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Hederström V, Ekroos J, Friberg M, Krausl T, Opedal ØH, Persson AS, Petrén H, Quan Y, Smith HG, Clough Y. Pollinator-mediated effects of landscape-scale land use on grassland plant community composition and ecosystem functioning - seven hypotheses. Biol Rev Camb Philos Soc 2024; 99:675-698. [PMID: 38118437 DOI: 10.1111/brv.13040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/05/2023] [Accepted: 12/07/2023] [Indexed: 12/22/2023]
Abstract
Environmental change is disrupting mutualisms between organisms worldwide. Reported declines in insect populations and changes in pollinator community compositions in response to land use and other environmental drivers have put the spotlight on the need to conserve pollinators. While this is often motivated by their role in supporting crop yields, the role of pollinators for reproduction and resulting taxonomic and functional assembly in wild plant communities has received less attention. Recent findings suggest that observed and experimental gradients in pollinator availability can affect plant community composition, but we know little about when such shifts are to be expected, or the impact they have on ecosystem functioning. Correlations between plant traits related to pollination and plant traits related to other important ecosystem functions, such as productivity, nitrogen uptake or palatability to herbivores, lead us to expect non-random shifts in ecosystem functioning in response to changes in pollinator communities. At the same time, ecological and evolutionary processes may counteract these effects of pollinator declines, limiting changes in plant community composition, and in ecosystem functioning. Despite calls to investigate community- and ecosystem-level impacts of reduced pollination, the study of pollinator effects on plants has largely been confined to impacts on plant individuals or single-species populations. With this review we aim to break new ground by bringing together aspects of landscape ecology, ecological and evolutionary plant-insect interactions, and biodiversity-ecosystem functioning research, to generate new ideas and hypotheses about the ecosystem-level consequences of pollinator declines in response to land-use change, using grasslands as a focal system. Based on an integrated set of seven hypotheses, we call for more research investigating the putative pollinator-mediated links between landscape-scale land use and ecosystem functioning. In particular, future research should use combinations of experimental and observational approaches to assess the effects of changes in pollinator communities over multiple years and across species on plant communities and on trait distributions both within and among species.
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Affiliation(s)
- Veronica Hederström
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Johan Ekroos
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Magne Friberg
- Department of Biology, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Theresia Krausl
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Øystein H Opedal
- Department of Biology, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Anna S Persson
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Hampus Petrén
- Department of Biology, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Yuanyuan Quan
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Henrik G Smith
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
- Department of Biology, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
| | - Yann Clough
- Centre for Environmental and Climate Science, Lund University, Sölvegatan 37, Lund, 223 62, Sweden
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Spigler RB, Maguiña R. Changes in female function and autonomous selfing across floral lifespan interact to drive variation in the cost of selfing. AMERICAN JOURNAL OF BOTANY 2022; 109:616-627. [PMID: 35075632 PMCID: PMC9315013 DOI: 10.1002/ajb2.1816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 12/29/2021] [Accepted: 12/30/2021] [Indexed: 06/14/2023]
Abstract
PREMISE Morphological and developmental changes as flowers age can impact patterns of mating. At the same time, direct or indirect costs of floral longevity can alter their fitness outcomes. This influence has been less appreciated, particularly with respect to the timing of selfing. We investigated changes in stigma events, autonomous selfing, outcross seed set capacity, and autofertility-a measure representing the potential for reproductive assurance-across floral lifespan in the mixed-mating biennial Sabatia angularis. METHODS We examined stigma morphology and receptivity, autonomous self-pollen deposition, and seed number and size under autonomous self-pollination and hand outcross-pollination for flowers of different ages, from 1 d of female phase until 14 d. We compared autonomous seed production to maximal outcross seed production at each flower age to calculate an index of autofertility. RESULTS The stigmatic lobes begin to untwist 1 d post anthesis. They progressively open, sextend, coil, and increase in receptivity, peaking or saturating at 8-11 d, depending on the measure. Autonomous seed production can occur early, but on average remains low until 6 d, when it doubles. In contrast, outcross seed number and size start out high, then decline precipitously. Consequently, autofertility increases steeply across floral lifespan. CONCLUSIONS Changes in stigma morphology and receptivity, timing of autonomous self-pollen deposition, and floral senescence can interact to influence the relative benefit of autonomous selfing across floral lifespan. Our work highlights the interplay between evolution of floral longevity and the mating system, with implications for the maintenance of mixed mating in S. angularis.
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Affiliation(s)
- Rachel B. Spigler
- Department of BiologyTemple University1900 N 12th St.PhiladelphiaPA19122USA
| | - Rossana Maguiña
- Department of BiologyTemple University1900 N 12th St.PhiladelphiaPA19122USA
- