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Wenzell KE, Zhang JY, Skogen KA, Fant JB. Adaptive generalization in pollination systems: Hawkmoths increase fitness to long-tubed flowers, but secondary pollinators remain important. Ecol Evol 2024; 14:e11443. [PMID: 38783846 PMCID: PMC11112297 DOI: 10.1002/ece3.11443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 05/02/2024] [Accepted: 05/03/2024] [Indexed: 05/25/2024] Open
Abstract
Selection on floral traits by animal pollinators is important in the evolution of flowering plants, yet whether floral divergence requires specialized pollination remains uncertain. Longer floral tubes, a trait associated with long-tongued pollinators, can also exclude other pollinators from accessing rewards, a potential mechanism for specialization. Across most of its range, Castilleja sessiliflora displays much longer corollas than most Castilleja species, though tube length varies geographically and correlates partially with hawkmoth visitation. To assess whether long corolla tubes reflect adaptation to hawkmoth pollinators, we performed a day/night pollinator exclusion experiment in nine natural populations that varied in corolla length across the range of C. sessiliflora and short-tubed members of the parapatric C. purpurea complex. We compared the fitness contributions of nocturnal and diurnal visitors, revealing that long-tubed populations visited predominantly by hawkmoths experienced greater fruit set at night, in contrast with short-tubed populations or those visited mainly by diurnal pollinators. Next, leveraging a range-wide multiyear dataset of pollinator visitation to these species, we identify that hawkmoth visitation is associated with increased fitness in long-tubed populations overall, and that long tubes are associated with less diverse visitor assemblages. Thus, long corollas represent an adaptation to hawkmoth pollination at the exclusion of diverse pollinators. Nonetheless, while hawkmoths were scarce in the northern range, secondary diurnal pollinators contributed to fruit set across the range, providing reproductive assurance despite possible trait mismatch. This study illustrates adaptive generalization in pollination systems and that floral divergence may proceed along a continuum of generalized and specialized pollinator interactions.
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Affiliation(s)
- Katherine E. Wenzell
- Botany DepartmentCalifornia Academy of SciencesSan FranciscoCaliforniaUSA
- Department of EntomologyUniversity of MarylandCollege ParkMarylandUSA
| | - Johnathan Y. Zhang
- Interdisciplinary Programs BioinformaticsBoston UniversityBostonMassachusettsUSA
| | - Krissa A. Skogen
- Department of Biological SciencesClemson UniversityClemsonSouth CarolinaUSA
| | - Jeremie B. Fant
- Program in Plant Biology and ConservationNorthwestern UniversityEvanstonIllinoisUSA
- Negaunee Institute for Plant Conservation Science and ActionChicago Botanic GardenGlencoeIllinoisUSA
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Mochizuki K, Okamoto T, Chen KH, Wang CN, Evans M, Kramer AT, Kawakita A. Adaptation to pollination by fungus gnats underlies the evolution of pollination syndrome in the genus Euonymus. ANNALS OF BOTANY 2023; 132:319-333. [PMID: 37610846 PMCID: PMC10583214 DOI: 10.1093/aob/mcad081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Accepted: 07/04/2023] [Indexed: 08/25/2023]
Abstract
BACKGROUND AND AIMS Dipteran insects are known pollinators of many angiosperms, but knowledge on how flies affect floral evolution is relatively scarce. Some plants pollinated by fungus gnats share a unique set of floral characters (dark red display, flat shape and short stamens), which differs from any known pollination syndromes. We tested whether this set of floral characters is a pollination syndrome associated with pollination by fungus gnats, using the genus Euonymus as a model. METHODS The pollinator and floral colour, morphology and scent profile were investigated for ten Euonymus species and Tripterygium regelii as an outgroup. The flower colour was evaluated using bee and fly colour vision models. The evolutionary association between fungus gnat pollination and each plant character was tested using a phylogenetically independent contrast. The ancestral state reconstruction was performed on flower colour, which is associated with fungus gnat pollination, to infer the evolution of pollination in the genus Euonymus. KEY RESULTS The red-flowered Euonymus species were pollinated predominantly by fungus gnats, whereas the white-flowered species were pollinated by bees, beetles and brachyceran flies. The colour vision analysis suggested that red and white flowers are perceived as different colours by both bees and flies. The floral scents of the fungus gnat-pollinated species were characterized by acetoin, which made up >90 % of the total scent in three species. Phylogenetically independent contrast showed that the evolution of fungus gnat pollination is associated with acquisition of red flowers, short stamens and acetoin emission. CONCLUSIONS Our results suggest that the observed combination of floral characters is a pollination syndrome associated with the parallel evolution of pollination by fungus gnats. Although the role of the red floral display and acetoin in pollinator attraction remains to be elucidated, our finding underscores the importance of fungus gnats as potential contributors to floral diversification.
