1
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McCarren S, Midgley JJ, Coetzee A, Johnson SD. Pollen transfer efficiency in Erica depends on type of pollinator. PHYTOKEYS 2024; 244:237-248. [PMID: 39086738 PMCID: PMC11289515 DOI: 10.3897/phytokeys.244.107288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 04/15/2024] [Indexed: 08/02/2024]
Abstract
Pollen transfer efficiency (PTE; the proportion of pollen removed from flowers that reaches conspecific stigmas) is expected to vary with the type of pollinator and flower morphology, and to influence male siring success. Many species in the genus Erica are pollinated by bees (which consume pollen and should thus lower PTE) but during its radiation in the Cape, several independent shifts to both sunbird and long-proboscid fly (LP fly) pollinators, which do not consume pollen have taken place. Improvements in PTE could be one of the factors driving these pollinator shifts. PTE data for 15 Erica species (five for each of the three pollinator types) were collected and compared in relation to type of pollinator and anther exsertion. LP fly- and bird-pollinated species had higher PTE in comparison with bee-pollinated species. Species with inserted anthers had higher PTE than those with exserted anthers. This suggests that sunbirds and LP flies are more efficient pollinators than bees. Additionally, the study suggests that insertion of anthers within the corolla tube can reduce pollen losses.
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Affiliation(s)
- Sam McCarren
- Department of Biological Sciences, University of Cape Town, 7701 Cape Town, South AfricaUniversity of Cape TownCape TownSouth Africa
| | - Jeremy J. Midgley
- Department of Biological Sciences, University of Cape Town, 7701 Cape Town, South AfricaUniversity of Cape TownCape TownSouth Africa
| | - Anina Coetzee
- Department of Conservation Management, Nelson Mandela University, 6530 George, South AfricaNelson Mandela UniversityGeorgeSouth Africa
| | - Steven D. Johnson
- Centre for Functional Biodiversity School of Life Sciences, University of Kwazulu-Natal, 3209 Pietermaritzburg, South AfricaUniversity of Kwazulu-NatalPietermaritzburgSouth Africa
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2
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Simón-Porcar V, Escudero M, Santos-Gally R, Sauquet H, Schönenberger J, Johnson SD, Arroyo J. Convergent evolutionary patterns of heterostyly across angiosperms support the pollination-precision hypothesis. Nat Commun 2024; 15:1237. [PMID: 38336937 PMCID: PMC10858259 DOI: 10.1038/s41467-024-45118-0] [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: 02/14/2023] [Accepted: 01/12/2024] [Indexed: 02/12/2024] Open
Abstract
Since the insights by Charles Darwin, heterostyly, a floral polymorphism with morphs bearing stigmas and anthers at reciprocal heights, has become a model system for the study of natural selection. Based on his archetypal heterostylous flower, including regular symmetry, few stamens and a tube, Darwin hypothesised that heterostyly evolved to promote outcrossing through efficient pollen transfer between morphs involving different areas of a pollinator's body, thus proposing his seminal pollination-precision hypothesis. Here we update the number of heterostylous and other style-length polymorphic taxa to 247 genera belonging to 34 families, notably expanding known cases by 20%. Using phylogenetic and comparative analyses across the angiosperms, we show numerous independent origins of style-length polymorphism associated with actinomorphic, tubular flowers with a low number of sex organs, stamens fused to the corolla, and pollination by long-tongued insects. These associations provide support for the Darwinian pollination-precision hypothesis as a basis for convergent evolution of heterostyly across angiosperms.
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Affiliation(s)
- Violeta Simón-Porcar
- Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, E-41080, Sevilla, Spain.
- School of Life Sciences, University of KwaZulu-Natal, P Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa.
| | - Marcial Escudero
- Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, E-41080, Sevilla, Spain
| | | | - Hervé Sauquet
- National Herbarium of New South Wales, Royal Botanic Gardens and Domain Trust, Sydney, NSW, Australia
| | - Jürg Schönenberger
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030, Vienna, Austria
| | - Steven D Johnson
- School of Life Sciences, University of KwaZulu-Natal, P Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa
| | - Juan Arroyo
- Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, E-41080, Sevilla, Spain.
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3
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Mukhopadhyay A, Quader S. Pollination inaccuracy: estimating male fitness in the movement-assisted dichogamous species Clerodendrum infortunatum. Evol Ecol 2022. [DOI: 10.1007/s10682-022-10221-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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4
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Opedal ØH, Hildesheim LS, Armbruster WS. Evolvability and constraint in the evolution of three-dimensional flower morphology. AMERICAN JOURNAL OF BOTANY 2022; 109:1906-1917. [PMID: 36371715 PMCID: PMC9827957 DOI: 10.1002/ajb2.16092] [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: 12/21/2021] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 05/31/2023]
Abstract
PREMISE Flower phenotypes evolve to attract pollinators and to ensure efficient pollen transfer to and from the bodies of pollinators or, in self-compatible bisexual flowers, between anthers and stigmas. If functionally interacting traits are genetically correlated, response to selection may be subject to genetic constraints. Genetic constraints can be assessed by quantifying standing genetic variation in (multivariate) phenotypic traits and by asking how much the available variation is reduced under specific assumptions about phenotypic selection on functionally interacting and genetically correlated traits. METHODS We evaluated multivariate evolvability and potential genetic constraints underlying the evolution of the three-dimensional structure of Dalechampia blossoms. First, we used data from a greenhouse crossing design to estimate the G matrix for traits representing the relative positions of male and female sexual organs (anthers and stigmas) and used the G matrix to ask how genetic variation is distributed in multivariate space. To assess the evolutionary importance of genetic constraints, we related standing genetic variation across phenotypic space to evolutionary divergence of population and species in the same phenotypic directions. RESULTS Evolvabilities varied substantially across phenotype space, suggesting that certain traits or trait combinations may be subject to strong genetic constraint. Traits involved functionally in flower-pollinator fit and autonomous selfing exhibited considerable independent evolutionary potential, but population and species divergence tended to occur in phenotypic directions associated with greater-than-average evolvability. CONCLUSIONS These results are consistent with the hypothesis that genetic constraints can hamper joint trait evolution towards optimum flower-pollinator fit and optimum self-pollination rates.
