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Aksamit IC, Dorigão-Guimarães F, Gronenberg W, Godfrey RK. Brain size scaling through development in the whitelined sphinx moth (Hyles lineata) shows mass and cell number comparable to flies, bees, and wasps. ARTHROPOD STRUCTURE & DEVELOPMENT 2024; 78:101329. [PMID: 38171085 DOI: 10.1016/j.asd.2023.101329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 12/13/2023] [Accepted: 12/13/2023] [Indexed: 01/05/2024]
Abstract
Factors regulating larval growth and determinants of adult body size are described for several holometabolous insects, but less is known about brain size scaling through development. Here we use the isotropic fractionation ("brain soup") method to estimate the number of brain cells and cell density for the whitelined sphinx moth (Lepidoptera: Hyles lineata) from the first instar through the adult stage. We measure mass and brain cell number and find that, during the larval stages, body mass shows an exponential relationship with head width, while the total number of brain cells increases asymptotically. Larval brain cell number increases by a factor of ten from nearly 8000 in the first instar to over 80,000 in the fifth instar. Brain cell number increases by another factor of 10 during metamorphosis, with the adult brain containing more than 900,000 cells. This is similar to increases during development in the vinegar fly (Drosophila melanogaster) and the black soldier fly (Hermetia illucens). The adult brain falls slightly below the brain-to-body allometry for wasps and bees but is comparable in the number of cells per unit brain mass, indicating a general conservation of brain cell density across these divergent lineages.
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Affiliation(s)
- Isabel C Aksamit
- Department of Neuroscience, University of Arizona, Tucson, AZ, USA
| | - Felipe Dorigão-Guimarães
- Biodiversity Graduate Program, São Paulo State University (UNESP), Institute of Biosciences, Humanities and Exact Sciences (IBILCE), São José do Rio Preto, SP, Brazil
| | | | - R Keating Godfrey
- Entomology and Nematology Department, University of Florida, Gainesville, FL, USA.
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Dötterl S, Gershenzon J. Chemistry, biosynthesis and biology of floral volatiles: roles in pollination and other functions. Nat Prod Rep 2023; 40:1901-1937. [PMID: 37661854 DOI: 10.1039/d3np00024a] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Covering: 2010 to 2023Floral volatiles are a chemically diverse group of plant metabolites that serve multiple functions. Their composition is shaped by environmental, ecological and evolutionary factors. This review will summarize recent advances in floral scent research from chemical, molecular and ecological perspectives. It will focus on the major chemical classes of floral volatiles, on notable new structures, and on recent discoveries regarding the biosynthesis and the regulation of volatile emission. Special attention will be devoted to the various functions of floral volatiles, not only as attractants for different types of pollinators, but also as defenses of flowers against enemies. We will also summarize recent findings on how floral volatiles are affected by abiotic stressors, such as increased temperatures and drought, and by other organisms, such as herbivores and flower-dwelling microbes. Finally, this review will indicate current research gaps, such as the very limited knowledge of the isomeric pattern of chiral compounds and its importance in interspecific interactions.
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Affiliation(s)
- Stefan Dötterl
- Department of Environment & Biodiversity, Paris Lodron University Salzburg, Hellbrunnerstr 34, 5020 Salzburg, Austria.
| | - Jonathan Gershenzon
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745 Jena, Germany.
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Floral scent divergence across an elevational hybrid zone with varying pollinators. Oecologia 2023; 201:45-57. [PMID: 36374316 DOI: 10.1007/s00442-022-05289-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022]
Abstract
Divergence in floral traits attractive to different pollinators can promote reproductive isolation in related species. When isolation is incomplete, hybridization may occur, which offers the opportunity to explore mechanisms underlying reproductive isolation. Recent work suggests that divergence in floral scent may frequently contribute to reproductive barriers, although such divergence has seldom been examined in species with generalized pollination. Here, we used two closely related Penstemon species, P. newberryi and P. davidsonii, and their natural hybrids from an elevational gradient with pollinator communities that are predicted to vary in their reliance on floral scent (i.e., primarily hummingbirds at low elevation vs. bees at high elevation). The species vary in a suite of floral traits, but scent is uncharacterized. To address whether scent varies along elevation and potentially contributes to reproductive isolation, we genetically characterized individuals collected at field and identified whether they were parental species or hybrids. We then characterized scent amount and composition. Although the parental species had similar total emissions, some scent characteristics (i.e., scent composition, aromatic emission) diverged between them and may contribute to their isolation. However, the species emitted similar compound sets which could explain hybridization in the contact area. Hybrids were similar to the parents for most scent traits, suggesting that their floral scent would not provide a strong barrier to backcrossing. Our study suggests floral scent may be a trait contributing to species boundaries even in plants with generalized pollination, and reinforces the idea that evolutionary pollinator transitions may involve changes in multiple floral traits.
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Eisen KE, Ma R, Raguso RA. Among- and within-population variation in morphology, rewards, and scent in a hawkmoth-pollinated plant. AMERICAN JOURNAL OF BOTANY 2022; 109:1794-1810. [PMID: 35762273 DOI: 10.1002/ajb2.16030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
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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Affiliation(s)
- Katherine E Eisen
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA
- Department of Biology, Lund University, Lund, Sweden
| | - Rong Ma
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA
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Campbell DR, Raguso RA, Midzik M, Bischoff M, Broadhead GT. Genetic and spatial variation in vegetative and floral traits across a hybrid zone. AMERICAN JOURNAL OF BOTANY 2022; 109:1780-1793. [PMID: 36193908 PMCID: PMC9828138 DOI: 10.1002/ajb2.16067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 06/14/2022] [Accepted: 06/15/2022] [Indexed: 06/16/2023]
Abstract
PREMISE Genetic variation influences the potential for evolution to rescue populations from impacts of environmental change. Most studies of genetic variation in fitness-related traits focus on either vegetative or floral traits, with few on floral scent. How vegetative and floral traits compare in potential for adaptive evolution is poorly understood. METHODS We measured variation across source populations, planting sites, and genetic families for vegetative and floral traits in a hybrid zone. Seeds from families of Ipomopsis aggregata, I. tenuituba, and F1 and F2 hybrids of the two species were planted into three common gardens. Measured traits included specific leaf area (SLA), trichomes, water-use efficiency (WUE), floral morphology, petal color, nectar, and floral volatiles. RESULTS Vegetative traits SLA and WUE varied greatly among planting sites, while showing weak or no genetic variation among source populations. Specific leaf area and trichomes responded plastically to snowmelt date, and SLA exhibited within-population genetic variation. All aspects of floral morphology varied genetically among source populations, and corolla length, corolla width, and sepal width varied genetically within populations. Heritability was not detected for volatiles due to high environmental variation, although one terpene had high evolvability, and high emission of two terpenes, a class of compounds emitted more strongly from the calyx than the corolla, correlated genetically with sepal width. Environmental variation across sites was weak for floral morphology and stronger for volatiles and vegetative traits. The inheritance of three of four volatiles departed from additive. CONCLUSIONS Results indicate stronger genetic potential for evolutionary responses to selection in floral morphology compared with scent and vegetative traits and suggest potentially adaptive plasticity in some vegetative traits.