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Affiliation(s)
- Ko Mochizuki
- Botanical Gardens, Graduate School of Science, The University of Tokyo, 3-7-1 Hakusan, Bunkyo-ku, Tokyo, Japan
| | - Tomoko Okamoto
- Faculty of Applied Biological Sciences, Gifu University, Yanagido 1-1, Gifu, Japan
| | - Kai-Hsiu Chen
- Department of Ecology and Evolution, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Chun-Neng Wang
- Department of Life Science, Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei 10617, Taiwan
| | - Matthew Evans
- Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL 60022, USA
| | - Andrea T Kramer
- Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL 60022, USA
| | - Atsushi Kawakita
- Botanical Gardens, Graduate School of Science, The University of Tokyo, 3-7-1 Hakusan, Bunkyo-ku, Tokyo, Japan
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Frachon L, Arrigo L, Rusman Q, Poveda L, Qi W, Scopece G, Schiestl FP. Putative Signals of Generalist Plant Species Adaptation to Local Pollinator Communities and Abiotic Factors. Mol Biol Evol 2023; 40:7043265. [PMID: 36795638 PMCID: PMC10015620 DOI: 10.1093/molbev/msad036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 01/31/2023] [Accepted: 02/08/2023] [Indexed: 02/17/2023] Open
Abstract
The reproductive success of flowering plants with generalized pollination systems is influenced by interactions with a diverse pollinator community and abiotic factors. However, knowledge about the adaptative potential of plants to complex ecological networks and the underlying genetic mechanisms is still limited. Based on a pool-sequencing approach of 21 natural populations of Brassica incana in Southern Italy, we combined a genome-environmental association analysis with a genome scan for signals of population genomic differentiation to discover genetic variants associated with the ecological variation. We identified genomic regions putatively involved in the adaptation of B. incana to the identity of local pollinator functional categories and pollinator community composition. Interestingly, we observed several shared candidate genes associated with long-tongue bees, soil texture, and temperature variation. We established a genomic map of potential generalist flowering plant local adaptation to complex biotic interactions, and the importance of considering multiple environmental factors to describe the adaptive landscape of plant populations.
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Affiliation(s)
| | - Luca Arrigo
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Quint Rusman
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Lucy Poveda
- Functional Genomics Center Zurich, ETH Zurich/University of Zurich, Zurich, Switzerland
| | - Weihong Qi
- Functional Genomics Center Zurich, ETH Zurich/University of Zurich, Zurich, Switzerland
- SIB Swiss Institute of Bioinformatics, 1202 Geneva, Switzerland
| | - Giovanni Scopece
- Department of Biology, University of Naples Federico II, Complesso Universitario MSA, Naples, Italy
- NBFC: National Biodiversity Future Center, Palermo 90133, Italy
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
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van der Niet T, Egan PA, Schlüter PM. Evolutionarily inspired solutions to the crop pollination crisis. Trends Ecol Evol 2023; 38:435-445. [PMID: 36737302 DOI: 10.1016/j.tree.2022.12.010] [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: 05/31/2022] [Revised: 12/16/2022] [Accepted: 12/21/2022] [Indexed: 02/04/2023]
Abstract
The global decline in insect diversity threatens pollination services, potentially impacting crop production and food security. Here, we argue that this looming pollination crisis is generally approached from an ecological standpoint, and that consideration of evolutionary principles offers a novel perspective. First, we outline that wild plant species have overcome 'pollination crises' throughout evolutionary history, and show how associated principles can be applied to crop pollination. We then highlight technological advances that can be used to adapt crop flowers for optimal pollination by local wild pollinators, especially by increasing generalization in pollination systems. Thus, synergies among fundamental evolutionary research, genetic engineering, and agro-ecological science provide a promising template for addressing a potential pollination crisis, complementing much-needed strategies focused on pollinator conservation.
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Affiliation(s)
- Timotheüs van der Niet
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, P. Bag X01, 3209, Scottsville, Pietermaritzburg, South Africa.
