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| 2. |
- Burdon, Rosalie C. F., et al.
(författare)
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Spatiotemporal floral scent variation of Penstemon digitalis
- 2015
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 41:7, s. 641-650
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Tidskriftsartikel (refereegranskat)abstract
- Variability in floral volatile emissions can occur temporally through floral development, during diel cycles, as well as spatially within a flower. These spatiotemporal patterns are hypothesized to provide additional information to floral visitors, but they are rarely measured, and their attendant hypotheses are even more rarely tested. In Penstemon digitalis, a plant whose floral scent has been shown to be under strong phenotypic selection for seed fitness, we investigated spatiotemporal variation in floral scent by using dynamic headspace collection, respectively solid-phase microextraction, and analyzed the volatile samples by combined gas chromatography-mass spectrometry. Total volatile emission was greatest during flowering and peak pollinator activity hours, suggesting its importance in mediating ecological interactions. We also detected tissue and reward-specific compounds, consistent with the hypothesis that complexity in floral scent composition reflects several ecological functions. In particular, we found tissue-specific scents for the stigma, stamens, and staminode (a modified sterile stamen common to all Penstemons). Our findings emphasize the dynamic nature of floral scents and highlight a need for greater understanding of ecological and physiological mechanisms driving spatiotemporal patterns in scent production.
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| 3. |
- Burdon, Rosalie, 1988-
(författare)
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The Ecology of Floral Signals in Penstemon digitalis
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, I combined field observations and lab experiments to explore the ecological significance of floral signals in a North American wildflower, Penstemon digitalis. More specifically, to determine the potential mechanisms driving selection on floral scent, I studied how scent mediates interactions with pollinators and antagonists by (1) observing spatiotemporal variation in scent emission (2), floral volatile ability to suppress microbes (3) the honest advertisement of nectar, and (4) if scent could aid pollinator learning by reinforcing visual signals.Scent sampling of flower development, flower tissues, rewards and inflorescence day/night emission, revealed a complexity in floral scent composition and emission that could reflect several ecological functions. The floral bouquet of P. digitalis was strongest when flowers opened, primarily emitted from flower nectaries and was strongest during the day when pollinators are most active, suggesting a role in plant-pollinator interactions.Because linalool was one of the few floral compounds found in nectar where microbe growth can degrade the pollinator reward, I studied its role in plant-microbe interactions. Bacteria strains isolated from floral and vegetative tissues were exposed to varying concentrations of nectar volatiles: linalool and methyl nicotinate. Linalool inhibited bacteria growth rate from all tissue origins whereas methyl nicotinate had little effect, suggesting that microbes could drive selection on linalool emission strength. To determine the extent that linalool could honestly signal nectar availability, linalool-nectar associations were measured for inflorescences and flowers. Linalool predicted inflorescence nectar availability but not flower, exposing a limit to its honesty. Pollinator Bombus impatiens could use linalool as a foraging signal at varying concentrations, suggesting linalool could be learned and used to choose the most rewarding plants. Measurement and comparison of signal-reward associations for both olfactory and visual signals/cues of P. digitalis displays found display size and linalool honest indicators of nectar. Lab behaviour experiments showed multiple signals correlated with reward could increase bumblebee foraging efficiency and promote learning, providing an explanation for why floral displays are complex and consist of multiple signals. Together my results show that an integrated approach is required to understand the mechanisms driving the evolution of the floral phenotype.
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| 4. |
- Caruso, Christina M., et al.
(författare)
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Do Plants Eavesdrop on Floral Scent Signals?
- 2016
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Ingår i: Trends in Plant Science. - : Elsevier BV. - 1360-1385 .- 1878-4372. ; 21:1, s. 9-15
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Forskningsöversikt (refereegranskat)abstract
- Plants emit a diverse array of volatile organic compounds that can function as cues to other plants. Plants can use volatiles emitted by neighbors to gain information about their environment, and respond by adjusting their phenotype. Less is known about whether the many different volatile signals that plants emit are all equally likely to function as cues to other plants. We review evidence for the function of floral volatile signals and conclude that plants are as likely to perceive and respond to floral volatiles as to other, better-studied volatiles. We propose that eavesdropping on floral volatile cues is particularly likely to be adaptive because plants can respond to these cues by adjusting traits that directly affect pollination and mating.
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| 5. |
- Junker, Robert R., et al.