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Affiliation(s)
| | | | - W. Scott Armbruster
- School of Biological SciencesUniversity of PortsmouthPortsmouthPO1 2DYUK
- Institute of Arctic BiologyUniversity of Alaska FairbanksFairbanksAK99775USA
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5
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Armbruster WS. Floral specialization increases pollination precision: the roles of floral orientation, symmetry, fusion and stamen number. THE NEW PHYTOLOGIST 2022; 235:1307-1309. [PMID: 35621012 DOI: 10.1111/nph.18215] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Affiliation(s)
- W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth, PO1 2DY, UK
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
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6
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Dellinger AS, Artuso S, Fernández-Fernández DM, Schönenberger J. Stamen dimorphism in bird-pollinated flowers: Investigating alternative hypotheses on the evolution of heteranthery. Evolution 2021; 75:2589-2599. [PMID: 33963764 DOI: 10.1111/evo.14260] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/19/2021] [Accepted: 04/27/2021] [Indexed: 01/09/2023]
Abstract
Heteranthery, the presence of distinct stamen types within a flower, is commonly explained as functional adaptation to alleviate the "pollen dilemma," defined as the dual and conflicting function of pollen as pollinator food resource and male reproductive agent. A single primary hypothesis, "division of labor," has been central in studies on heteranthery. This hypothesis postulates that one stamen type functions in rewarding pollen-collecting pollinators and the other in reproduction, thereby minimizing pollen loss. Only recently, alternative functions (i.e., staggered pollen release), were proposed, but comparative and experimental investigations are lagging behind. Here, we used 63 species of the tribe Merianieae (Melastomataceae) to demonstrate that, against theory, heteranthery occurs in flowers offering rewards other than pollen, such as staminal food bodies or nectar. Although shifts in reward type released species from the "pollen dilemma," heteranthery has evolved repeatedly de novo in food-body-rewarding, passerine-pollinated flowers. We used field investigations to show that foraging passerines discriminated between stamen types and removed large stamens more quickly than small stamens. Passerines removed small stamens on separate visits towards the end of flower anthesis. We propose that the staggered increase in nutritive content of small stamens functions to increase chances for outcross-pollen transfer.
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Affiliation(s)
| | - Silvia Artuso
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | | | - Jürg Schönenberger
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
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7
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Navarro L, Ayensa G, Sánchez JM. Efficiency of Herkogamy in Narcissus bulbocodium (Amaryllidaceae). PLANTS 2021; 10:plants10040648. [PMID: 33805464 PMCID: PMC8065898 DOI: 10.3390/plants10040648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 03/11/2021] [Accepted: 03/26/2021] [Indexed: 11/24/2022]
Abstract
Within the theoretical framework of the correlation pleiades, floral phenotypic integration has been proposed as a consequence of selection mediated by pollinators acting on floral characters. Here, we analyzed that assumption by studying the floral biology and pollination of the late-winter species Narcissus bulbocodium L. We found that the flowers of N. bulbocodium are pollinator-dependent (mainly on Bombus terrestris) in terms of achieving optimal levels of seed production (xenogamy mean seed-to-ovule ratio 64%). Flowers are phenotypically integrated, and only the inclusion of the stigma within the corona seems to have a positive and significant influence on the deposition of the pollen. It has been hypothesized that by including the stigma within the corolla, the flower has some control over the contact between stigma and pollinators that could lead to an “ordered herkogamy” as a way to promote outcross and avoid self-interference. Therefore, herkogamy was also studied, and while most previous studies have assessed the evolutionary significance of herkogamy by considering its relationship with outcrossing rates, we approach this phenomenon from a novel direction assessing the relationship between a proxy for herkogamy and the precision of the pollination process. Our results seem to support the existence of an optimal herkogamy distance that could maintain maximum levels of both pollen export and (cross) pollen capture. On the basis of the broad variability of herkogamy that we have found in N. bulbocodium and other data in the literature, we discuss the universality of the adaptive origin of herkogamy.
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8
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Castañeda-Zárate M, Johnson SD, van der Niet T. Food Reward Chemistry Explains a Novel Pollinator Shift and Vestigialization of Long Floral Spurs in an Orchid. Curr Biol 2021; 31:238-246.e7. [DOI: 10.1016/j.cub.2020.10.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 10/02/2020] [Accepted: 10/08/2020] [Indexed: 12/18/2022]
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9
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Albertsen E, Opedal ØH, Bolstad GH, Pérez-Barrales R, Hansen TF, Pélabon C, Armbruster WS. Using ecological context to interpret spatiotemporal variation in natural selection. Evolution 2020; 75:294-309. [PMID: 33230820 DOI: 10.1111/evo.14136] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/20/2020] [Accepted: 10/03/2020] [Indexed: 12/14/2022]
Abstract
Spatiotemporal variation in natural selection is expected, but difficult to estimate. Pollinator-mediated selection on floral traits provides a good system for understanding and linking variation in selection to differences in ecological context. We studied pollinator-mediated selection in five populations of Dalechampia scandens (Euphorbiaceae) in Costa Rica and Mexico. Using a nonlinear path-analytical approach, we assessed several functional components of selection, and linked variation in pollinator-mediated selection across time and space to variation in pollinator assemblages. After correcting for estimation error, we detected moderate variation in net selection on two out of four blossom traits. Both the opportunity for selection and the mean strength of selection decreased with increasing reliability of cross-pollination. Selection for pollinator attraction was consistently positive and stronger on advertisement than reward traits. Selection on traits affecting pollen transfer from the pollinator to the stigmas was strong only when cross-pollination was unreliable and there was a mismatch between pollinator and blossom size. These results illustrate how consideration of trait function and ecological context can facilitate both the detection and the causal understanding of spatiotemporal variation in natural selection.
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Affiliation(s)
- Elena Albertsen
- Norwegian Institute for Bioeconomy Research, Trondheim, 7031, Norway.,Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, 7491, Norway
| | - Øystein H Opedal
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, 7491, Norway.,Department of Biology, Lund University, Lund, SE-22362, Sweden
| | - Geir H Bolstad
- Norwegian Institute for Nature Research (NINA), Trondheim, 7485, Norway
| | - Rocío Pérez-Barrales
- School of Biological Sciences, University of Portsmouth, Portsmouth, PO1 2DY, United Kingdom
| | - Thomas F Hansen
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, Oslo, 0316, Norway
| | - Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, 7491, Norway
| | - W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth, PO1 2DY, United Kingdom.,Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, 99775, USA
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10
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Armbruster WS, Muchhala N. Floral reorientation: the restoration of pollination accuracy after accidents. THE NEW PHYTOLOGIST 2020; 227:232-243. [PMID: 32252125 DOI: 10.1111/nph.16482] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 01/11/2020] [Indexed: 05/28/2023]
Abstract
Plants sometimes suffer mechanical injury. The nonlethal collapse of a flowering stalk, for example, can greatly reduce plant fitness if it leads to 'incorrect' floral orientation and thus reduced visitation or poor pollination. When floral orientation is important for accurate pollination, as has been suggested for bilaterally symmetrical flowers, we predict that such flowers should have developmental and/or behavioural mechanisms for restoring 'correct' orientation after accidents. We made observations and conducted experiments on 23 native and cultivated flowering plant species in Australia, South America, North America and Europe. We found that flowers with bilateral symmetry usually have the capacity to reorient after accidents, and that this is manifested through rapid bending and/or rotation of pedicels or sexual organs or slower peduncle bending. Floral reorientation restores pollination accuracy and fit with pollinators. However, experimental floral misorientation in eight species with radially symmetrical flowers showed that, with one exception, they had little capacity to reorient their flowers, in line with expectations that the orientation of radially symmetrical flowers does not substantially affect pollination accuracy. Our results suggest that quick corrective reorientation of bilaterally symmetrical flowers is adaptive, highlighting a little-studied aspect of plant-pollinator interactions and plant evolution.
