
Bull Entomol Res ; 109(2): 160-168, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29743126

RESUMO

The importance of the right food source for the survival and reproduction of certain insect species is well documented. In the case of biocontrol agents, this is even more important in order to reach a high predation or parasitation performance. The egg parasitoid Telenomus laeviceps (Förster, 1861) (Hymenoptera: Scelionidae) is a promising candidate for mass release as a biological control agent of the cabbage moth Mamestra brassicae (Linnaeus, 1758) (Lepidoptera: Noctuidae). However, adult T. laeviceps need a sugar-rich food source to increase their parasitation performance and produce a good amount of female offspring. Released biocontrol agents were shown to benefit from conservation biocontrol, which includes the provision of selected flowers as nectar resources for beneficial insects. In Switzerland, Centaurea cyanus L. (Asteraceae), Fagopyrum esculentum Moench (Polygonaceae) and Vicia sativa L. (Fabaceae) are successfully implemented in the field to attract and promote natural enemies of different cabbage pests. In this study, we investigated the potential of these selected flowers to attract and promote T. laeviceps under laboratory conditions. In Y-tube olfactometer experiments, we first tested whether the three nectar providing plant species are attractive to T. laeviceps. Furthermore, we assessed their effects on survival and parasitation performance of adult T. laeviceps. We found that flowers of F. esculentum and C. cyanus were attractive in contrast to V. sativa. Also fecundity and the number of female offspring produced were higher for females kept on F. esculentum and C. cyanus than on V. sativa. In contrast, survival was similar on all treatments. Our findings present a further key step towards the implementation of T. laeviceps as a biocontrol agent.


Assuntos
Flores , Interações Hospedeiro-Parasita , Mariposas , Controle Biológico de Vetores , Néctar de Plantas/fisiologia , Vespas/fisiologia , Animais , Centaurea , Fagopyrum , Feminino , Masculino , Olfatometria , Vicia sativa
9.
New Phytol ; 222(2): 1123-1138, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30570752

RESUMO

Floral nectar spurs are widely considered a key innovation promoting diversification in angiosperms by means of pollinator shifts. We investigated the macroevolutionary dynamics of nectar spurs in the tribe Antirrhineae (Plantaginaceae), which contains 29 genera and 300-400 species (70-80% spurred). The effect of nectar spurs on diversification was tested, with special focus on Linaria, the genus with the highest number of species. We generated the most comprehensive phylogeny of Antirrhineae to date and reconstructed the evolution of nectar spurs. Diversification rate heterogeneity was investigated using trait-dependent and trait-independent methods, and accounting for taxonomic uncertainty. The association between changes in spur length and speciation was examined within Linaria using model testing and ancestral state reconstructions. We inferred four independent acquisitions of nectar spurs. Diversification analyses revealed that nectar spurs are loosely associated with increased diversification rates. Detected rate shifts were delayed by 5-15 Myr with respect to the acquisition of the trait. Active evolution of spur length, fitting a speciational model, was inferred in Linaria, which is consistent with a scenario of pollinator shifts driving diversification. Nectar spurs played a role in diversification of the Antirrhineae, but diversification dynamics can only be fully explained by the complex interaction of multiple biotic and abiotic factors.


Assuntos
Evolução Biológica , Flores/anatomia & histologia , Néctar de Plantas/fisiologia , Biodiversidade , Linaria/anatomia & histologia , Modelos Biológicos , Filogenia
10.
Protoplasma ; 255(6): 1811-1825, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29948365

RESUMO

The analysis of flowers collected at different stages of anthesis provides strong evidence to conclude that the shell-shaped hypochile and the knobs of epichile form a nectary. The scent comes from the aromatic constituents of nectar and the epichile tissue and the apices of all tepals (osmophores). The comparison between pollinated and unpollinated flowers revealed that the anthesis of unpollinated flowers lasted up to the 16th day. The nectariferous secretory cells formed single-layered epidermis and several layers of underlying parenchyma built by small, isodiametric cells with thin walls and dense cytoplasm, relatively large nuclei, supplied by collateral vascular bundles. During the floral lifespan, the residues of secreted material were higher on the hypochile cells. The lipoid-carbohydrate material and lipid globules in the cell walls and in the cytoplasm were localised. The abundance of starch grains was observed at the beginning of anthesis and their gradual reduction during the flower lifespan. At the end of anthesis in unpollinated flowers, the lipoid-carbohydrate-phenolic materials have been demonstrated. The phenolic material was the same as in plastoglobuli. The features such as irregular plasmalemma, the secretory vesicles that fuse with it, fully developed dictyosomes, numerous profiles of ER indicate vesicle-mediated process of secretion. The substances could be transported by vesicles to the periplasmic space via granulocrine secretion and then to the external surface. Both micro-channels and slightly developed periplasmic space were visible in the hypochile epidermis. This is the first time for anatomical survey of secretory tissue in pollinated and unpollinated flowers of E. helleborine.