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Affiliation(s)
- Diane R. Campbell
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
- Rocky Mountain Biological LaboratoryCrested ButteCO81224USA
| | - Robert A. Raguso
- Department of Neurobiology and BehaviorCornell UniversityIthacaNY14853USA
| | - Maya Midzik
- Rocky Mountain Biological LaboratoryCrested ButteCO81224USA
| | - Mascha Bischoff
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCA92697USA
- Rocky Mountain Biological LaboratoryCrested ButteCO81224USA
- Department of Neurobiology and BehaviorCornell UniversityIthacaNY14853USA
- Environmental Research Institute, North Highland CollegeCastle StreetThursoKW14 7JDUK
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Eisen KE, Powers JM, Raguso RA, Campbell DR. An analytical pipeline to support robust research on the ecology, evolution, and function of floral volatiles. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1006416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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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Skogen KA, Jogesh T, Hilpman ET, Todd SL, Raguso RA. Extensive population-level sampling reveals clinal variation in (R)-(-)-linalool produced by the flowers of an endemic evening primrose, Oenothera harringtonii. PHYTOCHEMISTRY 2022; 200:113185. [PMID: 35436476 DOI: 10.1016/j.phytochem.2022.113185] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 03/31/2022] [Accepted: 04/01/2022] [Indexed: 06/14/2023]
Abstract
The study of floral trait diversity has a long history due to its role in angiosperm diversification. While many studies have focused on visual traits including morphology and color, few have included floral scent despite its importance in pollination. Of the studies that have included floral scent, sampling has been limited and rarely explores variation at the population level. We studied geographic variation in the flowers of Oenothera harringtonii, a rare plant endemic to a vulnerable shortgrass prairie habitat, whose population structure and conservation status are well studied. The self-incompatible flowers of O. harringtonii open at dusk, produce nectar and a strong fragrance, and are pollinated by hawkmoths. We collected floral trait (morphology, scent chemistry and emission rates) data from 650 individuals from 19 wild populations to survey floral variation across the entire range of this species. Similarly, we collected floral data from 49 individuals grown in a greenhouse common garden, to assess whether variation observed in the field is consistent when environment factors (temperature, watering regime, soil) are standardized. We identified 35 floral volatiles representing 5 biosynthetic classes. Population differentiation was stronger for floral scent chemistry than floral morphology. (R)-(-)-linalool was the most important floral trait differentiating populations, exhibiting clinal variation across the distribution of O. harringtonii without any correlated shifts in floral morphology. Populations in the north and west produced (R)-(-)-linalool consistently, those in the east and south largely lacked it, and populations at the center of the distribution were polymorphic. Floral scent emissions in wild populations varied across four years but chemical composition was largely consistent over time. Similarly, volatile emission rates and chemical composition in greenhouse-grown plants were consistent with those of wild populations of origin. Our data set, which represents the most extensive population-level survey of floral scent to date, indicates that such sampling may be needed to capture potentially adaptive geographic variation in wild populations.
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Affiliation(s)
- Krissa A Skogen
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60035, USA.
| | - Tania Jogesh
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60035, USA
| | - Evan T Hilpman
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60035, USA; School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| | - Sadie L Todd
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60035, USA; Iowa Department of Agriculture and Land Stewardship, Ankeny, IA, 50023, USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA
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Albor C, Ashman T, Stanley A, Martel C, Arceo‐Gómez G. Flower color and flowering phenology mediate plant‐pollinator interaction assembly in a diverse co‐flowering community. Funct Ecol 2022. [DOI: 10.1111/1365-2435.14142] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Cristopher Albor
- Department of Biological Sciences University of Calgary Calgary Alberta Canada
| | - Tia‐Lynn Ashman
- Department of Biological Sciences University of Pittsburgh Pittsburgh Pennsylvania USA
| | - Amber Stanley
- Department of Biological Sciences University of Pittsburgh Pittsburgh Pennsylvania USA
- Department of Biological Sciences East Tennessee State University Johnson City Tennessee USA
| | - Carlos Martel
- Department of Biological Sciences East Tennessee State University Johnson City Tennessee USA
- Current address: Royal Botanical Gardens at Kew London United Kingdom
| | - Gerardo Arceo‐Gómez
- Department of Biological Sciences East Tennessee State University Johnson City Tennessee USA
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Balbuena MS, Broadhead GT, Dahake A, Barnett E, Vergara M, Skogen KA, Jogesh T, Raguso RA. Mutualism has its limits: consequences of asymmetric interactions between a well-defended plant and its herbivorous pollinator. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210166. [PMID: 35491593 DOI: 10.1098/rstb.2021.0166] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Concern for pollinator health often focuses on social bees and their agricultural importance at the expense of other pollinators and their ecosystem services. When pollinating herbivores use the same plants as nectar sources and larval hosts, ecological conflicts emerge for both parties, as the pollinator's services are mitigated by herbivory and its larvae are harmed by plant defences. We tracked individual-level metrics of pollinator health-growth, survivorship, fecundity-across the life cycle of a pollinating herbivore, the common hawkmoth, Hyles lineata, interacting with a rare plant, Oenothera harringtonii, that is polymorphic for the common floral volatile (R)-(-)-linalool. Linalool had no impact on floral attraction, but its experimental addition suppressed oviposition on plants lacking linalool. Plants showed robust resistance against herbivory from leaf-disc to whole-plant scales, through poor larval growth and survivorship. Higher larval performance on other Oenothera species indicates that constitutive herbivore resistance by O. harringtonii is not a genus-wide trait. Leaf volatiles differed among populations of O. harringtonii but were not induced by larval herbivory. Similarly, elagitannins and other phenolics varied among plant tissues but were not herbivore-induced. Our findings highlight asymmetric plant-pollinator interactions and the importance of third parties, including alternative larval host plants, in maintaining pollinator health. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.
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Affiliation(s)
- Maria Sol Balbuena
- Department of Neurobiology and Behaviour, Cornell University, Ithaca, NY 14853, USA.,Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET, Universidad de Buenos Aires, C1428EHA, Argentina
| | - Geoffrey T Broadhead
- Department of Neurobiology and Behaviour, Cornell University, Ithaca, NY 14853, USA
| | - Ajinkya Dahake
- Department of Neurobiology and Behaviour, Cornell University, Ithaca, NY 14853, USA
| | - Emily Barnett
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA
| | - Melissa Vergara
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA
| | - Krissa A Skogen
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL 60035, USA
| | - Tania Jogesh
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA.,Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL 60035, USA
| | - Robert A Raguso
- Department of Neurobiology and Behaviour, Cornell University, Ithaca, NY 14853, USA
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Campbell DR, Bischoff M, Raguso RA, Briggs HM, Sosenski P. Selection of Floral Traits by Pollinators and Seed Predators during Sequential Life History Stages. Am Nat 2022; 199:808-823. [DOI: 10.1086/716740] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Diane R. Campbell
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado 81224
| | - Mascha Bischoff
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado 81224
- Environmental Research Institute, North Highland College, Castle Street, Thurso KW14 7JD, United Kingdom
| | - Robert A. Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853
| | - Heather M. Briggs
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado 81224
| | - Paula Sosenski
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado 81224
- Consejo Nacional de Ciencia y Tecnología (CONACYT)–Departamento de Ecología Tropical, Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico
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Guo M, Ren X, Liu Y, Wang G. An Odorant Receptor from the Proboscis of the Cotton Bollworm Helicoverpa armigera (Lepidoptera: Noctuidae) Narrowly Tuned to Indole. INSECTS 2022; 13:insects13040385. [PMID: 35447827 PMCID: PMC9033110 DOI: 10.3390/insects13040385] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/09/2022] [Accepted: 04/11/2022] [Indexed: 01/18/2023]
Abstract
Simple Summary Odorant receptors (ORs) are at the core of the high-efficiency and sensitive olfactory system in insects. The expression and specific function of ORs largely contribute to the habits and speciation of one species. Although being predominantly expressed in the antennae, ORs in non-olfactory organs are suggested to have particular roles in promoting the reproduction or host fitness of insects. Our previous work has identified four ORs in the mouthpart organs of Helicoverpa armigera. Here, we amplified the full-length sequences of HarmORs from the proboscis. Further functional characterization suggested that HarmOR30 narrowly tuned to indole, the vital nitrogen-containing compounds that mediate tritrophic interactions. Our study deepens the insight into the olfactory perception of H. armigera, and explored a candidate functional receptor target for studying the interaction between insects and their plant hosts. Abstract Helicoverpa armigera is a serious agricultural pest with polyphagous diets, widespread distribution, and causing severe damage. Among sixty-five candidate ORs in H. armigera, the co-receptor HarmOrco and three specific ORs with partial sequences were identified to be expressed in the proboscis by our previous work, whereas their exact function is not known yet. In this study, we first confirmed the expression of these ORs in the proboscis by full-length cloning, which obtained the complete coding region of HarmOrco, OR24, and OR30. We then performed functional identification of HarmOR24 and OR30 by co-expressing them respectively with HarmOrco in Xenopus oocytes eukaryotic expression system combined with two-electrode voltage-clamp physiology. By testing the response of HarmOR24/OR30-expressing oocytes against eighty structural-divergent compounds, respectively, HarmOR30 was characterized to narrowly tune to indole and showed a specific tuning spectrum compared to its ortholog in Spodoptera littoralis. As indole is a distinctive herbivore-induced plant volatile and floral scent component, HarmOR30 might play roles in foraging and mediating the interactions between H. armigera with its surrounding environment.
