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Tunstad SA, Bull ID, Rands SA, Whitney HM. The cuticular wax composition and crystal coverage of leaves and petals differ in a consistent manner between plant species. Open Biol 2024; 14:230430. [PMID: 38806146 DOI: 10.1098/rsob.230430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 03/26/2024] [Indexed: 05/30/2024] Open
Abstract
Both leaves and petals are covered in a cuticle, which itself contains and is covered by cuticular waxes. The waxes perform various roles in plants' lives, and the cuticular composition of leaves has received much attention. To date, the cuticular composition of petals has been largely ignored. Being the outermost boundary between the plant and the environment, the cuticle is the first point of contact between a flower and a pollinator, yet we know little about how plant-pollinator interactions shape its chemical composition. Here, we investigate the general structure and composition of floral cuticular waxes by analysing the cuticular composition of leaves and petals of 49 plant species, representing 19 orders and 27 families. We show that the flowers of plants from across the phylogenetic range are nearly devoid of wax crystals and that the total wax load of leaves in 90% of the species is higher than that of petals. The proportion of alkanes is higher, and the chain lengths of the aliphatic compounds are shorter in petals than in leaves. We argue these differences are a result of adaptation to the different roles leaves and petals play in plant biology.
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Affiliation(s)
| | - Ian D Bull
- Organic Geochemistry Unit, School of Chemistry, University of Bristol , Bristol, UK
| | - Sean A Rands
- School of Biological Sciences, University of Bristol , Bristol, UK
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Rands SA, Whitney HM, Hempel de Ibarra N. Multimodal floral recognition by bumblebees. CURRENT OPINION IN INSECT SCIENCE 2023; 59:101086. [PMID: 37468044 DOI: 10.1016/j.cois.2023.101086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 07/10/2023] [Accepted: 07/13/2023] [Indexed: 07/21/2023]
Abstract
Flowers present information to their insect visitors in multiple simultaneous sensory modalities. Research has commonly focussed on information presented in visual and olfactory modalities. Recently, focus has shifted towards additional 'invisible' information, and whether information presented in multiple modalities enhances the interaction between flowers and their visitors. In this review, we highlight work that addresses how multimodality influences behaviour, focussing on work conducted on bumblebees (Bombus spp.), which are often used due to both their learning abilities and their ability to use multiple sensory modes to identify and differentiate between flowers. We review the evidence for bumblebees being able to use humidity, electrical potential, surface texture and temperature as additional modalities, and consider how multimodality enhances their performance. We consider mechanisms, including the cross-modal transfer of learning that occurs when bees are able to transfer patterns learnt in one modality to an additional modality without additional learning.
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Affiliation(s)
- Sean A Rands
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, United Kingdom.
| | - Heather M Whitney
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, United Kingdom
| | - Natalie Hempel de Ibarra
- Centre for Research in Animal Behaviour, Psychology, University of Exeter, Exeter EX4 4QG, United Kingdom
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3
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Cutts V, Hanz DM, Barajas-Barbosa MP, Schrodt F, Steinbauer MJ, Beierkuhnlein C, Denelle P, Fernández-Palacios JM, Gaüzère P, Grenié M, Irl SDH, Kraft N, Kreft H, Maitner B, Munoz F, Thuiller W, Violle C, Weigelt P, Field R, Algar AC. Links to rare climates do not translate into distinct traits for island endemics. Ecol Lett 2023; 26:504-515. [PMID: 36740842 DOI: 10.1111/ele.14169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 11/08/2022] [Accepted: 12/12/2022] [Indexed: 02/07/2023]
Abstract
Current models of island biogeography treat endemic and non-endemic species as if they were functionally equivalent, focussing primarily on species richness. Thus, the functional composition of island biotas in relation to island biogeographical variables remains largely unknown. Using plant trait data (plant height, leaf area and flower length) for 895 native species in the Canary Islands, we related functional trait distinctiveness and climate rarity for endemic and non-endemic species and island ages. Endemics showed a link to climatically rare conditions that is consistent with island geological change through time. However, functional trait distinctiveness did not differ between endemics and non-endemics and remained constant with island age. Thus, there is no obvious link between trait distinctiveness and occupancy of rare climates, at least for the traits measured here, suggesting that treating endemic and non-endemic species as functionally equivalent in island biogeography is not fundamentally wrong.