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Affiliation(s)
- W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth, PO1 2DY, UK
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, 99775-7000, USA
| | - Nathan Muchhala
- Department of Biology, University of Missouri-St Louis, St Louis, MO, 63121-4499, USA
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11
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Zhou T, Zhang W, Zhang D, El-Kassaby YA, Fan J, Jiang H, Wang G, Cao F. A Binary-Based Matrix Model for Malus Corolla Symmetry and Its Variational Significance. FRONTIERS IN PLANT SCIENCE 2020; 11:416. [PMID: 32457766 PMCID: PMC7198884 DOI: 10.3389/fpls.2020.00416] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/23/2020] [Indexed: 06/11/2023]
Abstract
Floral symmetry (corolla symmetry) has important biological significance in plant genetics and evolution. However, it is often multi-dimensional and difficult to quantify. Here, we constructed a multi-dimensional data matrix [X Y Z] by extracting three qualitative variables with binary properties (X: corolla regularity of interval and coplanarity; Y: petal regularity of shape and size; Z: petal local regularity of curling and wrinkle) from different dimensions of petals (overall to individual, and then to the local): all petals (corolla), individual petals, and local areas of petals. To quantitatively express the degree of Malus corolla symmetry, these variables were then combined with weight assignments (X: 22 > Y: 21 > Z: 20) based on their contributions to the corolla symmetry and the algorithm rule of converting binary to decimal values, which facilitated the unification of qualitative and quantitative analyses. Our results revealed significant reduction in degrees of Malus corolla symmetry along the direction of local to overall. Species showed higher degree of corolla symmetry than cultivars; however, taxa with stronger corolla symmetry might not necessarily be species. These findings provide new insights into the circumscription of Malus controversial species. The matrix model should be reference for future evaluation of angiosperm flower symmetry (lack of corolla fusion).
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Affiliation(s)
- Ting Zhou
- College of Forestry, Nanjing Forestry University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
- Department of Horticulture, University of Georgia, Athens, GA, United States
| | - Wangxiang Zhang
- College of Forestry, Nanjing Forestry University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
- Yangzhou Crabapple Horticulture Company Limited, Yangzhou, China
| | - Donglin Zhang
- Department of Horticulture, University of Georgia, Athens, GA, United States
| | - Yousry A. El-Kassaby
- Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Junjun Fan
- College of Horticulture Jinling Institute of Technology, Nanjing, China
| | - Hao Jiang
- College of Forestry, Nanjing Forestry University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Guibin Wang
- College of Forestry, Nanjing Forestry University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Fuliang Cao
- College of Forestry, Nanjing Forestry University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
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12
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Ye ZM, Jin XF, Yang J, Wang QF, Yang CF. Accurate position exchange of stamen and stigma by movement in opposite direction resolves the herkogamy dilemma in a protandrous plant, Ajuga decumbens (Labiatae). AOB PLANTS 2019; 11:plz052. [PMID: 31579102 PMCID: PMC6757348 DOI: 10.1093/aobpla/plz052] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 08/13/2019] [Indexed: 06/01/2023]
Abstract
Herkogamy is an effective way to reduce sexual interference. However, the separation of stigma and anther potentially leads to a conflict because the pollen may be placed in a location on the pollinator different from the point of stigma contact, which can reduce pollination accuracy. Floral mechanisms aiming to resolve this conflict have seldom been explored. The floral biology of protandrous Ajuga decumbens was studied to uncover how the herkogamy dilemma can be resolved. Flower anthesis was divided into male, middle, female and wilting phases. The positions of stigma and stamen were dissimilar in different flower development stages. We measured the distance of the stamen and stigma to the lower corolla lip at different floral phases, which was the pollinators' approaching way. The pollen viability, stigma receptivity, pollen removal and pollen deposition on stigma were investigated at different phases. During the male phase, the dehisced anthers were lower than the stigma, located at the pollinators' approaching way, and dispersed most pollen with high viability. As the flower developed, the anthers moved upwards, making way for pollen deposition during the female phase. Meanwhile, the stigma becomes receptive by moving into the way and consequently was deposited with sufficient pollen. The position exchange of the stamen and stigma created a dynamic herkogamy at the floral phase with different sexual functions. This floral mechanism effectively avoided sexual interference and maintained pollination accuracy. In Ajuga, the movement herkogamy might be of adaptive significance in response to the changes in the pollination environment.
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Affiliation(s)
- Zhong-Ming Ye
- CAS Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
| | - Xiao-Fang Jin
- Institute of Ecology and Environmental Science, Nanchang Institute of Technology, Nanchang, China
| | - Jian Yang
- CAS Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
| | - Qing-Feng Wang
- CAS Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
| | - Chun-Feng Yang
- CAS Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
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13
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Minnaar C, Anderson B, de Jager ML, Karron JD. Plant-pollinator interactions along the pathway to paternity. ANNALS OF BOTANY 2019; 123:225-245. [PMID: 30535041 PMCID: PMC6344347 DOI: 10.1093/aob/mcy167] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 11/23/2018] [Indexed: 05/09/2023]
Abstract
Background The male fitness pathway, from pollen production to ovule fertilization, is thought to strongly influence reproductive trait evolution in animal-pollinated plants. This pathway is characterized by multiple avenues of pollen loss which may lead to reductions in male fitness. However, empirical data on the mechanistic processes leading to pollen loss during transport are limited, and we therefore lack a comprehensive understanding of how male fitness is influenced by each step in the pollination process. Scope This review assesses the history of studying male function in plants and identifies critical gaps in our understanding of the ecology and evolution of pollen transport. We explore male reproductive function along the steps of the pathway to paternity and discuss evolutionary options to overcome barriers to siring success. In particular, we present a newly emerging idea that bodies of pollinators function as a dynamic arena facilitating intense male-male competition, where pollen of rival males is constantly covered or displaced by competitors. This perspective extends the pollen-competitive arena beyond the confines of the stigma and style, and highlights the opportunity for important new breakthroughs in the study of male reproductive strategies and floral evolution.