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Affiliation(s)
- Mengbo Guo
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China;
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (X.R.); (Y.L.)
| | - Xueting Ren
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (X.R.); (Y.L.)
| | - Yang Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (X.R.); (Y.L.)
| | - Guirong Wang
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China;
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (X.R.); (Y.L.)
- Correspondence: ; Tel.: +86-010-628-16947
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12
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Bechen LL, Johnson MG, Broadhead GT, Levin RA, Overson RP, Jogesh T, Fant JB, Raguso RA, Skogen KA, Wickett NJ. Differential gene expression associated with a floral scent polymorphism in the evening primrose Oenothera harringtonii (Onagraceae). BMC Genomics 2022; 23:124. [PMID: 35151274 PMCID: PMC8840323 DOI: 10.1186/s12864-022-08370-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Accepted: 12/30/2021] [Indexed: 12/13/2022] Open
Abstract
Background Plant volatiles play an important role in both plant-pollinator and plant-herbivore interactions. Intraspecific polymorphisms in volatile production are ubiquitous, but studies that explore underlying differential gene expression are rare. Oenothera harringtonii populations are polymorphic in floral emission of the monoterpene (R)-(−)-linalool; some plants emit (R)-(−)-linalool (linalool+ plants) while others do not (linalool- plants). However, the genes associated with differential production of this floral volatile in Oenothera are unknown. We used RNA-Seq to broadly characterize differential gene expression involved in (R)-(−)-linalool biosynthesis. To identify genes that may be associated with the polymorphism for this trait, we used RNA-Seq to compare gene expression in six different Oenothera harringtonii tissues from each of three linalool+ and linalool- plants. Results Three clusters of differentially expressed genes were enriched for terpene synthase activity: two were characterized by tissue-specific upregulation and one by upregulation only in plants with flowers that produce (R)-(−)-linalool. A molecular phylogeny of all terpene synthases identified two putative (R)-(−)-linalool synthase transcripts in Oenothera harringtonii, a single allele of which is found exclusively in linalool+ plants. Conclusions By using a naturally occurring polymorphism and comparing different tissues, we were able to identify candidate genes putatively involved in the biosynthesis of (R)-(−)-linalool. Expression of these genes in linalool- plants, while low, suggests a regulatory polymorphism, rather than a population-specific loss-of-function allele. Additional terpene biosynthesis-related genes that are up-regulated in plants that emit (R)-(−)-linalool may be associated with herbivore defense, suggesting a potential economy of scale between plant reproduction and defense. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-022-08370-6.
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Trunschke J, Lunau K, Pyke GH, Ren ZX, Wang H. Flower Color Evolution and the Evidence of Pollinator-Mediated Selection. FRONTIERS IN PLANT SCIENCE 2021; 12:617851. [PMID: 34381464 PMCID: PMC8350172 DOI: 10.3389/fpls.2021.617851] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 05/14/2021] [Indexed: 06/01/2023]
Abstract
The evolution of floral traits in animal-pollinated plants involves the interaction between flowers as signal senders and pollinators as signal receivers. Flower colors are very diverse, effect pollinator attraction and flower foraging behavior, and are hypothesized to be shaped through pollinator-mediated selection. However, most of our current understanding of flower color evolution arises from variation between discrete color morphs and completed color shifts accompanying pollinator shifts, while evidence for pollinator-mediated selection on continuous variation in flower colors within populations is still scarce. In this review, we summarize experiments quantifying selection on continuous flower color variation in natural plant populations in the context of pollinator interactions. We found that evidence for significant pollinator-mediated selection is surprisingly limited among existing studies. We propose several possible explanations related to the complexity in the interaction between the colors of flowers and the sensory and cognitive abilities of pollinators as well as pollinator behavioral responses, on the one hand, and the distribution of variation in color phenotypes and fitness, on the other hand. We emphasize currently persisting weaknesses in experimental procedures, and provide some suggestions for how to improve methodology. In conclusion, we encourage future research to bring together plant and animal scientists to jointly forward our understanding of the mechanisms and circumstances of pollinator-mediated selection on flower color.
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Affiliation(s)
- Judith Trunschke
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Klaus Lunau
- Institute of Sensory Ecology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Graham H. Pyke
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Department of Biological Sciences, Macquarie University, Ryde, NSW, Australia
| | - Zong-Xin Ren
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Hong Wang
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
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14
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Wenzell KE, McDonnell AJ, Wickett NJ, Fant JB, Skogen KA. Incomplete reproductive isolation and low genetic differentiation despite floral divergence across varying geographic scales in Castilleja. AMERICAN JOURNAL OF BOTANY 2021; 108:1270-1288. [PMID: 34289081 DOI: 10.1002/ajb2.1700] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/18/2021] [Indexed: 06/13/2023]
Abstract
PREMISE Divergence depends on the strength of selection and frequency of gene flow between taxa, while reproductive isolation relies on mating barriers and geographic distance. Less is known about how these processes interact at early stages of speciation. Here, we compared population-level differentiation in floral phenotype and genetic sequence variation among recently diverged Castilleja to explore patterns of diversification under different scenarios of reproductive isolation. METHODS Using target enrichment enabled by the Angiosperms353 probe set, we assessed genetic distance among 50 populations of four Castilleja species. We investigated whether patterns of genetic divergence are explained by floral trait variation or geographic distance in two focal groups: the widespread C. sessiliflora and the more restricted C. purpurea species complex. RESULTS We document that C. sessiliflora and the C. purpurea complex are characterized by high diversity in floral color across varying geographic scales. Despite phenotypic divergence, groups were not well supported in phylogenetic analyses, and little genetic differentiation was found across targeted Angiosperms353 loci. Nonetheless, a principal coordinate analysis of single nucleotide polymorphisms revealed differentiation within C. sessiliflora across floral morphs and geography and less differentiation among species of the C. purpurea complex. CONCLUSIONS Patterns of genetic distance in C. sessiliflora suggest species cohesion maintained over long distances despite variation in floral traits. In the C. purpurea complex, divergence in floral color across narrow geographic clines may be driven by recent selection on floral color. These contrasting patterns of floral and genetic differentiation reveal that divergence can arise via multiple eco-evolutionary paths.