(författare)
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Covariation and phenotypic integration in chemical communication displays : Biosynthetic constraints and eco-evolutionary implications
- 2018
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 220:3, s. 739-749
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Tidskriftsartikel (refereegranskat)abstract
- Chemical communication is ubiquitous. The identification of conserved structural elements in visual and acoustic communication is well established, but comparable information on chemical communication displays (CCDs) is lacking. We assessed the phenotypic integration of CCDs in a meta-analysis to characterize patterns of covariation in CCDs and identified functional or biosynthetically constrained modules. Poorly integrated plant CCDs (i.e. low covariation between scent compounds) support the notion that plants often utilize one or few key compounds to repel antagonists or to attract pollinators and enemies of herbivores. Animal CCDs (mostly insect pheromones) were usually more integrated than those of plants (i.e. stronger covariation), suggesting that animals communicate via fixed proportions among compounds. Both plant and animal CCDs were composed of modules, which are groups of strongly covarying compounds. Biosynthetic similarity of compounds revealed biosynthetic constraints in the covariation patterns of plant CCDs. We provide a novel perspective on chemical communication and a basis for future investigations on structural properties of CCDs. This will facilitate identifying modules and biosynthetic constraints that may affect the outcome of selection and thus provide a predictive framework for evolutionary trajectories of CCDs in plants and animals.
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| 6. |
- Junker, Robert R., et al.
(författare)
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Working Towards a Holistic View on Flower Traits-How Floral Scents Mediate Plant-Animal Interactions in Concert with Other Floral Characters
- 2015
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Ingår i: Journal of the Indian Institute of Science. - 0970-4140. ; 95:1, s. 43-67
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Tidskriftsartikel (refereegranskat)abstract
- Flowers are complex structures, synchronously displaying both olfactory and visual signals/cues in the context of a particular floral morphology, that also vary in resource quantity and quality. Despite or possibly because of this complexity, many studies focus on a single or few traits rather than studying floral phenotypes in a more integrated fashion. However, each of these distinct trait classes (signals/cues, morphology and resources) mediates interactions with floral visitors, demanding a more holistic view of flowers. In our review, we integrate floral scents into the broader context of the whole-flower phenotype. We discuss the functions of scent bouquets, colouration, morphology and rewards in flower visitor interactions from an ecological and evolutionary perspective in isolation and taken together. Studies demonstrate that floral scent bouquets can act additively or synergistically with other modalities, and that their effects on flower visitors are context-dependent. We also present field study results showing that reward levels modulate dose-dependent responses to volatiles by honeybees. To motivate studies examining complex floral phenotypes, we outline statistical approaches suited to deal with the complex multivariate datasets generated by these studies. We conclude with a discussion on why flowers display multimodal traits and suggest future research efforts. Our aim is to foster a fresh view on integrated floral phenotypes and stimulate studies exploring the combined effects of olfactory, visual, morphological and nutritional traits on flower animal interactions.
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| 7. |
- Moritz, Kim, et al.
(författare)
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Female Salix viminalis are more severely infected by Melampsora spp. but neither sex experiences associational effects
- 2016
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 6:4, s. 1154-1162
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Tidskriftsartikel (refereegranskat)abstract
- Associational effects of plant genotype or species on plant biotic interactions are common, not least for disease spread, but associational effects of plant sex on interactions have largely been ignored. Sex in dioecious plants can affect biotic interactions with herbivores and pollinators; however, its effects on plant-pathogen interactions are understudied and associational effects are unknown. In a replicated field experiment, we assessed Melampsora spp. leaf rust infection in monosexual and mixed sex plots of dioecious Salix viminalis L. to determine whether plant sex has either direct or associational effects on infection severity. We found no differences in Melampsora spp. infection severity among sexual monocultures and mixtures in our field experiment. However, female plants were overall more severely infected. In addition, we surveyed previous studies of infection in S.viminalis clones and reevaluated the studies after we assigned sex to the clones. We found that females were generally more severely infected, as in our field study. Similarly, in a survey of studies on sex-biased infection in dioecious plants, we found more female-biased infections in plant-pathogen pairs. We conclude that there was no evidence for associational plant sex effects of neighboring conspecifics for either females or males on infection severity. Instead, plant sex effects on infection act at an individual plant level. Our findings also suggest that female plants may in general be more severely affected by fungal pathogens than males.
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| 8. |
- Moritz, Kim, et al.