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Affiliation(s)
- Corneile Minnaar
- Department of Botany and Zoology, Stellenbosch University, Matieland, South Africa
| | - Bruce Anderson
- Department of Botany and Zoology, Stellenbosch University, Matieland, South Africa
| | - Marinus L de Jager
- Department of Botany and Zoology, Stellenbosch University, Matieland, South Africa
| | - Jeffrey D Karron
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
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14
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Armbruster WS, Wege JA. Detecting canalization and intra-floral modularity in triggerplant (Stylidium) flowers: correlations are only part of the story. ANNALS OF BOTANY 2019; 123:355-372. [PMID: 30383191 PMCID: PMC6344225 DOI: 10.1093/aob/mcy184] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 09/18/2018] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS The Berg hypothesis proposes that specialized-flower traits experience stronger stabilizing selection than non-floral structures and predicts that variation in specialized-flower traits will be mostly uncorrelated with variation in non-floral traits. Similarly, adaptive-accuracy theory predicts lower variation (as a proportion of the mean) in floral traits than in non-floral ones. Both hypotheses can be extended to comparisons between floral traits, where different parts of the flower can be expected to experience different strengths of stabilizing selection, resulting in contrasting patterns of variation. The present study tests these ideas by analysing variation/covariation in those floral traits influencing the location of pollen placement on, and stigma contact with, pollinators ('pollination-mechanics traits', PMTs) in relation to variation/covariation in non-floral traits and floral traits not directly involved in the mechanics of pollination. The prediction was that PMTs are canalized (buffered against genetic and environmental variation) relative to attraction traits, as manifested in lower variances and modular independence. METHODS Floral and inflorescence structures of ten species of triggerplants (Stylidium, Stylidiaceae) in south-western Australia were measured; the data were analysed using multivariate and bivariate approaches to detect modular structure of floral and non-floral traits and assess evidence for canalization of PMTs. KEY RESULTS Only six of the ten species had PMTs with smaller correlation coefficients than attraction traits, in contrast to the Berg expectation. However, allometric and variance patterns were generally consistent with the predictions of an extended Berg hypothesis and adaptive accuracy. There was modular separation of most floral traits from non-floral traits and clear intra-floral modular structure. PMTs showed lower proportional variation and shallower allometric slopes than pollinator-attraction traits in nine and eight, respectively, of ten species. CONCLUSIONS This study demonstrates the value of allometric and variance analyses (in addition to correlation) in assessing the evolutionary significance of floral-trait stability and plasticity.
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Affiliation(s)
- W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth, UK
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Juliet A Wege
- Western Australian Herbarium, Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Bentley, Western Australia, Australia
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15
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Pélabon C, Tidière M, Lemaître JF, Gaillard JM. Modelling allometry: statistical and biological considerations – a reply to Packard. Biol J Linn Soc Lond 2018. [DOI: 10.1093/biolinnean/bly141] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Christophe Pélabon
- Department of Biology; Centre for Biodiversity Dynamics, NTNU, Norwegian University of Science and Technology, Trondheim, Norway
| | - Morgane Tidière
- Department of Biology; Centre for Biodiversity Dynamics, NTNU, Norwegian University of Science and Technology, Trondheim, Norway
| | - Jean-François Lemaître
- Université Lyon 1; CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, Villeurbanne, France
| | - Jean-Michel Gaillard
- Université Lyon 1; CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, Villeurbanne, France
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Spencer V, Kim M. Re“CYC”ling molecular regulators in the evolution and development of flower symmetry. Semin Cell Dev Biol 2018; 79:16-26. [DOI: 10.1016/j.semcdb.2017.08.052] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 07/28/2017] [Indexed: 11/27/2022]
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17
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Joint evolution of interspecific mutualism and regulation of variation of interaction under directional selection in trait space. THEOR ECOL-NETH 2017. [DOI: 10.1007/s12080-017-0343-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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18
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The evolvability of herkogamy: Quantifying the evolutionary potential of a composite trait. Evolution 2017; 71:1572-1586. [DOI: 10.1111/evo.13258] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/21/2017] [Indexed: 12/18/2022]
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19
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Arceo-Gómez G, Vargas CF, Parra-Tabla V. Selection on intra-individual variation in stigma-anther distance in the tropical tree Ipomoea wolcottiana (Convolvulaceae). PLANT BIOLOGY (STUTTGART, GERMANY) 2017; 19:454-459. [PMID: 28135024 DOI: 10.1111/plb.12553] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 01/25/2017] [Indexed: 06/06/2023]
Abstract
It is well known that animals can exert strong selective pressures on plant traits. However, studies on the evolutionary consequences of plant-animal interactions have mainly focused on understanding how these interactions shape trait means, while overlooking its potential direct effect on the variability among structures within a plant (e.g. flowers and fruits). The degree of within-plant variability can have strong fitness effects but few studies have evaluated its role as a potential target of selection. Here we reanalysed data on Ipomoea wolcottiana stigma-anther distance to test alternate mechanisms driving selection on the mean as well as on intra-individual variance in 2 years. We found strong negative selection acting on intra-individual variation but not on mean stigma-anther distance, suggesting independent direct selection on the latter. Our result suggests that intra-individual variance has the potential to be an important target of selection in nature, and that ignoring it could lead to the wrong characterisation of the selection regime. We highlight the need for future studies to consider patterns of selection on the mean as well as on intra-individual variance if we want to understand the full extent of plant-animal interactions as an evolutionary force in nature.
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Affiliation(s)
- G Arceo-Gómez
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN, USA
| | - C F Vargas
- Laboratorio de Variación Biológica y Evolución, Escuela Nacional de Ciencias Biológicas-Instituto Politécnico Nacional, México, México
| | - V Parra-Tabla
- Departamento de Ecología Tropical, Universidad Autónoma de Yucatán, Mérida, México
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20
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O'Meara BC, Smith SD, Armbruster WS, Harder LD, Hardy CR, Hileman LC, Hufford L, Litt A, Magallón S, Smith SA, Stevens PF, Fenster CB, Diggle PK. Non-equilibrium dynamics and floral trait interactions shape extant angiosperm diversity. Proc Biol Sci 2016; 283:20152304. [PMID: 27147092 PMCID: PMC4874697 DOI: 10.1098/rspb.2015.2304] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 04/08/2016] [Indexed: 12/28/2022] Open
Abstract
Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we examine the role of transition rates, differential diversification (speciation minus extinction) and non-equilibrium dynamics on the evolutionary history of angiosperms, a clade well known for the abundance of some trait combinations and the rarity of others. Our analysis reveals that three character states (corolla present, bilateral symmetry, reduced stamen number) act synergistically as a key innovation, doubling diversification rates for lineages in which this combination occurs. However, this combination is currently less common than predicted at equilibrium because the individual characters evolve infrequently. Simulations suggest that angiosperms will remain far from the equilibrium frequencies of character states well into the future. Such non-equilibrium dynamics may be common when major innovations evolve rarely, allowing lineages with ancestral forms to persist, and even outnumber those with diversification-enhancing states, for tens of millions of years.