| | - Paul A Egan
- Department of Plant Protection Biology, Swedish University of Agricultural Sciences, 230 53 Alnarp, Sweden
| | - Philipp M Schlüter
- Department of Plant Evolutionary Biology, Institute of Biology, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany
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Wenzell KE, Skogen KA, Fant JB. Range‐wide floral trait variation reflects shifts in pollinator assemblages, consistent with pollinator‐mediated divergence despite generalized visitation. OIKOS 2023. [DOI: 10.1111/oik.09708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Katherine E. Wenzell
- John Innes Centre Colney Lane Norwich UK
- Northwestern Univ., Program in Plant Biology and Conservation Evanston IL USA
- Negaunee Inst. for Plant Conservation Science and Action, Chicago Botanic Garden Glencoe IL USA
| | - Krissa A. Skogen
- Northwestern Univ., Program in Plant Biology and Conservation Evanston IL USA
- Negaunee Inst. for Plant Conservation Science and Action, Chicago Botanic Garden Glencoe IL USA
- Clemson Univ., Dept of Biological Sciences Clemson SC USA
| | - Jeremie B. Fant
- Northwestern Univ., Program in Plant Biology and Conservation Evanston IL USA
- Negaunee Inst. for Plant Conservation Science and Action, Chicago Botanic Garden Glencoe IL USA
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Kiepiel I, Brown M, Johnson SD. A generalized bird pollination system in Schotia brachypetala (Fabaceae). PLANT BIOLOGY (STUTTGART, GERMANY) 2022; 24:806-814. [PMID: 35500151 DOI: 10.1111/plb.13433] [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: 02/15/2022] [Accepted: 04/24/2022] [Indexed: 06/14/2023]
Abstract
Bird pollination systems are diverse, ranging from narrow-tubed flowers pollinated by specialist nectarivores such as hummingbirds and sunbirds, to relatively open flowers pollinated by opportunistic (i.e. generalist) nectarivores. The role of opportunistic avian nectarivores as pollinators has historically been under-appreciated. A key aspect to understanding the importance of opportunistic birds as pollinators is to investigate how efficiently they transfer pollen among flowers. Here, we document the pollination and breeding systems of Schotia brachypetala, a southern African tree known as the 'weeping boer-bean' on account of its prolific production of dilute hexose-dominated nectar. The cup-shaped flowers of this tree attract a large number of bird species, including both opportunistic and specialist nectarivores. We identified floral visitors using observations and camera traps and quantified the floral traits responsible for animal attraction. We documented the breeding system, used selective pollinator exclusion to test the contribution of birds to fecundity, and performed supplemental pollination to test for pollen limitation. Single-visit pollen deposition trials were undertaken to determine the efficacy of bird pollinators. Controlled hand-pollination experiments showed that S. brachypetala is genetically self-incompatible and therefore dependent on pollinators for seed production. Supplemental hand-pollination experiments showed that natural fecundity is limited by either the amount and/or the quality of pollen on stigmas. Flowers from which birds but not insects were experimentally excluded set fewer seeds than open control flowers. Opportunistic birds deposited more pollen per visit than did specialist sunbirds. We conclude that S. brachypetala has a generalized bird pollination system that mainly involves opportunistic nectarivores.
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Affiliation(s)
- I Kiepiel
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
| | - M Brown
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
| | - S D Johnson
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
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Miladin JR, Steven JC, Collar DC. A Comparative Approach to Understanding Floral Adaptation to Climate and Pollinators During Diversification in European and Mediterranean Silene. Integr Comp Biol 2022; 62:icac118. [PMID: 35816463 DOI: 10.1093/icb/icac118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Pollinator selection on floral traits is a well-studied phenomenon, but less is known about the influence of climate on this species interaction. Floral trait evolution could be a result of both adaptation to climate and pollinator-mediated selection. In addition, climate may also determine pollinator communities, leading to an indirect influence of climate on floral traits. In this study, we present evidence of both direct and indirect effects of climate on plant morphology through a phylogenetic comparative analysis of the relationships between climate, pollinators, and morphology in 89 European and Mediterranean Silene species. Climate directly influences vegetative morphology, where both leaf size and internode length were found to be smaller in habitats that are warmer in the driest quarter of the year and that have more precipitation in the coldest quarter of the year. Similarly, flower size was directly influenced by climate, where smaller calyxes were also associated with habitats that are warmer in the driest quarter of the year. These results suggest that reduced leaf and flower size promote water conservation in species that occupy arid climates. Floral traits also evolved in response to pollinators, with elongated calyxes associated with nocturnal pollination, though we also found evidence that climate influences pollinator distribution. Nocturnal pollinators of Silene are found in habitats that have more temperature evenness across seasons than diurnal pollinators. Correspondingly, nocturnally-pollinated Silene are more likely to occur in habitats that have lower daily temperature fluctuation and more temperature evenness across seasons. Altogether these results show that climate can directly influence vegetative and floral morphology, but it can also affect pollinator distribution, which in turn drives floral adaptation. Our study therefore suggests that climate mediates the influence of species interactions on trait evolution by imposing direct selective demands on floral phenotypes and by determining the pollinator community that imposes its own selective demands on flowers.