(författare)
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Plant sex effects on insect herbivores and biological control in a Short Rotation Coppice willow
- 2017
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Ingår i: Biological control (Print). - : Elsevier BV. - 1049-9644 .- 1090-2112. ; 115, s. 30-36
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Tidskriftsartikel (refereegranskat)abstract
- In the wild, plant sex can affect plant-herbivore interactions and higher trophic levels, including natural enemies of the herbivores. However, the possibility of manipulating plant sex to improve biological control and reduce herbivory in domesticated dioecious crops remains unexplored. The dioecious bioenergy crop, Salix viminalis, is often planted in monoclonal, and thus monosexual, fields. We investigated whether using plant clones of either sex, or mixing plants of both sexes, reduced the performance and abundance of the herbivorous pest insect Phratora vulgatissima and its main natural enemy, Anthocoris nemorum, and whether predation was affected. The herbivore laid more eggs, and the predator survived longer, on female plants in the lab. However, these effects did not translate into differences in predation rates in laboratory experiments or differential insect abundances on plants of either sex or plantation sex composition in the field. Plant genotype did have a significant effect on insect abundances, but this was due to plant traits other than sex. The results indicate that manipulating plant sex will not lead to improved biological control or reduced insect herbivory in S. viminalis energy forestry, but suggest that a focus on plant genotypic differences offers promise for improving management practices.
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| 9. |
- Moritz, Kim, et al.
(författare)
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Roe deer prefer mixed-sex willow stands over monosexual stands but do not discriminate between male and female plants
- 2018
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Ingår i: Environmental and Experimental Botany. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0098-8472 .- 1873-7307. ; 146, s. 62-67
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Tidskriftsartikel (refereegranskat)abstract
- Male and female plants of dioecious species often experience differential herbivory, possibly due to differences in defences such as secondary metabolite composition or nutritional quality. These plant sex effects on herbivory have been extensively studied for plant individuals, but not for stands/populations. For mobile herbivores, such as deer, stands may be a more relevant scale to study than individual plants. We predicted that male Salts viminalis plants should be subject to more extensive roe deer (Capreolus capreolus) browsing than female plants due to weaker defence in male plants. Furthermore, we expected that mixed-sex stands should experience more damage than monosexual stands due to positive effects of diet mixing on browsing by generalists. We tested for differences in roe deer browsing in plots that were either monosexual male or female, or a mix of male and female plants in a replicated field experiment. Roe deer browsing was estimated after one growth season with heavy herbivory. We also measured plant secondary metabolite concentrations and nitrogen content in leaves from all experimental clones to test the assumption that the sexes differed in defence or nutrients. Mixed-sex plots were more extensively browsed than monosexual plots. However, there was no difference in browsing between male and female plant individuals within mixed-sex plots or between monosexual plots. Plant secondary metabolite profiles differed between male and female plants, while nitrogen content did not. Our findings suggest that the diversified plant secondary metabolite contents of mixed-sex plots may have led to more extensive herbivory. Higher browsing of plant sex mixes may impact both natural and commercial S. viminalis stands with different sex ratios.
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| 10. |
- Muola, Anne, et al.
(författare)
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Direct and Pollinator-Mediated Effects of Herbivory on Strawberry and the Potential for Improved Resistance
- 2017
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Ingår i: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The global decline in pollinators has partly been blamed on pesticides, leading some to propose pesticide-free farming as an option to improve pollination. However, herbivores are likely to be more prevalent in pesticide-free environments, requiring knowledge of their effects on pollinators, and alternative crop protection strategies to mitigate any potential pollination reduction. Strawberry leaf beetles (SLB) Galerucella spp. are important strawberry pests in Northern Europe and Russia. Given that SLB attack both leaf and flower tissue, we hypothesized pollinators would discriminate against SLB-damaged strawberry plants (Fragaria vesca, cultivar 'Rugen'), leading to lower pollination success and yield. In addition we screened the most common commercial cultivar 'Rugen' and wild Swedish F. vesca genotypes for SLB resistance to assess the potential for inverse breeding to restore high SLB resistance in cultivated strawberry. Behavioral observations in a controlled experiment revealed that the local pollinator fauna avoided strawberry flowers with SLB-damaged petals. Low pollination, in turn, resulted in smaller more deformed fruits. Furthermore, SLB-damaged flowers produced smaller fruits even when they were hand pollinated, showing herbivore damage also had direct effects on yield, independent of indirect effects on pollination. We found variable resistance in wild woodland strawberry to SLB and more resistant plant genotypes than the cultivar 'Rugen' were identified. Efficient integrated pest management strategies should be employed to mitigate both direct and indirect effects of herbivory for cultivated strawberry, including high intrinsic plant resistance.
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