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Affiliation(s)
- Brian C O'Meara
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Stacey D Smith
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA
| | - W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Lawrence D Harder
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | | | - Lena C Hileman
- Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA
| | - Larry Hufford
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - Amy Litt
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA The New York Botanical Garden, Bronx, NY 10459, USA
| | - Susana Magallón
- Instituto de Biología, Universidad Nacional Autónoma de México, México DF 04510, México
| | - Stephen A Smith
- Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Charles B Fenster
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA
| | - Pamela K Diggle
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269-3043, USA
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21
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Endress PK. Development and evolution of extreme synorganization in angiosperm flowers and diversity: a comparison of Apocynaceae and Orchidaceae. ANNALS OF BOTANY 2016; 117:749-67. [PMID: 26292994 PMCID: PMC4845794 DOI: 10.1093/aob/mcv119] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 06/22/2015] [Indexed: 05/04/2023]
Abstract
BACKGROUND AND AIMS Apocynaceae and Orchidaceae are two angiosperm families with extreme flower synorganization. They are unrelated, the former in eudicots, the latter in monocots, but they converge in the formation of pollinia and pollinaria, which do not occur in any other angiosperm family, and for which extreme synorganization of floral organs is a precondition. In each family extensive studies on flower development and evolution have been performed; however, newer comparative studies focusing on flower synorganization and involving both families together are lacking. SCOPE For this study an extensive search through the morphological literature has been conducted. Based on this and my own studies on flowers in various Apocynaceae and Orchidaceae and complex flowers in other angiosperms with scanning electron microscopy and with microtome section series, a review on convergent floral traits in flower development and architecture in the two families is presented. KEY FINDINGS There is a tendency of protracted development of synorganized parts in Apocynaceae and Orchidaceae (development of synorganization of two or more organs begins earlier the more accentuated it is at anthesis). Synorganization (or complexity) also paves the way for novel structures. One of the most conspicuous such novel structures in Apocynaceae is the corona, which is not the product of synorganization of existing organs; however, it is probably enhanced by synorganization of other, existing, floral parts. In contrast to synorganized parts, the corona appears developmentally late. CONCLUSIONS Synorganization of floral organs may lead to a large number of convergences in clades that are only very distantly related. The convergences that have been highlighted in this comparative study should be developmentally investigated directly in parallel in future studies.
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Affiliation(s)
- Peter K Endress
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland
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22
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Gómez JM, Torices R, Lorite J, Klingenberg CP, Perfectti F. The role of pollinators in the evolution of corolla shape variation, disparity and integration in a highly diversified plant family with a conserved floral bauplan. ANNALS OF BOTANY 2016; 117:889-904. [PMID: 26884512 PMCID: PMC4845802 DOI: 10.1093/aob/mcv194] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Revised: 09/17/2015] [Accepted: 10/14/2015] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Brassicaceae is one of the most diversified families in the angiosperms. However, most species from this family exhibit a very similar floral bauplan. In this study, we explore the Brassicaceae floral morphospace, examining how corolla shape variation (an estimation of developmental robustness), integration and disparity vary among phylogenetically related species. Our aim is to check whether these floral attributes have evolved in this family despite its apparent morphological conservation, and to test the role of pollinators in driving this evolution. METHODS Using geometric morphometric tools, we calculated the phenotypic variation, disparity and integration of the corolla shape of 111 Brassicaceae taxa. We subsequently inferred the phylogenetic relationships of these taxa and explored the evolutionary lability of corolla shape. Finally, we sampled the pollinator assemblages of every taxon included in this study, and determined their pollination niches using a modularity algorithm. We explore the relationship between pollination niche and the attributes of corolla shape. KEY RESULTS Phylogenetic signal was weak for all corolla shape attributes. All taxa had generalized pollination systems. Nevertheless, they belong to different pollination niches. There were significant differences in corolla shape among pollination niches even after controlling for the phylogenetic relationship of the plant taxa. Corolla shape variation and disparity was significantly higher in those taxa visited mostly by nocturnal moths, indicating that this pollination niche is associated with a lack of developmental robustness. Corolla integration was higher in those taxa visited mostly by hovering long-tongued flies and long-tongued large bees. CONCLUSIONS Corolla variation, integration and disparity were evolutionarily labile and evolved very recently in the evolutionary history of the Brassicaceae. These floral attributes were strongly related to the pollination niche. Even in a plant clade having a very generalized pollination system and exhibiting a conserved floral bauplan, pollinators can drive the evolution of important developmental attributes of corolla shape.
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Affiliation(s)
- José M Gómez
- Department of Functional and Evolutionary Ecology, Estación Experimental de Zonas Áridas (EEZA-CSIC), Almería, Spain, Department of Ecology,
| | - Ruben Torices
- Department of Functional and Evolutionary Ecology, Estación Experimental de Zonas Áridas (EEZA-CSIC), Almería, Spain, Centre for Functional Ecology, Department of Life Science, University of Coimbra, Coimbra, Portugal and
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23
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Pélabon C, Hennet L, Bolstad GH, Albertsen E, Opedal ØH, Ekrem RK, Armbruster WS. Does stronger pollen competition improve offspring fitness when pollen load does not vary? AMERICAN JOURNAL OF BOTANY 2016; 103:522-531. [PMID: 26451034 DOI: 10.3732/ajb.1500126] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 05/22/2015] [Indexed: 06/05/2023]
Abstract
PREMISE OF THE STUDY Competition among pollen grains from a single donor is expected to increase the quality of the offspring produced because of the recessive deleterious alleles expressed during pollen-tube growth. However, evidence for such an effect is inconclusive; a large number of studies suffer from confounding variation in pollen competition with variation in pollen load. METHODS In this study, we tested the effect of pollen competition on offspring performance independently of pollen-load variation. We compared seed mass and early seedling performance in Dalechampia scandens (Euphorbiaceae) between crosses in which variation in pollen competition was achieved, without variation in pollen load, by manipulating the dispersion of pollen grains on the stigmas. KEY RESULTS Despite a large sample size (211 crosses on 20 maternal plants), we failed to find an effect of pollen competition on seed characteristics or early seedling performance. Paternal effects were always limited, and pollen competition never reduced the within-father (residual) variance. CONCLUSION These results suggest that limited within-donor variation in genetic quality of pollen grains reduces the potential benefits of pollen competition in the study population. The lack of paternal effects on early sporophyte performance further suggests that benefits of pollen competition among pollen from multiple donors should be limited as well, and it raises questions about the significance of pollen competition as a mechanism of sexual selection.