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Affiliation(s)
- Katherine E Wenzell
- Program in Plant Biology and Conservation, Northwestern University, O.T. Hogan Hall, Room 6-140B, 2205 Tech Drive, Evanston, IL, 60208, USA
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60022, USA
- John Innes Centre, Norwich Research Park, Colney Lane, Norwich, NR4 7UH, UK
| | - Angela J McDonnell
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60022, USA
| | - Norman J Wickett
- Program in Plant Biology and Conservation, Northwestern University, O.T. Hogan Hall, Room 6-140B, 2205 Tech Drive, Evanston, IL, 60208, USA
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60022, USA
| | - Jeremie B Fant
- Program in Plant Biology and Conservation, Northwestern University, O.T. Hogan Hall, Room 6-140B, 2205 Tech Drive, Evanston, IL, 60208, USA
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60022, USA
| | - Krissa A Skogen
- Program in Plant Biology and Conservation, Northwestern University, O.T. Hogan Hall, Room 6-140B, 2205 Tech Drive, Evanston, IL, 60208, USA
- Negaunee Institute for Plant Conservation Science and Action, Chicago Botanic Garden, Glencoe, IL, 60022, USA
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15
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Christie K, Doan JP, Mcbride WC, Strauss SY. Asymmetrical reproductive barriers in sympatric jewelflowers: are floral isolation, genetic incompatibilities and floral trait displacement connected? Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Floral visitors influence reproductive interactions among sympatric plant species, either by facilitating assortative mating and contributing to reproductive isolation, or by promoting heterospecific pollen transfer, potentially leading to reproductive interference or hybridization. We assessed preference and constancy of floral visitors on two co-occurring jewelflowers [Streptanthus breweri and Streptanthus hesperidis (Brassicaceae)] using field arrays, and quantified two floral rewards potentially important to foraging choice – pollen production and nectar sugar concentration – in a greenhouse common garden. Floral visitors made an abundance of conspecific transitions between S. breweri individuals, which thus experienced minimal opportunities for heterospecific pollen transfer from S. hesperidis. In contrast, behavioural isolation for S. hesperidis was essentially absent due to pollinator inconstancy. This pattern emerged across multiple biotic environments and was unrelated to local density dependence. S. breweri populations that were sympatric with S. hesperidis had higher nectar sugar concentrations than their sympatric congeners, as well as allopatric conspecifics. Previous work shows that S. breweri suffers a greater cost to hybridization than S. hesperidis, and here we find that it also shows asymmetrical floral isolation and floral trait displacement in sympatry. These findings suggest that trait divergence may reduce negative reproductive interactions between sympatric but genetically incompatible relatives.
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Affiliation(s)
- Kyle Christie
- Department of Evolution and Ecology, University of California Davis, One Shields Avenue, Davis, CA, USA
- Center for Population Biology, University of California Davis, One Shields Avenue, Davis, CA, USA
| | - Jonathan P Doan
- Department of Evolution and Ecology, University of California Davis, One Shields Avenue, Davis, CA, USA
| | - Wendy C Mcbride
- Deaver Herbarium, Northern Arizona University, Flagstaff, AZ, USA
| | - Sharon Y Strauss
- Department of Evolution and Ecology, University of California Davis, One Shields Avenue, Davis, CA, USA
- Center for Population Biology, University of California Davis, One Shields Avenue, Davis, CA, USA
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16
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Wang HY, Zhang W, Dong JH, Wu H, Wang YH, Xiao HX. Optimization of SPME-GC-MS and characterization of floral scents from Aquilegia japonica and A. amurensis flowers. BMC Chem 2021; 15:26. [PMID: 33888127 PMCID: PMC8063332 DOI: 10.1186/s13065-021-00754-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 04/13/2021] [Indexed: 11/10/2022] Open
Abstract
Background The floral scents of plants play a key role in plant reproduction through the communication between plants and pollinators. Aquilegia as a model species for studying evolution, however, there have been few studies on the floral scents and relationships between floral scents and pollination for Aquilegia taxa. Methods In this study, three types of solid-phase micro-extraction (SPME) fiber coatings (DVB/PDMS, CAR/PDMS, DVB/CAR/PDMS) were evaluated for their performance in extracting volatile organic compounds (VOCs) from flowers of Aquilegia amurensis, which can contribute to the future studies of elucidating the role of floral scents in the pollination process. Results In total, 55 VOCs were identified, and among them, 50, 47 and 45 VOCs were extracted by the DVB/CAR/PDMS fiber, CAR/PDMS fiber and DVB/PDMS fibers, respectively. Only 30 VOCs were detected in A. japonica taxa. Furthermore, the relative contents of 8 VOCs were significant different (VIP > 1 and p < 0.05) between the A. amurensis and A. japonica. Conclusions The results can be applied in new studies of the relationships between the chemical composition of floral scents and the processes of attraction of pollinator. It may provide new ideas for rapid evolution and frequent interspecific hybridization of Aquilegia. Supplementary Information The online version contains supplementary material available at 10.1186/s13065-021-00754-1.
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Affiliation(s)
- Hua-Ying Wang
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun, 130024, China
| | - Wei Zhang
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun, 130024, China
| | - Jian-Hua Dong
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun, 130024, China
| | - Hao Wu
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun, 130024, China
| | - Yuan-Hong Wang
- Faculty of Chemistry, Northeast Normal University, Changchun, 130024, China
| | - Hong-Xing Xiao
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun, 130024, China.
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17
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Rose JP, Sytsma KJ. Complex interactions underlie the correlated evolution of floral traits and their association with pollinators in a clade with diverse pollination systems. Evolution 2021; 75:1431-1449. [PMID: 33818785 DOI: 10.1111/evo.14220] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 02/15/2021] [Accepted: 03/14/2021] [Indexed: 11/28/2022]
Abstract
Natural selection by pollinators is an important factor in the morphological diversity and adaptive radiation of flowering plants. Selection by similar pollinators in unrelated plants leads to convergence in floral morphology, or "floral syndromes." Previous investigations into floral syndromes have mostly studied relatively small and/or simple systems, emphasizing vertebrate pollination. Despite the importance of multiple floral traits in plant-pollinator interactions, these studies have examined few quantitative traits, so their co-variation and phenotypic integration have been underexplored. To gain better insights into pollinator-trait dynamics, we investigate the model system of the phlox family (Polemoniaceae), a clade of ∼400 species pollinated by a diversity of vectors. Using a comprehensive phylogeny and large dataset of traits and observations of pollinators, we reconstruct ancestral pollination system, accounting for the temporal history of pollinators. We conduct phylogenetically controlled analyses of trait co-variation and association with pollinators, integrating many analyses over phylogenetic uncertainty. Pollinator shifts are more heterogeneous than previously hypothesized. The evolution of floral traits is partially constrained by phylogenetic history and trait co-variation, but traits are convergent and differences are associated with different pollinators. Trait shifts are usually gradual, rather than rapid, suggesting complex genetic and ecological interactions of flowers at macroevolutionary scales.
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Affiliation(s)
- Jeffrey P Rose
- Department of Botany, University of Wisconsin-Madison, Madison, Wisconsin, 53706.,Current Address: Department of Biology, University of Nebraska at Kearney, Kearney, Nebraska, 68849
| | - Kenneth J Sytsma
- Department of Botany, University of Wisconsin-Madison, Madison, Wisconsin, 53706
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18
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Johnson SD, Sivechurran J, Doarsamy S, Shuttleworth A. Dung mimicry: the function of volatile emissions and corolla patterning in fly-pollinated Wurmbea flowers. THE NEW PHYTOLOGIST 2020; 228:1662-1673. [PMID: 33460187 DOI: 10.1111/nph.16791] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 06/26/2020] [Indexed: 06/12/2023]
Abstract
It has been suggested that flowers of some angiosperms mimic vertebrate faeces (dung) in order to exploit insect pollinators that utilize faeces as a source of food and/or oviposition sites. We investigated a potential case of mimicry in Wurmbea elatior (Colchicaceae), a lily that exhibits a faecal odour and pattern of dark spots on the corolla. We found that W. elatior is pollinated by a broad assemblage of coprophagous flies and is dependent on pollinator visits for seed production. The flowers emit volatiles that are characteristic of vertebrate faeces, and three of these compounds - skatole, indole, and an unidentified compound - elicited electrophysiological antennal responses from flies. Artificial flowers laced with indole and skatole or skatole alone attracted the same assemblage of flies as was recorded on flowers of W. elatior. Spotted artificial flowers attracted twice as many flies as did those lacking spots. Experimental addition of indole and skatole to flowers of Wurmbea kraussii, a congener with unscented flowers pollinated by hoverflies, induced a shift to an insect visitor assemblage dominated by coprophagous flies. This study clarifies the roles of volatile emissions (particularly skatole) and visual signals in floral dung mimicry.
