| 1. |
- Tröger, Armin, et al.
(författare)
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Tetranorsesquiterpenoids as attractants of yucca moths to yucca flowers
- 2021
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 47:12, s. 1025-1041
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Tidskriftsartikel (refereegranskat)abstract
- The obligate pollination mutualism between Yucca and yucca moths is a classical example of coevolution. Oviposition and active pollination by female yucca moths occur at night when Yucca flowers are open and strongly scented. Thus, floral volatiles have been suggested as key sensory signals attracting yucca moths to their host plants, but no bioactive compounds have yet been identified. In this study, we showed that both sexes of the pollinator moth Tegeticula yuccasella are attracted to the floral scent of the host Yucca filamentosa. Chemical analysis of the floral headspace from six Yucca species in sections Chaenocarpa and Sarcocarpa revealed a set of novel tetranorsesquiterpenoids putatively derived from (E)-4,8-dimethyl-1,3,7-nonatriene. Their structure elucidation was accomplished by NMR analysis of the crude floral scent sample of Yucca treculeana along with GC/MS analysis and confirmed by total synthesis. Since all these volatiles are included in the floral scent of Y. filamentosa, which has been an important model species for understanding the pollination mutualism, we name these compounds filamentolide, filamentol, filamental, and filamentone. Several of these compounds elicited antennal responses in pollinating (Tegeticula) and non-pollinating (Prodoxus) moth species upon stimulation in electrophysiological recordings. In addition, synthetic (Z)-filamentolide attracted significant numbers of both sexes of two associated Prodoxus species in a field trapping experiment. Highly specialized insect-plant interactions, such as obligate pollination mutualisms, are predicted to be maintained through “private channels” dictated by specific compounds. The identification of novel bioactive tetranorsesquiterpenoids is a first step in testing such a hypothesis in the Yucca-yucca moth interaction.
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| 2. |
- Burdon, Rosalie, 1988-, et al.
(författare)
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Scented nectar and the challenge of measuring honest signals in pollination
- 2020
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Ingår i: Journal of Ecology. - : WILEY. - 0022-0477 .- 1365-2745. ; 108:5, s. 2132-2144
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Tidskriftsartikel (refereegranskat)abstract
- Nectar scents are thought to function as honest signals of reward used by pollinators, but this hypothesis has rarely been tested. UsingPenstemon digitalis, we examined honest signalling of the nectar volatile (S)-(+)-linalool and pollinator responses to linalool in both field and laboratory settings. Because our previous work showed that linalool emission was associated with higher female fitness and that nectar is scented with linalool, we hypothesized that linalool was an honest signal of nectar reward. To assess honesty, we measured linalool-nectar associations including nectar volume, sugar amount, concentration and production rate for inflorescences and flowers in several populations. We also assessed whetherBombus impatiens, the main pollinator ofP. digitalisat our sites, can use linalool as a foraging signal. We supplemented real or artificial flowers in the field and laboratory with varying linalool-nectar combinations to measure pollinator behavioural responses. We found that an inflorescence's linalool emissions could be used to predict nectar rewards inP. digitalis, but this was driven by indirect associations with display size rather than directly advertising more profitable flowers. For flowers within inflorescences there was also no evidence for an association between signal and reward. Field tests of bumblebee behaviour were inconclusive. However, in laboratory assays, bumblebees generally used variation in linalool emissions to choose more profitable flowers, demonstrating they can detect differences in linalool emitted byP. digitalisand associate them with reward profitability. These results suggest experiments that decouple display size, scent and reward are necessary to assess whether (and when) bees prefer higher linalool emissions. Bees preferred nectars with lower linalool concentrations when linalool flavoured the nectar solution, suggesting the potential for conflicting pressures on scent emission in the field. Synthesis. Our results highlight the challenges of assessing function for traits important to fitness and suggest that the perception of floral signalling honesty may depend on whether pollinators use inflorescences or flowers within inflorescences when making foraging decisions. We conclude that future research on honest signalling in flowering plants, as well as its connection to phenotypic selection, should explicitly define honesty, in theoretical and experimental contexts.
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| 3. |
- Eisen, Katherine E., et al.
(författare)
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Among- and within-population variation in morphology, rewards, and scent in a hawkmoth-pollinated plant
- 2022
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Ingår i: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 109:11, s. 1794-1810
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Tidskriftsartikel (refereegranskat)abstract
- Premise: Floral scent is a complex trait that mediates many plant–insect interactions, but our understanding of how floral scent variation evolves, either independently or in concert with other traits, remains limited. Assessing variation in floral scent at multiple levels of biological organization and comparing patterns of variation in scent to variation in other floral traits can contribute to our understanding of how scent variation evolves in nature. Methods: We used a greenhouse common garden experiment to investigate variation in floral scent at three scales—within plants, among plants, and among populations—and to determine whether scent, alone or in combination with morphology and rewards, contributes to population differentiation in Oenothera cespitosa subsp. marginata. Its range spans most of the biomes in the western United States, such that variation in both the abiotic and biotic environment could contribute to trait variation. Results: Multiple analytical approaches demonstrated substantial variation among and within populations in compound-specific and total floral scent measures. Overall, populations were differentiated in morphology and reward traits and in scent. Across populations, coupled patterns of variation in linalool, leucine-derived compounds, and hypanthium length are consistent with a long-tongued moth pollination syndrome. Conclusions: The considerable variation in floral scent detected within populations suggests that, similar to other floral traits, variation in floral scent may have a heritable genetic component. Differences in patterns of population differentiation in floral scent and in morphology and rewards indicate that these traits may be shaped by different selective pressures.
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| 4. |
- Eisen, Katherine E., et al.
(författare)
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An analytical pipeline to support robust research on the ecology, evolution, and function of floral volatiles
- 2022
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Ingår i: Frontiers in Ecology and Evolution. - : Frontiers Media SA. - 2296-701X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Research on floral volatiles has grown substantially in the last 20 years, which has generated insights into their diversity and prevalence. These studies have paved the way for new research that explores the evolutionary origins and ecological consequences of different types of variation in floral scent, including community-level, functional, and environmentally induced variation. However, to address these types of questions, novel approaches are needed that can handle large sample sizes, provide quality control measures, and make volatile research more transparent and accessible, particularly for scientists without prior experience in this field. Drawing upon a literature review and our own experiences, we present a set of best practices for next-generation research in floral scent. We outline methods for data collection (experimental designs, methods for conducting field collections, analytical chemistry, compound identification) and data analysis (statistical analysis, database integration) that will facilitate the generation and interpretation of quality data. For the intermediate step of data processing, we created the R package bouquet, which provides a data analysis pipeline. The package contains functions that enable users to convert chromatographic peak integrations to a filtered data table that can be used in subsequent statistical analyses. This package includes default settings for filtering out non-floral compounds, including background contamination, based on our best-practice guidelines, but functions and workflows can be easily customized as necessary. Next-generation research into the ecology and evolution of floral scent has the potential to generate broadly relevant insights into how complex traits evolve, their genomic architecture, and their consequences for ecological interactions. In order to fulfill this potential, the methodology of floral scent studies needs to become more transparent and reproducible. By outlining best practices throughout the lifecycle of a project, from experimental design to statistical analysis, and providing an R package that standardizes the data processing pipeline, we provide a resource for new and seasoned researchers in this field and in adjacent fields, where high-throughput and multi-dimensional datasets are common.
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