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Affiliation(s)
- Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Lauriane Hennet
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Geir H Bolstad
- Norwegian Institute for Nature Research, 7485 Trondheim, Norway
| | - Elena Albertsen
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Øystein H Opedal
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Runa K Ekrem
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - W Scott Armbruster
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway School of Biological Sciences, King Henry Building, King Henry I Street, University of Portsmouth, Portsmouth PO1 2DY, UK Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775 USA
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24
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Fornoni J, Ordano M, Pérez-Ishiwara R, Boege K, Domínguez CA. A comparison of floral integration between selfing and outcrossing species: a meta-analysis. ANNALS OF BOTANY 2016; 117:299-306. [PMID: 26578721 PMCID: PMC4724042 DOI: 10.1093/aob/mcv166] [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: 08/26/2015] [Revised: 09/10/2015] [Accepted: 09/16/2015] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Floral integration is thought to be an adaptation to promote cross-fertilization, and it is often assumed that it increases morphological matching between flowers and pollinators, increasing the efficiency of pollen transfer. However, the evidence for this role of floral integration is limited, and recent studies have suggested a possible positive association between floral integration and selfing. Although a number of explanations exist to account for this inconsistency, to date there has been no attempt to examine the existence of an association between floral integration and mating system. This study hypothesized that if pollinator-mediated pollen movement among plants (outcrossing) is the main factor promoting floral integration, species with a predominantly outcrossing mating system should present higher levels of floral integration than those with a predominantly selfing mating system. METHODS A phylogenetically informed meta-analysis of published data was performed in order to evaluate whether mating system (outcrossing vs. selfing) accounts for the variation in floral integration among 64 species of flowering plants. Morphometric floral information was used to compare intra-floral integration among traits describing sexual organs (androecium and gynoecium) and those corresponding to the perianth (calix and corolla). KEY RESULTS The analysis showed that outcrossing species have lower floral integration than selfing species. This pattern was caused by significantly higher integration of sexual traits than perianth traits, as integration of the latter group remained unchanged across mating categories. CONCLUSIONS The results suggest that the evolution of selfing is associated with concomitant changes in intra-floral integration. Thus, floral integration of sexual traits should be considered as a critical component of the selfing syndrome.
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Affiliation(s)
- Juan Fornoni
- Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, Ciudad Universitaria 04510, México Distrito Federal, México and
| | - Mariano Ordano
- Fundación Miguel Lillo, Miguel Lillo 251, San Miguel de Tucumán T4000JFE, Tucumán, Argentina, and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Rubén Pérez-Ishiwara
- Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, Ciudad Universitaria 04510, México Distrito Federal, México and
| | - Karina Boege
- Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, Ciudad Universitaria 04510, México Distrito Federal, México and
| | - César A Domínguez
- Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, Ciudad Universitaria 04510, México Distrito Federal, México and
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25
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Opedal ØH, Armbruster WS, Pélabon C. Inbreeding effects in a mixed-mating vine: effects of mating history, pollen competition and stress on the cost of inbreeding. AOB PLANTS 2015; 7:plv133. [PMID: 26578744 PMCID: PMC4683981 DOI: 10.1093/aobpla/plv133] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 11/07/2015] [Indexed: 06/01/2023]
Abstract
Inbreeding depression is assumed to be a central factor contributing to the stability of plant mating systems. Predicting the fitness consequence of inbreeding in natural populations is complicated, however, because it may be affected by the mating histories of populations generating variation in the amount of purging of deleterious alleles. Furthermore, the level of inbreeding depression may depend on environmental conditions and the intensity of pollen competition. In a greenhouse experiment comparing four populations of the neotropical vine Dalechampia scandens (Euphorbiaceae), we tested whether inbreeding depression for early-life fitness depended on the inferred mating history of each population, as indicated by genetically determined differences in herkogamy and autofertility rates. We also tested whether the intensity of pollen competition and the level of stress encountered by the seeds and seedlings affected the amount of inbreeding depression observed. Herkogamy was a good predictor of autofertility in each population. However, we found only limited evidence for inbreeding depression in any population, and inbreeding depression varied independently of the intensity of pollen competition and amount of stress encountered by the seeds and seedlings. Thus, the population's rate of autofertility did not predict the amount of inbreeding depression. Overall, we found no evidence supporting the expectations that more inbred populations experience less inbreeding depression, and that pollen competition reduces the cost of inbreeding. These results suggest that additional factors may be responsible for the maintenance of the mixed mating systems of D. scandens populations.
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Affiliation(s)
- Øystein H Opedal
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - W Scott Armbruster
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway School of Biological Sciences, University of Portsmouth, King Henry Building, King Henry I Street, Portsmouth PO1 2DY, UK Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA
| | - Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
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26
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Pérez-Barrales R, Simón-Porcar VI, Santos-Gally R, Arroyo J. Phenotypic integration in style dimorphic daffodils (Narcissus, Amaryllidaceae) with different pollinators. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130258. [PMID: 25002703 PMCID: PMC4084543 DOI: 10.1098/rstb.2013.0258] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Different pollinators can exert different selective pressures on floral traits, depending on how they fit with flowers, which should be reflected in the patterns of variation and covariation of traits. Surprisingly, empirical evidence in support of this view is scarce. Here, we have studied whether the variation observed in floral phenotypic integration and covariation of traits in Narcissus species is associated with different groups of pollinators. Phenotypic integration was studied in two style dimorphic species, both with dimorphic populations mostly visited by long-tongued pollinators (close fit with flowers), and monomorphic populations visited by short-tongued insects (loose fit). For N. papyraceus, the patterns of variation and correlation among traits involved in different functions (attraction and fit with pollinators, transfer of pollen) were compared within and between population types. The genetic diversity of populations was also studied to control for possible effects on phenotypic variation. In both species, populations with long-tongued pollinators displayed greater phenotypic integration than those with short-tongued pollinators. Also, the correlations among traits involved in the same function were stronger than across functions. Furthermore, traits involved in the transfer of pollen were consistently more correlated and less variable than traits involved in the attraction of insects, and these differences were larger in dimorphic than monomorphic populations. In addition, population genetic parameters did not correlate with phenotypic integration or variation. Altogether, our results support current views of the role of pollinators in the evolution of floral integration.
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Affiliation(s)
- Rocío Pérez-Barrales
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK Departmento de Biología Vegetal y Ecología, University of Seville, Seville 41080, Spain
| | | | - Rocío Santos-Gally
- Departmento de Biología Vegetal y Ecología, University of Seville, Seville 41080, Spain
| | - Juan Arroyo
- Departmento de Biología Vegetal y Ecología, University of Seville, Seville 41080, Spain
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Armbruster WS, Pélabon C, Bolstad GH, Hansen TF. Integrated phenotypes: understanding trait covariation in plants and animals. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130245. [PMID: 25002693 PMCID: PMC4084533 DOI: 10.1098/rstb.2013.0245] [Citation(s) in RCA: 169] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Integration and modularity refer to the patterns and processes of trait interaction and independence. Both terms have complex histories with respect to both conceptualization and quantification, resulting in a plethora of integration indices in use. We review briefly the divergent definitions, uses and measures of integration and modularity and make conceptual links to allometry. We also discuss how integration and modularity might evolve. Although integration is generally thought to be generated and maintained by correlational selection, theoretical considerations suggest the relationship is not straightforward. We caution here against uncontrolled comparisons of indices across studies. In the absence of controls for trait number, dimensionality, homology, development and function, it is difficult, or even impossible, to compare integration indices across organisms or traits. We suggest that care be invested in relating measurement to underlying theory or hypotheses, and that summative, theory-free descriptors of integration generally be avoided. The papers that follow in this Theme Issue illustrate the diversity of approaches to studying integration and modularity, highlighting strengths and pitfalls that await researchers investigating integration in plants and animals.