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Affiliation(s)
- Steven D Johnson
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Post Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa
| | - Jadine Sivechurran
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Post Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa
| | - Sachin Doarsamy
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Post Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa
| | - Adam Shuttleworth
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Post Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa
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Powers JM, Seco R, Faiola CL, Sakai AK, Weller SG, Campbell DR, Guenther A. Floral Scent Composition and Fine-Scale Timing in Two Moth-Pollinated Hawaiian Schiedea (Caryophyllaceae). FRONTIERS IN PLANT SCIENCE 2020; 11:1116. [PMID: 32793267 PMCID: PMC7385411 DOI: 10.3389/fpls.2020.01116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
Floral scent often intensifies during periods of pollinator activity, but the degree of this synchrony may vary among scent compounds depending on their function. Related plant species with the same pollinator may exhibit similar timing and composition of floral scent. We compared timing and composition of floral volatiles for two endemic Hawaiian plant species, Schiedea kaalae and S. hookeri (Caryophyllaceae). For S. kaalae, we also compared the daily timing of emission of floral volatiles to evening visits of their shared pollinator, an endemic Hawaiian moth (Pseudoschrankia brevipalpis; Erebidae). The identity and amount of floral volatiles were measured in the greenhouse during day and evening periods with dynamic headspace sampling and GC-MS (gas chromatography - mass spectrometry). The timing of emissions (daily rise, peak, and fall) was measured by sampling continuously for multiple days in a growth chamber with PTR-MS (proton transfer reaction mass spectrometry). Nearly all volatiles detected underwent strong daily cycles in emission. Timings of floral volatile emissions were similar for S. kaalae and S. hookeri, as expected for two species sharing the same pollinator. For S. kaalae, many volatiles known to attract moths, including several linalool oxides and 2-phenylacetaldehyde, peaked within 2 h of the peak visitation time of the moth which pollinates both species. Floral volatiles of both species that peaked in the evening were also emitted several hours before and after the brief window of pollinator activity. Few volatiles followed a daytime emission pattern, consistent with increased apparency to visitors only at night. The scent blends of the two species differed in their major components and were most distinct from each other in the evening. The qualitative difference in evening scent composition between the two Schiedea species may reflect their distinct evolutionary history and may indicate that the moth species uses several different floral cues to locate rewards.
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Affiliation(s)
- John M. Powers
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
| | - Roger Seco
- Terrestrial Ecology Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Celia L. Faiola
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
| | - Ann K. Sakai
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
| | - Stephen G. Weller
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
| | - Diane R. Campbell
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
| | - Alex Guenther
- Department of Earth System Science, University of California, Irvine, Irvine, CA, United States
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20
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Gong WC, Xu SJ, Liu YH, Wang CM, Martin K, Meng LZ. Chemical composition of floral scents from three Plumeria rubra L. (Apocynaceae) forms linked to petal color proprieties. BIOCHEM SYST ECOL 2019. [DOI: 10.1016/j.bse.2019.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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21
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Chapurlat E, Ågren J, Anderson J, Friberg M, Sletvold N. Conflicting selection on floral scent emission in the orchid Gymnadenia conopsea. THE NEW PHYTOLOGIST 2019; 222:2009-2022. [PMID: 30767233 DOI: 10.1111/nph.15747] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 02/04/2019] [Indexed: 06/09/2023]
Abstract
Floral scent is a crucial trait for pollinator attraction. Yet only a handful of studies have estimated selection on scent in natural populations and no study has quantified the relative importance of pollinators and other agents of selection. In the fragrant orchid Gymnadenia conopsea, we used electroantennographic data to identify floral scent compounds detected by local pollinators and quantified pollinator-mediated selection on emission rates of 10 target compounds as well as on flowering start, visual display and spur length. Nocturnal pollinators contributed more to reproductive success than diurnal pollinators, but there was significant pollinator-mediated selection on both diurnal and nocturnal scent emission. Pollinators selected for increased emission of two compounds and reduced emission of two other compounds, none of which were major constituents of the total bouquet. In three cases, pollinator-mediated selection was opposed by nonpollinator-mediated selection, leading to weaker or no detectable net selection. Our study demonstrates that minor scent compounds can be targets of selection, that pollinators do not necessarily favour stronger scent signalling, and that some scent compounds are subject to conflicting selection from pollinators and other agents of selection. Hence, including floral scent traits into selection analysis is important for understanding the mechanisms behind floral evolution.
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Affiliation(s)
- Elodie Chapurlat
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 752 36, Uppsala, Sweden
| | - Jon Ågren
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 752 36, Uppsala, Sweden
| | - Joseph Anderson
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 752 36, Uppsala, Sweden
| | - Magne Friberg
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 752 36, Uppsala, Sweden
- Department of Biology, Lund University, SE-223 62, Lund, Sweden
| | - Nina Sletvold
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 752 36, Uppsala, Sweden
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Capitula essential oil composition of seven Centaurea species (sect. Acrocentron, Asteraceae) – Taxonomic implication and ecological significance. BIOCHEM SYST ECOL 2019. [DOI: 10.1016/j.bse.2019.01.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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23
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Campbell DR, Sosenski P, Raguso RA. Phenotypic plasticity of floral volatiles in response to increasing drought stress. ANNALS OF BOTANY 2019; 123:601-610. [PMID: 30364929 PMCID: PMC6417471 DOI: 10.1093/aob/mcy193] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 10/04/2018] [Indexed: 05/20/2023]
Abstract
BACKGROUND AND AIMS Flowers emit a wide range of volatile compounds which can be critically important to interactions with pollinators or herbivores. Yet most studies of how the environment influences plant volatiles focus on leaf emissions, with little known about abiotic sources of variation in floral volatiles. Understanding phenotypic plasticity in floral volatile emissions has become increasingly important with globally increasing temperatures and changes in drought frequency and severity. Here quantitative relationships of floral volatile emissions to soil water content were analysed. METHODS Plants of the sub-alpine herb Ipomopsis aggregata and hybrids with its closest congener were subjected to a progressive dry down, mimicking the range of soil moistures experienced in the field. Floral volatiles and leaf gas exchange were measured at four time points during the drought. KEY RESULTS As the soil dried, floral volatile emissions increased overall and changed in composition, from more 1,3-octadiene and benzyl alcohol to higher representation of some terpenes. Emissions of individual compounds were not linearly related to volumetric water content in the soil. The dominant compound, the monoterpene α-pinene, made up the highest percentage of the scent mixture when soil moisture was intermediate. In contrast, emission of the sesquiterpene (E,E)-α-farnesene accelerated as the drought became more intense. Changes in floral volatiles did not track the time course of changes in photosynthetic rate or stomatal conductance. CONCLUSIONS This study shows responses of specific floral volatile organic compounds to soil moisture. The non-linear responses furthermore suggest that extreme droughts may have impacts that are not predictable from milder droughts. Floral volatiles are likely to change seasonally with early summer droughts in the Rocky Mountains, as well as over years as snowmelt becomes progressively earlier. Changes in water availability may have impacts on plant-animal interactions that are mediated through non-linear changes in floral volatiles.