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Affiliation(s)
- Jenna R Miladin
- Avenue of the Arts, Department of Organismal and Environmental Biology, Christopher Newport University, Newport News, Virginia 23606
| | - Janet C Steven
- Avenue of the Arts, Department of Organismal and Environmental Biology, Christopher Newport University, Newport News, Virginia 23606
| | - David C Collar
- Avenue of the Arts, Department of Organismal and Environmental Biology, Christopher Newport University, Newport News, Virginia 23606
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McPeek SJ, Bronstein JL, McPeek MA. Eco-evolutionary feedbacks among pollinators, herbivores, and their plant resources. Evolution 2022; 76:1287-1300. [PMID: 35420697 PMCID: PMC9321553 DOI: 10.1111/evo.14492] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 03/19/2022] [Accepted: 03/23/2022] [Indexed: 01/21/2023]
Abstract
Eco-evolutionary feedbacks among multiple species occur when one species affects another species' evolution via its effects on the abundance and traits of a shared partner species. What happens if those two species enact opposing effects on their shared partner's population growth? Furthermore, what if those two kinds of interactions involve separate traits? For example, many plants produce distinct suites of traits that attract pollinators (mutualists) and deter herbivores (antagonists). Here, we develop a model to explore how pollinators and herbivores may influence each other's interactions with a shared plant species via evolutionary effects on the plant's nectar and toxin traits. The model results predict that herbivores indirectly select for the evolution of increased nectar production by suppressing plant population growth. The model also predicts that pollinators indirectly select for the evolution of increased toxin production by plants and increased counterdefenses by herbivores via their positive effects on plant population growth. Unless toxins directly affect pollinator foraging, plants always evolve increases in attraction and defense traits when they interact with both kinds of foragers. This work highlights the value of incorporating ecological dynamics to understand the entangled evolution of mutualisms and antagonisms in natural communities.
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Affiliation(s)
- Sarah J. McPeek
- Department of BiologyUniversity of VirginiaCharlottesvilleVA22904USA
| | - Judith L. Bronstein
- Department of Ecology & Evolutionary BiologyUniversity of ArizonaTucsonAZ85721USA
| | - Mark A. McPeek
- Department of Biological SciencesDartmouth CollegeHanoverNH03755USA
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Baczyński J, Sauquet H, Spalik K. Exceptional evolutionary lability of flower-like inflorescences (pseudanthia) in Apiaceae subfamily Apioideae. AMERICAN JOURNAL OF BOTANY 2022; 109:437-455. [PMID: 35112711 PMCID: PMC9310750 DOI: 10.1002/ajb2.1819] [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: 08/27/2021] [Revised: 12/19/2021] [Accepted: 12/22/2021] [Indexed: 06/14/2023]
Abstract
PREMISE Pseudanthia are widespread and have long been postulated to be a key innovation responsible for some of the angiosperm radiations. The aim of our study was to analyze macroevolutionary patterns of these flower-like inflorescences and their potential correlation with diversification rates in Apiaceae subfamily Apioideae. In particular, we were interested to investigate evolvability of pseudanthia and evaluate their potential association with changes in the size of floral display. METHODS The framework for our analyses consisted of a time-calibrated phylogeny of 1734 representatives of Apioideae and a morphological matrix of inflorescence traits encoded for 847 species. Macroevolutionary patterns in pseudanthia were inferred using Markov models of discrete character evolution and stochastic character mapping, and a principal component analysis was used to visualize correlations in inflorescence architecture. The interdependence between net diversification rates and the occurrence of pseudocorollas was analyzed with trait-independent and trait-dependent approaches. RESULTS Pseudanthia evolved in 10 major clades of Apioideae with at least 36 independent origins and 46 reversals. The morphospace analysis recovered differences in color and compactness between floral and hyperfloral pseudanthia. A correlation between pseudocorollas and size of inflorescence was also strongly supported. Contrary to our predictions, pseudanthia are not responsible for variation in diversification rates identified in this subfamily. CONCLUSIONS Our results suggest that pseudocorollas evolve as an answer to the trade-off between enlargement of floral display and costs associated with production of additional flowers. The high evolvability and architectural differences in apioid pseudanthia may be explained on the basis of adaptive wandering and evolutionary developmental biology.
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Affiliation(s)
- Jakub Baczyński
- Institute of Evolutionary Biology, Faculty of BiologyUniversity of Warsaw Biological and Chemical Research CentreWarsawPoland
| | - Hervé Sauquet
- National Herbarium of New South Wales (NSW)Royal Botanic Gardens and Domain TrustSydneyNSW2000Australia
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental SciencesUniversity of New South WalesSydneyAustralia
| | - Krzysztof Spalik
- Institute of Evolutionary Biology, Faculty of BiologyUniversity of Warsaw Biological and Chemical Research CentreWarsawPoland
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