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Affiliation(s)
- Vanessa Cutts
- School of Geography, University of Nottingham, Nottingham, UK
- Conservation Science Group, Department of Zoology, University of Cambridge, Cambridge, UK
| | - Dagmar M Hanz
- Biogeography & Biodiversity Lab, Institute of Physical Geography, Goethe University Frankfurt, Frankfurt, Germany
| | - Martha Paola Barajas-Barbosa
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Department of Computer Science, Martin Luther University Halle-Wittenberg, Halle, Germany
| | | | - Manuel J Steinbauer
- Sport Ecology, Bayreuth Center for Sport Science (BaySpo) & Bayreuth Center of Ecology and Environmental Research (BayCEER), Bayreuth, Germany
| | - Carl Beierkuhnlein
- Department of Biogeography, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
| | - Pierre Denelle
- Biodiversity, Macroecology & Biogeography, University of Göttingen, Göttingen, Germany
| | - José María Fernández-Palacios
- Island Ecology and Biogeography Group, Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias, Universidad de La Laguna, Spain
| | - Pierre Gaüzère
- Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, LECA, Grenoble, France
| | - Matthias Grenié
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Leipzig University, Leipzig, Germany
| | - Severin D H Irl
- Biogeography & Biodiversity Lab, Institute of Physical Geography, Goethe University Frankfurt, Frankfurt, Germany
| | - Nathan Kraft
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, USA
| | - Holger Kreft
- Biodiversity, Macroecology & Biogeography, University of Göttingen, Göttingen, Germany
| | - Brian Maitner
- Department of Ecology and Evolutionary Biology, Tucson, Arizona, USA
| | | | - Wilfried Thuiller
- Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, LECA, Grenoble, France
| | - Cyrille Violle
- CEFE, University of Montpellier, CNRS, EPHE, IRD, Montpellier, France
| | - Patrick Weigelt
- Biodiversity, Macroecology & Biogeography, University of Göttingen, Göttingen, Germany
- Campus-Institut Data Science, Göttingen, Germany
- Centre of Biodiversity and Sustainable Land Use (CBL), University of Göttingen, Göttingen, Germany
| | - Richard Field
- School of Geography, University of Nottingham, Nottingham, UK
| | - Adam C Algar
- School of Geography, University of Nottingham, Nottingham, UK
- Department of Biology, Lakehead University, Thunder Bay, Ontario, Canada
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Salzman S, Dahake A, Kandalaft W, Valencia-Montoya WA, Calonje M, Specht CD, Raguso RA. Cone humidity is a strong attractant in an obligate cycad pollination system. Curr Biol 2023; 33:1654-1664.e4. [PMID: 37015222 DOI: 10.1016/j.cub.2023.03.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/06/2023] [Accepted: 03/08/2023] [Indexed: 04/05/2023]
Abstract
Studies of pollination biology often focus on visual and olfactory aspects of attraction, with few studies addressing behavioral responses and morphological adaptation to primary metabolic attributes. As part of an in-depth study of obligate nursery pollination of cycads, we find that Rhopalotria furfuracea weevils show a strong physiological response and behavioral orientation to the cone humidity of the host plant Zamia furfuracea in an equally sensitive manner to their responses to Z. furfuracea-produced cone volatiles. Our results demonstrate that weevils can perceive fine-scale differences in relative humidity (RH) and that individuals exhibit a strong behavioral preference for higher RH in binary choice assays. Host plant Z. furfuracea produces a localized cloud of higher than ambient humidity around both pollen and ovulate cones, and R. furfuracea weevils preferentially land at the zone of maximum humidity on ovulate cones, i.e., the cracks between rows of megasporophylls that provide access to the ovules. Moreover, R. furfuracea weevils exhibit striking antennal morphological traits associated with RH perception, suggesting the importance of humidity sensing in the evolution of this insect lineage. Results from this study suggest that humidity functions in a signal-like fashion in this highly specialized pollination system and help to characterize a key pollination-mediating trait in an ancient plant lineage.