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Affiliation(s)
- Diane R Campbell
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA
- Rocky Mountain Biological Laboratory, Crested Butte, CO, USA
- For correspondence. E-mail
| | - Paula Sosenski
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA
- Rocky Mountain Biological Laboratory, Crested Butte, CO, USA
- CONACYT – Departamento de Ecología Tropical, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA
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Rubini Pisano A, Moré M, Cisternas MA, Raguso RA, Benitez-Vieyra S. Breakdown of species boundaries in Mandevilla: floral morphological intermediacy, novel fragrances and asymmetric pollen flow. PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:206-215. [PMID: 30317685 DOI: 10.1111/plb.12924] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 10/10/2018] [Indexed: 05/26/2023]
Abstract
Phenotypic intermediacy is an indicator of putative hybrid origin and has provided the main clues to discovering hybrid plants in nature. Mandevilla pentlandiana and M. laxa (Apocynaceae) are sister species with clear differences in floral phenotype and associated pollinator guilds: diurnal Hymenoptera and nocturnal hawkmoths, respectively. The presence of individuals with intermediate phenotypes in a wild population raises questions about the roles of visual and olfactory signals (i.e. corolla morphology and floral fragrances) as barriers to interbreeding, and how the breakdown of floral isolation occurs. We examined phenotypic variation in a mixed Mandevilla population, analysing the chemical composition of floral fragrances, characterising floral shape through geometric morphometrics and assessing individual grouping through taxonomically relevant traits and an unsupervised learning algorithm. We quantified the visitation frequencies of floral visitors and tracked their foraging movements using pollen analogues. The presence of morphologically intermediate individuals and pollen analogue movement suggested extensive hybridisation between M. laxa and M. pentlandiana, along with asymmetrical rates of backcrossing between these putative hybrids and M. laxa. Floral volatiles from putative hybrid individuals showed a transgressive phenotype, with additional compounds not emitted by either parental species. Our results suggest the presence of a hybrid swarm between sympatric M. pentlandiana and M. laxa and indicate that initial hybridisation events between these parental species are rare, but once they occur, visits between putative hybrids and M. laxa are common and facilitate continued introgression.
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Affiliation(s)
- A Rubini Pisano
- Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, México
- Instituto Multidisciplinario de Biología Vegetal (CONICET - Universidad Nacional de Córdoba), Córdoba, Argentina
| | - M Moré
- Instituto Multidisciplinario de Biología Vegetal (CONICET - Universidad Nacional de Córdoba), Córdoba, Argentina
| | - M A Cisternas
- Instituto Multidisciplinario de Biología Vegetal (CONICET - Universidad Nacional de Córdoba), Córdoba, Argentina
- Jardín Botánico Nacional, Viña del Mar, Chile
| | - R A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, USA
| | - S Benitez-Vieyra
- Instituto Multidisciplinario de Biología Vegetal (CONICET - Universidad Nacional de Córdoba), Córdoba, Argentina
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Kay KM, Zepeda AM, Raguso RA. Experimental sympatry reveals geographic variation in floral isolation by hawkmoths. ANNALS OF BOTANY 2019; 123:405-413. [PMID: 30032166 PMCID: PMC6344223 DOI: 10.1093/aob/mcy143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 07/06/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND AND AIMS Under a widely accepted model of pollinator-driven speciation, geographic variation in pollinator assemblage drives floral divergence and automatically causes reproductive isolation. Yet it is unclear whether divergent floral adaptation initially confers strong reproductive isolation, or whether that comes at later stages of speciation and requires other forms of reproductive isolation. This study uses a pair of recently diverged, interfertile and parapatric species in the genus Clarkia to determine whether adaptation to hawkmoths, a novel pollinator functional group, would automatically confer floral isolation upon sympatric contact. METHODS First, genetically based differences in floral traits between C. breweri and C. concinna that would be maintained upon migration are quantified. Then scenarios of experimental sympatry are constructed in which arrays of flowers are exposed to the novel pollinator, the hawkmoth Hyles lineata, and pollinator preference and heterospecific pollen transfer are assessed. Source populations from across the ranges of each species are used to understand how geographic variation in floral traits within species may affect floral isolation. KEY RESULTS Although H. lineata has never been observed visiting C. concinna in the wild, it regularly moves between species in experimental floral arrays. Hawkmoth preference and heterospecific pollen transfer vary both among moths and among geographic source locations of C. concinna. The strength of floral isolation in this system is related to variation in flower size, especially hypanthium tube width, and nectar reward among C. concinna forms. CONCLUSIONS Although C. breweri has adopted a novel hawkmoth pollination system, both ethological and mechanical floral isolation by hawkmoths are incomplete and vary according to the specific phenotype of the C. concinna source population. The results suggest that strong floral isolation is not automatically conferred by a pollinator shift and may require additional evolution of deterrent floral traits and habitat isolation that reduces the immediate spatial co-occurrence of young species.
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Affiliation(s)
- Kathleen M Kay
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Aubrey M Zepeda
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA
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Campbell DR, Faidiga A, Trujillo G. Clines in traits compared over two decades in a plant hybrid zone. ANNALS OF BOTANY 2018; 122:315-324. [PMID: 29800076 PMCID: PMC6070099 DOI: 10.1093/aob/mcy072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 04/17/2018] [Indexed: 05/30/2023]
Abstract
Background and Aims Clines in traits across hybrid zones reflect a balance between natural selection and gene flow. Changes over time in average values for traits, and especially the shapes of their clines, are rarely investigated in plants, but could result from evolution in an unstable hybrid zone. Differences in clines between floral and vegetative traits could indicate different strengths of divergent selection. Methods Five floral and two vegetative traits were measured in 12 populations along an elevational gradient spanning a natural hybrid zone between Ipomopsis aggregata and Ipomopsis tenuituba. We compared clines in the floral traits with those measured 25 years ago. Observed changes in mean trait values were compared with predictions based on prior estimates of natural selection. We also compared the steepness and position of clines between the floral and vegetative traits. Key Results Corolla length has increased over five generations to an extent that matches predictions from measurements of phenotypic selection and heritability. The shape of its cline, and that of other traits, has not changed detectably. Clines varied across traits, but not all floral traits showed steeper clines than did vegetative traits. Both suites of morphological traits had steeper clines than did neutral molecular markers. Conclusions The increase in corolla length provides a rare example of a match between predicted and observed evolution of a plant trait in natural populations. The clinal properties are consistent with the hypothesis that habitat-mediated divergent selection on vegetative traits and pollinator-mediated selection on floral traits both maintain species differences across the hybrid zone.
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Affiliation(s)
- Diane R Campbell
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA
- Rocky Mountain Biological Laboratory, Crested Butte, CO 81224, USA
| | | | - Gabriel Trujillo
- Rocky Mountain Biological Laboratory, Crested Butte, CO 81224, USA
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Burkle LA, Runyon JB. The smell of environmental change: Using floral scent to explain shifts in pollinator attraction. APPLICATIONS IN PLANT SCIENCES 2017; 5:apps1600123. [PMID: 28690928 PMCID: PMC5499301 DOI: 10.3732/apps.1600123] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 01/03/2017] [Indexed: 05/18/2023]
Abstract
As diverse environmental changes continue to influence the structure and function of plant-pollinator interactions across spatial and temporal scales, we will need to enlist numerous approaches to understand these changes. Quantitative examination of floral volatile organic compounds (VOCs) is one approach that is gaining popularity, and recent work suggests that floral VOCs hold substantial promise for better understanding and predicting the effects of environmental change on plant-pollinator interactions. Until recently, few ecologists were employing chemical approaches to investigate mechanisms by which components of environmental change may disrupt these essential mutualisms. In an attempt to make these approaches more accessible, we summarize the main field, laboratory, and statistical methods involved in capturing, quantifying, and analyzing floral VOCs in the context of changing environments. We also highlight some outstanding questions that we consider to be highly relevant to making progress in this field.