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Affiliation(s)
- W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth PO12DY, UK Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Christophe Pélabon
- Center for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Geir H Bolstad
- Center for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Thomas F Hansen
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, PO Box 1066, 0316 Oslo, Norway
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28
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Pélabon C, Firmat C, Bolstad GH, Voje KL, Houle D, Cassara J, Rouzic AL, Hansen TF. Evolution of morphological allometry. Ann N Y Acad Sci 2014; 1320:58-75. [DOI: 10.1111/nyas.12470] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christophe Pélabon
- Department of Biology; Centre for Biodiversity Dynamics; Norwegian University of Science and Technology; Trondheim Norway
| | - Cyril Firmat
- Department of Biology; Centre for Biodiversity Dynamics; Norwegian University of Science and Technology; Trondheim Norway
| | - Geir H. Bolstad
- Department of Biology; Centre for Biodiversity Dynamics; Norwegian University of Science and Technology; Trondheim Norway
| | - Kjetil L. Voje
- Department of Biology; Centre for Ecological and Evolutionary Synthesis; University of Oslo; Oslo Norway
| | - David Houle
- Department of Biological Science; Florida State University; Tallahassee Florida
| | - Jason Cassara
- Department of Biological Science; Florida State University; Tallahassee Florida
| | - Arnaud Le Rouzic
- Laboratoire Evolution, Génomes, Spéciation; Centre National de la Recherche Scientifique; Gif-sur-Yvette France
| | - Thomas F. Hansen
- Department of Biology; Centre for Ecological and Evolutionary Synthesis; University of Oslo; Oslo Norway
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29
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Armbruster WS, Corbet SA, Vey AJM, Liu SJ, Huang SQ. In the right place at the right time: Parnassia resolves the herkogamy dilemma by accurate repositioning of stamens and stigmas. ANNALS OF BOTANY 2014; 113:97-103. [PMID: 24265349 PMCID: PMC3864732 DOI: 10.1093/aob/mct261] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND AIMS Spatial (herkogamy) and temporal (dichogamy) separation of pollen presentation and stigma receptivity have been interpreted as reducing interference between male and female functions in hermaphroditic flowers. However, spatial separation leads to a potential conflict: reduced pollination accuracy, where pollen may be placed in a location on the pollinator different from the point of stigma contact. METHODS To understand better how herkogamous flowers resolve this conflict, a study was made of a subalpine herb, Parnassia epunctulata, the nectariferous flowers of which exhibit sequential anther dehiscence (staggered pollen presentation) and stamen movements; usually one newly dehisced anther is positioned each day over the central gynoecium, while the older stamens bend away from the central position. KEY RESULTS The open flowers were visited by a variety of pollinators, most of which were flies. Seed set was pollinator-dependent (bagged flowers set almost no seeds) and pollen-limited (manual pollination increased seed set over open pollination). Analyses of adaptive accuracy showed that coordinated stamen movements and style elongation (movement herkogamy) dramatically increased pollination accuracy. Specifically, dehiscing anthers and receptive stigmas were positioned accurately in the vertical and horizontal planes in relation to the opposite sexual structure and pollinator position. By contrast, the spatial correspondence between anthers and stigma was dramatically lower before the anthers dehisced and after stamens bent outwards, as well as before and after the period of stigmatic receptivity. CONCLUSIONS It is shown for the first time that a combination of movement herkogamy and dichogamy can maintain high pollination accuracy in flowers with generalized pollination. Staggered pollen and stigma presentation with spatial correspondence can both reduce sexual interference and improve pollination accuracy.
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Affiliation(s)
- W. Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
- Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775-7000, USA
- Department of Biology, NTNU, N-7491 Trondheim, Norway
| | - Sarah A. Corbet
- 1 St Loy Cottages, St Buryan, Penzance, Cornwall TR19 6DH, UK
| | - Aidan J. M. Vey
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
| | - Shu-Juan Liu
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Shuang-Quan Huang
- College of Life Sciences, Central China Normal University, Wuhan 430079, China
- For correspondence. E-mail
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Huang SQ, Shi XQ. Floral isolation in Pedicularis: how do congeners with shared pollinators minimize reproductive interference? THE NEW PHYTOLOGIST 2013; 199:858-65. [PMID: 23672259 DOI: 10.1111/nph.12327] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 04/14/2013] [Indexed: 05/23/2023]
Abstract
To minimize interspecific pollination, it has been suggested that pollen is placed on different parts of a pollinator's body corresponding to the conspecific location of pollen pickup by the stigma. Although Pedicularis is regarded as a classic example of pollinator-mediated floral isolation, such reciprocal pollen placement has not been demonstrated experimentally. This leads us to question previous observations of pollen release in Pedicularis species. Here, we show that pollen grains are released from the tip, rather than the basal opening, of the galea (the hoodlike upper lip of the corolla) in eight nectarless Pedicularis species, mimicking pollen release from poricidal anthers. We used safranin-stained pollen within anthers to track pollen placement in three Pedicularis species, and showed that pollen was deposited on numerous parts of the bumblebee's body. However, fluorescent powder placed on the stigmas to detect the contact location on the bumblebee's body was deposited mainly on the major position of pollen placement in each of the three species. Such segregation of pollen placement and pickup between species sharing the same pollinator probably helps to reduce reproductive interference, but the positions of pollen placement and stigma contact on the bumblebee's body were not as precise as previously thought.
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Affiliation(s)
- Shuang-Quan Huang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China.