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Affiliation(s)
- Shayla Salzman
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA; School of Integrative Plant Science, Section of Plant Biology and the L.H. Bailey Hortorium, Cornell University, Ithaca, NY 14853, USA.
| | - Ajinkya Dahake
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - William Kandalaft
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Wendy A Valencia-Montoya
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, USA
| | | | - Chelsea D Specht
- School of Integrative Plant Science, Section of Plant Biology and the L.H. Bailey Hortorium, Cornell University, Ithaca, NY 14853, USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
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Dahake A, Jain P, Vogt CC, Kandalaft W, Stroock AD, Raguso RA. A signal-like role for floral humidity in a nocturnal pollination system. Nat Commun 2022; 13:7773. [PMID: 36522313 PMCID: PMC9755274 DOI: 10.1038/s41467-022-35353-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Accepted: 11/29/2022] [Indexed: 12/23/2022] Open
Abstract
Previous studies have considered floral humidity to be an inadvertent consequence of nectar evaporation, which could be exploited as a cue by nectar-seeking pollinators. By contrast, our interdisciplinary study of a night-blooming flower, Datura wrightii, and its hawkmoth pollinator, Manduca sexta, reveals that floral relative humidity acts as a mutually beneficial signal in this system. The distinction between cue- and signal-based functions is illustrated by three experimental findings. First, floral humidity gradients in Datura are nearly ten-fold greater than those reported for other species, and result from active (stomatal conductance) rather than passive (nectar evaporation) processes. These humidity gradients are sustained in the face of wind and are reconstituted within seconds of moth visitation, implying substantial physiological costs to these desert plants. Second, the water balance costs in Datura are compensated through increased visitation by Manduca moths, with concomitant increases in pollen export. We show that moths are innately attracted to humid flowers, even when floral humidity and nectar rewards are experimentally decoupled. Moreover, moths can track minute changes in humidity via antennal hygrosensory sensilla but fail to do so when these sensilla are experimentally occluded. Third, their preference for humid flowers benefits hawkmoths by reducing the energetic costs of flower handling during nectar foraging. Taken together, these findings suggest that floral humidity may function as a signal mediating the final stages of floral choice by hawkmoths, complementing the attractive functions of visual and olfactory signals beyond the floral threshold in this nocturnal plant-pollinator system.
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Affiliation(s)
- Ajinkya Dahake
- grid.5386.8000000041936877XDepartment of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853 USA
| | - Piyush Jain
- grid.5386.8000000041936877XSibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853 USA
| | - Caleb C. Vogt
- grid.5386.8000000041936877XDepartment of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853 USA
| | - William Kandalaft
- grid.5386.8000000041936877XDepartment of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853 USA
| | - Abraham D. Stroock
- grid.5386.8000000041936877XSmith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853 USA
| | - Robert A. Raguso
- grid.5386.8000000041936877XDepartment of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853 USA
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Harrison AS, Rands SA. The Ability of Bumblebees Bombus terrestris (Hymenoptera: Apidae) to Detect Floral Humidity is Dependent Upon Environmental Humidity. ENVIRONMENTAL ENTOMOLOGY 2022; 51:1010-1019. [PMID: 35899458 PMCID: PMC9585368 DOI: 10.1093/ee/nvac049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Indexed: 06/15/2023]
Abstract
Flowers produce local humidity that is often greater than that of the surrounding environment, and studies have shown that insect pollinators may be able to use this humidity difference to locate and identify suitable flowers. However, environmental humidity is highly heterogeneous, and is likely to affect the detectability of floral humidity, potentially constraining the contexts in which it can be used as a salient communication pathway between plants and their pollinators. In this study, we use differential conditioning techniques on bumblebees Bombus terrestris audax (Harris) to explore the detectability of an elevated floral humidity signal when presented against different levels of environmental noise. Artificial flowers were constructed that could be either dry or humid, and individual bumblebees were presented with consistent rewards in either the humid or dry flowers presented in an environment with four levels of constant humidity, ranging from low (~20% RH) to highly saturated (~95% RH). Ability to learn was dependent upon both the rewarding flower type and the environment: the bumblebees were able to learn rewarding dry flowers in all environments, but their ability to learn humid rewarding flowers was dependent on the environmental humidity, and they were unable to learn humid rewarding flowers when the environment was highly saturated. This suggests that floral humidity might be masked from bumblebees in humid environments, suggesting that it may be a more useful signal to insect pollinators in arid environments.
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Affiliation(s)
- Amy S Harrison
- School of Biological Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, United Kingdom
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