Assuntos
Flores/anatomia & histologia , Orchidaceae/anatomia & histologia , Néctar de Plantas/fisiologia , Flores/citologia , Flores/ultraestrutura , Orchidaceae/citologia , Orchidaceae/ultraestrutura , Epiderme Vegetal/citologia , Epiderme Vegetal/ultraestrutura , Polinização/fisiologia
11.
PLoS One ; 13(6): e0199764, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29949639

RESUMO

Variation in partner species and frequency of interaction between species pairs are potential drivers of the net outcome of generalized mutualisms. In ant-plant mutualisms, the quality of defence provided by ants is related to ant aggressiveness. Hence, we hypothesize that the performance of plants bearing extrafloral nectaries will be higher when they interact more frequently with more aggressive ant species. We estimated ant aggressiveness in the field by observing their behaviour towards soil baits. Afterwards, we observed the frequency with which individuals from these ant species visited plants through an entire reproductive cycle. We measured the production and persistence of plants reproductive structures through this period and the total seed production. Increasing in the interaction frequency with highly aggressive ants reduced the number of floral buds and seeds produced. Increased visitation frequency by less aggressive ants increased the number of floral buds and seeds per branch. The inverse relationship between ant aggressiveness and seed production may be influenced by the costs imposed by different mutualistic partners. Thus, frequent interaction with highly aggressive ants may lead to a higher accumulation of costs through time, resulting in a negative net outcome for the plants. Our results bring new evidence highlighting the importance to incorporate temporal aspects in the study of mutualistic interactions. We suggests that the quality of mutualistic partners must be understood as a function of its per-interaction benefit and their cumulative costs to their partner over time, what puts in check our current classification regarding partner quality in mutualistic systems.


Assuntos
Formigas/fisiologia , Néctar de Plantas/fisiologia , Simbiose , Turnera/fisiologia , Agressão , Animais , Flores/fisiologia , Frutas/fisiologia , Reprodução , Sementes/fisiologia
12.
Am J Bot ; 105(5): 943-949, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29797579

RESUMO

PREMISE OF THE STUDY: Organisms engage in multiple species interactions simultaneously. While pollination studies generally focus on plants and pollinators exclusively, secondary robbing, a behavior that requires other species (primary robbers) to first create access holes in corollas, is common. It has been shown that secondary robbing can reduce plants' female fitness; however, we lack knowledge about its impact on male plant fitness. METHODS: We experimentally simulated primary and secondary robbing in the monocarpic perennial Ipomopsis aggregata (Polemoniaceae), quantifying indirect effects on pollinator-mediated pollen (dye) donation. We also assessed whether continual nectar removal via the floral opening has similar effects on hummingbird-pollinator behavior as continual secondary robbing through robber holes. KEY RESULTS: We found no significant indirect effects of secondary robbing on a component of Ipomopsis male fitness. Although robbing did reduce pollen (dye) donation due to avoidance of robbed plants by pollinating hummingbirds, pollen donation did not differ between the two robbing treatments. The effects of secondary robbing on hummingbird behavior resembled effects of chronic nectar removal by pollinators. Our results indicate that hummingbird pollinators may use a combination of cues, including cues given by the presence or absence of nectar, to make foraging decisions. CONCLUSIONS: Combined with prior research, this study suggests that secondary robbing is less costly to a component of male fitness than to female fitness in Ipomopsis, broadening our knowledge of the overall costs of mutualism exploitation to total plant fitness.