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Pérez-Barrales R, Bolstad GH, Pélabon C, Hansen TF, Armbruster WS. Pollinators and seed predators generate conflicting selection onDalechampiablossoms. OIKOS 2013. [DOI: 10.1111/j.1600-0706.2013.20780.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Exploring power and parameter estimation of the BiSSE method for analyzing species diversification. BMC Evol Biol 2013; 13:38. [PMID: 23398853 PMCID: PMC3583807 DOI: 10.1186/1471-2148-13-38] [Citation(s) in RCA: 177] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 01/24/2013] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND There has been a considerable increase in studies investigating rates of diversification and character evolution, with one of the promising techniques being the BiSSE method (binary state speciation and extinction). This study uses simulations under a variety of different sample sizes (number of tips) and asymmetries of rate (speciation, extinction, character change) to determine BiSSE's ability to test hypotheses, and investigate whether the method is susceptible to confounding effects. RESULTS We found that the power of the BiSSE method is severely affected by both sample size and high tip ratio bias (one character state dominates among observed tips). Sample size and high tip ratio bias also reduced accuracy and precision of parameter estimation, and resulted in the inability to infer which rate asymmetry caused the excess of a character state. In low tip ratio bias scenarios with appropriate tip sample size, BiSSE accurately estimated the rate asymmetry causing character state excess, avoiding the issue of confounding effects. CONCLUSIONS Based on our findings, we recommend that future studies utilizing BiSSE that have fewer than 300 terminals and/or have datasets where high tip ratio bias is observed (i.e., fewer than 10% of species are of one character state) should be extremely cautious with the interpretation of hypothesis testing results.
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Boucher FC, Thuiller W, Arnoldi C, Albert CH, Lavergne S. Unravelling the architecture of functional variability in wild populations of Polygonum viviparum L. Funct Ecol 2013; 27:382-391. [PMID: 24790285 DOI: 10.1111/1365-2435.12034] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Functional variability (FV) of populations can be decomposed into three main features: the individual variability of multiple traits, the strength of correlations between those traits and the main direction of these correlations, the latter two being known as 'phenotypic integration'. Evolutionary biology has long recognized that FV in natural populations is key to determining potential evolutionary responses, but this topic has been little studied in functional ecology.Here we focus on the arctico-alpine perennial plant species Polygonum viviparum L.. We used a comprehensive sampling of seven functional traits in 29 wild populations covering the whole environmental niche of the species. The niche of the species was captured by a temperature gradient, which separated alpine stressful habitats from species-rich, competitive sub-alpine ones. We seeked to assess the relative roles of abiotic stress and biotic interactions in shaping different aspects of functional variation within and among populations, that is, the multi-trait variability, the strength of correlations between traits, and the main directions of functional trade-offs.Populations with the highest extent of functional variability were found in the warm end of the gradient whereas populations exhibiting the strongest degree of phenotypic integration were located in sites with intermediate temperatures. This could reveal both the importance of environmental filtering and population demography in structuring FV. Interestingly, we found that the main axes of multivariate functional variation were radically different within and across population.Although the proximate causes of FV structure remain uncertain, our study presents a robust methodology for the quantitative study of functional variability in connection with species' niches. It also opens up new perspectives for the conceptual merging of intraspecific functional patterns with community ecology.
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Affiliation(s)
- Florian C Boucher
- Laboratoire d'Ecologie Alpine, UMR 5533 CNRS-Université de Grenoble, Grenoble, France
| | - Wilfried Thuiller
- Laboratoire d'Ecologie Alpine, UMR 5533 CNRS-Université de Grenoble, Grenoble, France
| | - Cindy Arnoldi
- Laboratoire d'Ecologie Alpine, UMR 5533 CNRS-Université de Grenoble, Grenoble, France
| | - Cécile H Albert
- Laboratoire d'Ecologie Alpine, UMR 5533 CNRS-Université de Grenoble, Grenoble, France ; Department of Biology, McGill University, Montréal, Canada
| | - Sébastien Lavergne
- Laboratoire d'Ecologie Alpine, UMR 5533 CNRS-Université de Grenoble, Grenoble, France
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Bartoszek K, Pienaar J, Mostad P, Andersson S, Hansen TF. A phylogenetic comparative method for studying multivariate adaptation. J Theor Biol 2012; 314:204-15. [DOI: 10.1016/j.jtbi.2012.08.005] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Revised: 06/18/2012] [Accepted: 08/03/2012] [Indexed: 11/27/2022]
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Armbruster WS, Gong YB, Huang SQ. Are Pollination “Syndromes” Predictive? Asian Dalechampia Fit Neotropical Models. Am Nat 2011; 178:135-43. [DOI: 10.1086/660279] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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ALCANTARA SUZANA, LOHMANN LÚCIAG. Contrasting phylogenetic signals and evolutionary rates in floral traits of Neotropical lianas. Biol J Linn Soc Lond 2011. [DOI: 10.1111/j.1095-8312.2010.01567.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Woodward FI. Flower power. THE NEW PHYTOLOGIST 2010; 188:639-640. [PMID: 20955414 DOI: 10.1111/j.1469-8137.2010.03487.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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Pélabon C, Armbruster WS, Hansen TF. Experimental evidence for the Berg hypothesis: vegetative traits are more sensitive than pollination traits to environmental variation. Funct Ecol 2010. [DOI: 10.1111/j.1365-2435.2010.01770.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Christophe Pélabon
- Department of Biology, Centre for Conservation Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - W. Scott Armbruster
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
- School of Biological Sciences, King Henry Building, University of Portsmouth, Portsmouth PO1 2DY, UK
- Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775, USA
| | - Thomas F. Hansen
- Department of Biology, Centre for Ecological and Evolutionary Synthesis, University of Oslo, 0316 Oslo, Norway
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Armbruster WS, Lee J, Baldwin BG. Macroevolutionary patterns of defense and pollination in Dalechampia vines: adaptation, exaptation, and evolutionary novelty. Proc Natl Acad Sci U S A 2009; 106:18085-90. [PMID: 19841278 PMCID: PMC2775306 DOI: 10.1073/pnas.0907051106] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Indexed: 11/18/2022] Open
Abstract
We conducted phylogenetically informed comparative analyses of 81 taxa of Dalechampia (Euphorbiaceae) vines and shrubs to assess the roles of historical contingency and trait interaction in the evolution of plant-defense and pollinator-attraction systems. We asked whether defenses can originate by exaptation from preexisting pollinator attractants, or vice versa, whether plant defenses show escalation, and if so, whether by enhancing one line of defense or by adding new lines of defense. Two major patterns emerged: (i) correlated evolution of several complementary lines of defense of flowers, seeds, and leaves, and (ii) 5 to 6 losses of the resin reward, followed by redeployment of resin for defense of male flowers in 3 to 4 lineages, apparently in response to herbivore-mediated selection for defense of staminate flowers upon relaxation of pollinator-mediated selection on resin. In all cases, redeployment of resin involved reversion to the inferred ancestral arrangement of flowers and resiniferous bractlets. Triterpene resin has also been deployed for defense of leaves and developing seeds. Other unique defenses against florivores include nocturnal closure of large involucral bracts around receptive flowers and permanent closure around developing fruits (until opening again upon dehiscence). Escalation in one major clade occurred through an early dramatic increase in the number of lines of defense and in the other major clade by more limited increases throughout the group's evolution. We conclude that preaptations played important roles in the evolution of unique defense and attraction systems, and that the evolution of interactions with herbivores can be influenced by adaptations for pollination, and vice versa.
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Affiliation(s)
- W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom.
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