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Affiliation(s)
- Laura A. Burkle
- Department of Ecology, Montana State University, Bozeman, Montana 59717 USA
- Author for correspondence:
| | - Justin B. Runyon
- Rocky Mountain Research Station, USDA Forest Service, 1648 S. 7th Avenue, Bozeman, Montana 59717 USA
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28
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Roda F, Walter GM, Nipper R, Ortiz‐Barrientos D. Genomic clustering of adaptive loci during parallel evolution of an Australian wildflower. Mol Ecol 2017; 26:3687-3699. [DOI: 10.1111/mec.14150] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 03/07/2017] [Accepted: 04/03/2017] [Indexed: 12/11/2022]
Affiliation(s)
- Federico Roda
- School of Biological Sciences The University of Queensland St. Lucia QLD Australia
- Harvard University Boston MA USA
| | - Greg M. Walter
- School of Biological Sciences The University of Queensland St. Lucia QLD Australia
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29
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Borghi M, Fernie AR, Schiestl FP, Bouwmeester HJ. The Sexual Advantage of Looking, Smelling, and Tasting Good: The Metabolic Network that Produces Signals for Pollinators. TRENDS IN PLANT SCIENCE 2017; 22:338-350. [PMID: 28111171 DOI: 10.1016/j.tplants.2016.12.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 12/10/2016] [Accepted: 12/21/2016] [Indexed: 05/08/2023]
Abstract
A striking feature of the angiosperms that use animals as pollen carriers to sexually reproduce is the great diversity of their flowers with regard to morphology and traits such as color, odor, and nectar. These traits are underpinned by the synthesis of secondary metabolites such as pigments and volatiles, as well as carbohydrates and amino acids, which are used by plants to lure and reward animal pollinators. We review here the knowledge of the metabolic network that supports the biosynthesis of these compounds and the behavioral responses that these molecules elicit in the animal pollinators. Such knowledge provides us with a deeper insight into the ecology and evolution of plant-pollinator interactions, and should help us to better manage these ecologically essential interactions in agricultural ecosystems.
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Affiliation(s)
- Monica Borghi
- Laboratory of Plant Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Alisdair R Fernie
- Max-Planck-Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam-Golm, Germany
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, 8008 Zürich
| | - Harro J Bouwmeester
- Laboratory of Plant Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; Present address: Plant Hormone Biology group, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
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30
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Murúa M, Espíndola A, González A, Medel R. Pollinators and crossability as reproductive isolation barriers in two sympatric oil-rewarding Calceolaria (Calceolariaceae) species. Evol Ecol 2017. [DOI: 10.1007/s10682-017-9894-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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31
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Attraction of dung beetles to herbivore dung and synthetic compounds in a comparative field study. CHEMOECOLOGY 2017. [DOI: 10.1007/s00049-017-0232-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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32
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Gegear RJ, Burns R, Swoboda-Bhattarai KA. “Hummingbird” floral traits interact synergistically to discourage visitation by bumble bee foragers. Ecology 2017; 98:489-499. [DOI: 10.1002/ecy.1661] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 11/01/2016] [Accepted: 11/07/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Robert J. Gegear
- Department of Biology and Biotechnology; Worcester Polytechnic Institute; Worcester Massachusetts 01609-2280 USA
| | - Rebecca Burns
- Department of Biology and Biotechnology; Worcester Polytechnic Institute; Worcester Massachusetts 01609-2280 USA
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Cai J, Zu P, Schiestl FP. The molecular bases of floral scent evolution under artificial selection: insights from a transcriptome analysis in Brassica rapa. Sci Rep 2016; 6:36966. [PMID: 27841366 PMCID: PMC5107913 DOI: 10.1038/srep36966] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 10/13/2016] [Indexed: 12/24/2022] Open
Abstract
In an artificial selection experiment using fast-cycling Brassica rapa plants it was recently shown that floral VOCs respond rapidly to selection for increased amounts. Here we carried out transcriptome analysis in these plants to explore the molecular bases of the augmentation in the artificially selected scent compound, phenylacetaldehyde (PAA), as well as other compounds that increased through pleiotropy. In the transcriptome data, we found up-regulation of genes likely underlying PAA synthesis, but also several genes of the shikimate pathway and the related phenylalanine metabolism. As phenylalanine is the precursor of many aromatic volatiles that showed increased emission, this result could explain some of the pleiotropic evolutionary responses. In addition, we found that ribosomal protein genes were up-regulated in “high” (high PAA amount) selection line plants, a mechanism that might further augment the effect of elevated gene expression at the proteomic level. Our study shows that selection on an individual trait can impose changes in the expression of several different genes, which could explain pleiotropic responses in the biosynthetic network of floral volatiles.
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Affiliation(s)
- Jing Cai
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Pengjuan Zu
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
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34
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Jürgens A, Bischoff M. Changing odour landscapes: the effect of anthropogenic volatile pollutants on plant–pollinator olfactory communication. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12774] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Andreas Jürgens
- Department of Biology, Plant Chemical Ecology Technische Universität Darmstadt Schnittspahnstrasse 10 64287 Darmstadt Germany
- School of Life Sciences University of KwaZulu‐Natal P. Bag X01 Scottsville Pietermaritzburg3209 South Africa
| | - Mascha Bischoff
- Department of Biology, Plant Chemical Ecology Technische Universität Darmstadt Schnittspahnstrasse 10 64287 Darmstadt Germany
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Svensson GP, Raguso RA, Flatz R, Smith CI. Floral scent of Joshua trees (Yucca brevifolia sensu lato): Divergence in scent profiles between species but breakdown of signal integrity in a narrow hybrid zone. AMERICAN JOURNAL OF BOTANY 2016; 103:1793-1802. [PMID: 27578627 DOI: 10.3732/ajb.1600033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 05/13/2016] [Indexed: 05/14/2023]
Abstract
PREMISE OF THE STUDY The role of floral scent in facilitating reproductive isolation between closely related plants remains poorly understood. Yucca brevifolia and Yucca jaegeriana are pollinated by different moth species in allopatry, but in a narrow contact zone, pollinator-host specificity breaks down, resulting in hybridization between species. We explored the chemical basis for reproductive isolation and hybridization in these Joshua trees by characterizing the floral scent of each species in allopatry, analyzing scent profiles from trees in the contact zone, and matching these data with genotypic and phenotypic data. METHODS We analyzed floral volatiles using gas chromatography-mass spectrometry, tested for species divergence of scent profiles and classified trees in the contact zone as hybrid or either parental species. We used floral and vegetative morphological data and genotypic data to classify trees and analyzed whether certain trait combinations were more correlated than others with respect to assignment of trees and whether frequencies of classified tree types differed depending on which data set was used. KEY RESULTS The Joshua tree floral scent included oxygenated 8-carbon compounds not reported for other yuccas. The two species differed (P < 0.001) in scent profiles. In the contact zone, many hybrids were found, and phenotypic traits were generally weakly correlated, which may be explained by extensive gene flow between species or by exposure to different selection pressures. CONCLUSIONS Although the two Joshua tree species produce distinct floral scent profiles, it is insufficient to prevent attraction of associated pollinators to both hosts. Instead, floral morphology may be the key trait mediating gene flow between species.
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Affiliation(s)
- Glenn P Svensson
- Department of Biology, Lund University, Solvegatan 37, SE-22362 Lund Sweden
| | - Robert A Raguso
- Department of Neurobiology and Behavior, 215 Tower Road, Cornell University, Ithaca, New York 14853 USA
| | - Ramona Flatz
- Department of Biology, Willamette University, 900 State Street, Salem, Oregon 97301 USA
| | - Christopher I Smith
- Department of Biology, Willamette University, 900 State Street, Salem, Oregon 97301 USA
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36
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Milano ER, Kenney AM, Juenger TE. Adaptive differentiation in floral traits in the presence of high gene flow in scarlet gilia (
Ipomopsis aggregata
). Mol Ecol 2016; 25:5862-5875. [DOI: 10.1111/mec.13752] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 06/20/2016] [Accepted: 06/22/2016] [Indexed: 10/21/2022]
Affiliation(s)
- Elizabeth R. Milano
- Department of Integrative Biology The University of Texas at Austin 1 University Station C0930 Austin TX 78712 USA
| | - Amanda M. Kenney
- Department of Biological Sciences St. Edward's University 3001 S. Congress Ave. Austin TX 78704 USA
| | - Thomas E. Juenger
- Department of Integrative Biology The University of Texas at Austin 1 University Station C0930 Austin TX 78712 USA
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37
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Campbell DR, Jürgens A, Johnson SD. Reproductive isolation between Zaluzianskya species: the influence of volatiles and flower orientation on hawkmoth foraging choices. THE NEW PHYTOLOGIST 2016; 210:333-342. [PMID: 26536281 DOI: 10.1111/nph.13746] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/06/2015] [Indexed: 06/05/2023]
Abstract
Floral trait differences between related species may play a key role in reproductive isolation imposed by pollinators. Volatile emissions can influence pollinator choice, but how they act in combination with traits such as flower orientation is rarely studied. We compared flower-opening patterns, morphology, colour, orientation and volatile emissions for two closely related species of Zaluzianskya and their natural hybrids. Hawkmoth pollinators were tested for preference between flowers of the two species, and between flowers with manipulations of volatiles or orientation. Flowers of Z. natalensis and Z. microsiphon open at night and day, respectively, but they overlap during early evening, when hawkmoths showed a strong preference for Z. natalensis. The species have similar flower size and colour, but Z. natalensis emits more floral volatiles in the evening and presents flowers vertically face-up as opposed to horizontally in Z. microsiphon, whereas natural hybrids are intermediate. Adding methyl benzoate and linalool to flowers of Z. microsiphon did not increase hawkmoth attraction, but re-orientation of flowers to face vertically increased attraction when scent cues were present, whereas re-orientation of Z. natalensis flowers to face horizontally decreased attraction. This study highlights the importance of flower orientation in imposing reproductive isolation.
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Affiliation(s)
- Diane R Campbell
- Department of Ecology & Evolutionary Biology, University of California, Irvine, CA, 92697, USA
| | - Andreas Jürgens
- School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
- Plant Chemical Ecology, Technische Universität Darmstadt, Schnittspahnstrasse 4, 64287, Darmstadt, Germany
| | - Steven D Johnson
- School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
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Koski MH, Ashman TL. An altitudinal cline in UV floral pattern corresponds with a behavioral change of a generalist pollinator assemblage. Ecology 2015; 96:3343-53. [DOI: 10.1890/15-0242.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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39
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Chartier M, Liagre S, Weiss-Schneeweiss H, Kolano B, Bessière JM, Schönenberger J, Gibernau M. Floral traits and pollination ecology of European Arum hybrids. Oecologia 2015; 180:439-51. [DOI: 10.1007/s00442-015-3498-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 10/22/2015] [Indexed: 11/29/2022]
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40
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Larue AAC, Raguso RA, Junker RR. Experimental manipulation of floral scent bouquets restructures flower-visitor interactions in the field. J Anim Ecol 2015; 85:396-408. [PMID: 26428739 DOI: 10.1111/1365-2656.12441] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/19/2015] [Indexed: 11/29/2022]
Abstract
A common structural feature of natural communities is the non-random distribution of pairwise interactions between organisms of different trophic levels. For plant-animal interactions, it is predicted that both stochastic processes and functional plant traits that facilitate or prevent interactions are responsible for these patterns. However, unbiased manipulative field experiments that rigorously test the effects of individual traits on community structure are lacking. We address this gap by manipulating floral scent bouquets in the field. Manipulation of floral scent bouquets led to quantitative as well as qualitative restructuring of flower-visitor networks, making them more generalized. Olfactometer trials confirmed both positive and negative responses to scent bouquets. Our results clearly show that the distribution of insect visitors to the two abundant study plant species reflects the insects' species-specific preferences for floral scents, rather than for visual or morphological floral traits. Thus, floral scents may be of major importance in partitioning flower-visitor interactions. Integrating experimental manipulations of plant traits with field observations of interaction patterns thus represents a promising approach for revealing the processes that structure species assemblages in natural communities.
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Affiliation(s)
- Anne-Amélie C Larue
- Department of Ecology and Evolution, University Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Corson-Mudd Building, 215 Tower Road, Ithaca, NY, 14853, USA
| | - Robert R Junker
- Department of Ecology and Evolution, University Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria
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41
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Raguso RA, Thompson JN, Campbell DR. Improving our chemistry: challenges and opportunities in the interdisciplinary study of floral volatiles. Nat Prod Rep 2015; 32:893-903. [PMID: 25882132 DOI: 10.1039/c4np00159a] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The field of chemical ecology was established, in large part, through collaborative studies between biologists and chemists with common interests in the mechanisms that mediate chemical communication in ecological and evolutionary contexts. Pollination is one highly diverse and important category of such interactions, and there is growing evidence that floral volatiles play important roles in mediating pollinator behaviour and its consequences for plant reproductive ecology and evolution. Here we outline next-generation questions emerging in the study of plants and pollinators, and discuss the potential for strengthening collaboration between biologists and chemists in answering such questions.
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Affiliation(s)
- R A Raguso
- Department of Neurobiology and Behavior, Cornell University, 215 Tower Road, Ithaca, 14853, NY, USA.
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42
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The Influence of Prior Learning Experience on Pollinator Choice: An Experiment Using Bumblebees on Two Wild Floral Types of Antirrhinum majus. PLoS One 2015; 10:e0130225. [PMID: 26263186 PMCID: PMC4532467 DOI: 10.1371/journal.pone.0130225] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 05/17/2015] [Indexed: 12/04/2022] Open
Abstract
Understanding how pollinator behavior may influence pollen transmission across floral types is a major challenge, as pollinator decision depends on a complex range of environmental cues and prior experience. Here we report an experiment using the plant Antirrhinum majus and the bumblebee Bombus terrestris to investigate how prior learning experience may affect pollinator preferences between floral types when these are presented together. We trained naive bumblebees to forage freely on flowering individuals of either A. majus pseudomajus (magenta flowers) or A. majus striatum (yellow flowers) in a flight cage. We then used a Y-maze device to expose trained bumblebees to a dual choice between the floral types. We tested the influence of training on their choice, depending on the type of plant signals available (visual signals, olfactory signals, or both). Bumblebees had no innate preference for either subspecies. Bumblebees trained on the yellow-flowered subspecies later preferred the yellow type, even when only visual or only olfactory signals were available, and their preference was not reinforced when both signal types were available. In contrast, bumblebees trained on the magenta-flowered subspecies showed no further preference between floral types and took slightly more time to make their choice. Since pollinator constancy has been observed in wild populations of A. majus with mixed floral types, we suggest that such constancy likely relies on short-term memory rather than acquired preference through long-term memory induced by prior learning.
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Parachnowitsch AL, Manson JS. The chemical ecology of plant-pollinator interactions: recent advances and future directions. CURRENT OPINION IN INSECT SCIENCE 2015; 8:41-46. [PMID: 32846674 DOI: 10.1016/j.cois.2015.02.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 01/31/2015] [Accepted: 02/04/2015] [Indexed: 05/24/2023]
Abstract
Floral chemistry mediates plant-pollinator interactions through floral scents and reward components. Although improved techniques have increased interest in studying floral volatiles and nectar chemistry, these two foci have generally been studied in isolation. The ecological functions of floral chemistry have been relatively well studied and focused on pollinator behaviour. While studies comparing chemistry between plant parts and across phylogenies are increasing, work on the evolution of floral chemistry and the importance of community context in mediating pollinator responses is lacking. Future research should concentrate on more holistic studies that include both signal and reward chemistry to understand the relative contribution of these complex and dynamic floral traits to the ecology and evolution of plants and their pollinators.
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Affiliation(s)
- Amy L Parachnowitsch
- Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, 75236 Uppsala, Sweden.
| | - Jessamyn S Manson
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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