Assuntos
Ericales/fisiologia , Aptidão Genética/fisiologia , Néctar de Plantas/fisiologia , Polinização , Animais , Aves/fisiologia , Ericales/genética , Comportamento Alimentar , Flores/fisiologia , Reprodução
13.
Plant Biol (Stuttg) ; 20 Suppl 1: 224-230, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28960844

RESUMO

Interactions among plant species via pollinators vary from competitive to mutualistic and can influence the probability of stable coexistence of plant species. We aimed to determine the nature of the interaction via flower visitors between Leucospermum conocarpodendron and Mimetes fimbriifolius, two shrubs in the Proteaceae that share many ecological traits and coexist on the Cape Peninsula, South Africa. To assess the extent of pollinator sharing we analysed nectar properties and recorded the pollinator fauna, their behaviour and contribution to seed set. To test for competition via interspecific pollen transfer, we recorded the movement patterns of pollinators and quantified pollen loads. To determine the effect of co-flowering on visitation rates we recorded visits in stands that varied in the density of the two species. We found that the species produce similar rewards and share pollinating Cape Sugarbirds (Promerops cafer). Interspecific pollen transfer is avoided by placing pollen on different parts of the bird. Both species are visited by nectar-thieving Orange-breasted Sunbirds (Anthobaphes violacea). Insects and autonomous self-pollination contributed little to seed set. Pollinator visits increased with conspecific density in both species, and the slope of the increase was steepest in the presence of high densities of the co-occurring plant species. Nectar thief visits also increased with conspecific density in both species, but the slope declined with increasing density of the co-occurring species. Co-occurrence enhanced pollinator visits and alleviated nectar robbing in both plant species, consistent with mutualisms. Mutualism within a trophic level is unusual, but may help to explain the stable coexistence of ecologically similar species.


Assuntos
Aves/fisiologia , Proteaceae/fisiologia , Simbiose , Animais , Clima , Ecossistema , Insetos/fisiologia , Néctar de Plantas/fisiologia , Polinização/fisiologia , África do Sul
14.
Plant Sci ; 262: 148-164, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28716410

RESUMO

Plants attract mutualistic animals by offering a reward of nectar. Specifically, floral nectar (FN) is produced to attract pollinators, whereas extrafloral nectar (EFN) mediates indirect defenses through the attraction of mutualist predatory insects to limit herbivory. Nearly 90% of all plant species, including 75% of domesticated crops, benefit from animal-mediated pollination, which is largely facilitated by FN. Moreover, EFN represents one of the few defense mechanisms for which stable effects on plant health and fitness have been demonstrated in multiple systems, and thus plays a crucial role in the resistance phenotype of plants producing it. In spite of its central role in plant-animal interactions, the molecular events involved in the development of both floral and extrafloral nectaries (the glands that produce nectar), as well as the synthesis and secretion of the nectar itself, have been poorly understood until recently. This review will cover major recent developments in the understanding of (1) nectar chemistry and its role in plant-mutualist interactions, (2) the structure and development of nectaries, (3) nectar production, and (4) its regulation by phytohormones.


Assuntos
Ecossistema , Néctar de Plantas/metabolismo , Néctar de Plantas/fisiologia , Animais , Insetos/fisiologia , Polinização/genética , Polinização/fisiologia
15.
Plant Biol (Stuttg) ; 19(5): 798-805, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28561940

RESUMO

Mexico has one of the highest diversities of barrel cacti species worldwide; however, all are threatened and require conservation policies. Information on their reproductive biology is crucial, but few studies are available. Ferocactus recurvus subsp. recurvus is a barrel cactus endemic to the Tehuacán-Cuicatlán Valley. Our research aimed to characterise its floral and pollination biology. We hypothesised bee pollination, as suggested by its floral morphology and behaviour, and self-incompatibility, like most barrel cacti studied. Three study sites were selected in the semiarid Zapotitlán Valley, Mexico. We examined 190 flowers from 180 plants to determine: morphometry and behaviour of flowers, flower visitors and probable pollinators, and breeding system. Flowers showed diurnal anthesis, lasting 2-5 days, the stigma being receptive on day 2 or 3 after the start of anthesis. Flowers produced scarce/no nectar and main visitors were bees (Apidae), followed by flies (Muscidae), ants (Formicidae), thrips (Thripidae) and hummingbirds (Throchilidae); however, only native bees and occasionally wasps contacted the stigma and anthers. Pollination experiments revealed that this species is self-incompatible and xenogamous. In natural conditions, fruit set was 60% and cross-pollination fruit set was 100%. Percentage seed germination resulting from cross-pollination was higher than in the control treatment. Our results provide ecological information for conservation programmes to ensure a high probability of breeding and seed production in natural populations of F. recurvus.


Assuntos
Cactaceae/fisiologia , Polinização/fisiologia , Reprodução/fisiologia , Animais , Formigas/fisiologia , Abelhas/fisiologia , Aves/fisiologia , Flores/fisiologia , México , Néctar de Plantas/fisiologia , Pólen/fisiologia
16.
New Phytol ; 215(2): 792-802, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28517023

RESUMO

Altered precipitation patterns associated with anthropogenic climate change are expected to have many effects on plants and insect pollinators, but it is unknown if effects on pollination are mediated by changes in water availability. We tested the hypothesis that impacts of climate on plant-pollinator interactions operate through changes in water availability, and specifically that such effects occur through alteration of floral attractants. We manipulated water availability in two naturally occurring Mertensia ciliata (Boraginaceae) populations using water addition, water reduction and control plots and measured effects on vegetative and floral traits, pollinator visitation and seed set. While most floral trait values, including corolla size and nectar, increased linearly with increasing water availability, in this bumblebee-pollinated species, pollinator visitation peaked at intermediate water levels. Visitation also peaked at an intermediate corolla length, while its relationship to corolla width varied across sites. Seed set, however, increased linearly with water. These results demonstrate the potential for changes in water availability to impact plant-pollinator interactions through pollinator responses to differences in floral attractants, and that the effects of water on pollinator visitation can be nonlinear. Plant responses to changes in resource availability may be an important mechanism by which climate change will affect species interactions.


Assuntos
Abelhas , Boraginaceae/fisiologia , Polinização , Sementes/crescimento & desenvolvimento , Animais , Colorado , Secas , Flores/fisiologia , Néctar de Plantas/fisiologia , Solo/química , Água
17.
Plant Biol (Stuttg) ; 19(5): 760-766, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28509436

RESUMO

Studies have indicated that florivory and nectar robbing may reduce reproductive success of host plants. However, whether and how these effects might interact when plants are simultaneously attacked by both florivores and nectar robbers still needs further investigation. We used Iris bulleyana to detect the interactions among florivory, nectar robbing and pollination, and moreover, their effects on plant reproductive success. Field investigations and hand-pollination treatments were conducted on two experimental plots from a natural population, in which Experimental plot was protected from florivores and Control plot was not manipulated. The flower calyx was bitten by sawflies to consume the nectary, and three bumblebee species were pollinators. In addition, the short-tongued pollinator, Bombus friseanus, was the only robber when there was a hole made by a sawfly. The bumblebee had significantly shortened flower handling time when robbing, as compared to legitimate visits. Pollinator visitation and seed production decreased significantly in damaged flowers. However, seed production per flower after supplementary hand-pollination did not differ significantly between damaged and undamaged flowers. Compared to the Experimental plot, bumblebees visited fewer flowers per plant in a foraging bout in the Control plot. The flowers damaged by florivory allowed B. friseanus to shift to a nectar robber. Florivory and nectar robbing collectively decreased plant reproductive success by consuming nectar resources, which may reduce attractiveness to pollinators of the damaged flowers. However, the changes in pollinator behaviour might be beneficial to the plant by reducing the risk of geitonogamous mating.


Assuntos
Iridaceae/fisiologia , Néctar de Plantas/fisiologia , Polinização/fisiologia , Reprodução/fisiologia , Animais , Abelhas/fisiologia
18.
Plant Biol (Stuttg) ; 19(5): 767-774, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28493285

RESUMO

The discrepancy between observed flower visitors and those predicted based on floral phenotype has often cast doubt on the pollination syndrome concept. Here we show that this paradox may be alleviated by gaining better knowledge of the contributions of different flower visitors to pollination and the effects of floral traits that cannot be readily perceived by humans in Adenophora triphylla var. japonica. The blue, bell-shaped and pendant flowers of A. triphylla appear to fit a bee pollination syndrome. In contrast to this expectation, recent studies show that these flowers are frequented by nocturnal moths. We compared the flower visitor fauna, their visitation frequency and their relative contributions to seed set between day and night in two field populations of A. triphylla in Japan. We also determined the floral traits associated with temporal changes in the visitor assemblage, i.e. the timing of anthesis, the timing of changes in the sexual phase and the diel pattern of nectar production. While A. triphylla flowers were visited by both diurnal and nocturnal insects, the results from pollination experiments demonstrate that their primary pollinators are nocturnal settling-moths. Moreover, the flowers opened just after sunset, changed from staminate to pistillate phase in successive evenings and produced nectar only during the night, which all conform to the activity of nocturnal/crepuscular moths. Our study illustrates that the tradition of stereotyping the pollinators of a flower based on its appearance can be misleading and that it should be improved with empirical evidence of pollination performance and sufficient trait matching.


Assuntos
Campanulaceae/fisiologia , Flores/fisiologia , Néctar de Plantas/fisiologia , Polinização/fisiologia , Adaptação Fisiológica , Animais , Abelhas/fisiologia , Mariposas/fisiologia
19.
PLoS One ; 12(5): e0176865, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28467507

RESUMO

Floral nectar contains mainly sugars but also amino acids, organic acids, inorganic ions and secondary compounds to attract pollinators. The genus Nicotiana exhibits great diversity among species in floral morphology, flowering time, nectar compositions, and predominant pollinators. We studied nectar samples of 20 Nicotiana species, composed equally of day- and night-flowering plants and attracting different groups of pollinators (e.g. hummingbirds, moths or bats) to investigate whether sugars, amino acids, organic acids and inorganic ions are influenced by pollinator preferences. Glucose, fructose and sucrose were the only sugars found in the nectar of all examined species. Sugar concentration of the nectar of day-flowering species was 20% higher and amino acid concentration was 2-3-fold higher compared to the nectar of night-flowering species. The sucrose-to-hexose ratio was significantly higher in night-flowering species and the relative share of sucrose based on the total sugar correlated with the flower tube length in the nocturnal species. Flowers of different tobacco species contained varying volumes of nectar which led to about 150-fold higher amounts of total sugar per flower in bat- or sunbird-pollinated species than in bee-pollinated or autogamous species. This difference was even higher for total amino acids per flower (up to 1000-fold). As a consequence, some Nicotiana species invest large amounts of organic nitrogen for certain pollinators. Higher concentrations of inorganic ions, predominantly anions, were found in nectar of night-flowering species. Therefore, higher anion concentrations were also associated with pollinator types active at night. Malate, the main organic acid, was present in all nectar samples but the concentration was not correlated with pollinator type. In conclusion, statistical analyses revealed that pollinator types have a stronger effect on nectar composition than phylogenetic relations. In this context, nectar sugars and amino acids are more strongly correlated with the preferences of predominant pollinators than organic acids and inorganic ions.


Assuntos
Aminoácidos/análise , Carboidratos/análise , Néctar de Plantas/fisiologia , Polinização , Tabaco/metabolismo , Aminoácidos/metabolismo , Animais , Aves , Quirópteros , Ritmo Circadiano , Frutose/análise , Glucose/análise , Malatos/análise , Mariposas , Néctar de Plantas/química , Polinização/fisiologia , Sacarose/análise , Tabaco/fisiologia
20.
Plant Biol (Stuttg) ; 19(5): 775-786, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28504871

RESUMO

Unrelated plants adapted to particular pollinator types tend to exhibit convergent evolution in floral traits. However, inferences about likely pollinators from 'pollination syndromes' can be problematic due to trait overlap among some syndromes and unusual floral architecture in some lineages. An example is the rare South African parasitic plant Mystropetalon thomii (Mystropetalaceae), which has highly unusual brush-like inflorescences that exhibit features of both bird and rodent pollination syndromes. We used camera traps to record flower visitors, quantified floral spectral reflectance and nectar and scent production, experimentally determined self-compatibility and breeding system, and studied pollen dispersal using fluorescent dyes. The dark-red inflorescences are usually monoecious, with female flowers maturing before male flowers, but some inflorescences are purely female (gynoecious). Inflorescences were visited intensively by several rodent species that carried large pollen loads, while visits by birds were extremely rare. Rodents prefer male- over female-phase inflorescences, likely because of the male flowers' higher nectar and scent production. The floral scent contains several compounds known to attract rodents. Despite the obvious pollen transfer by rodents, we found that flowers on both monoecious and gynoecious inflorescences readily set seed in the absence of rodents and even when all flower visitors are excluded. Our findings suggest that seed production occurs at least partially through apomixis and that M. thomii is not ecologically dependent on its rodent pollinators. Our study adds another species and family to the growing list of rodent-pollinated plants, thus contributing to our understanding of the floral traits associated with pollination by non-flying mammals.


Assuntos
Polinização/fisiologia , Roedores/fisiologia , Animais , Aves/fisiologia , Cruzamento , Flores/fisiologia , Néctar de Plantas/fisiologia , Pólen/metabolismo , Pólen/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA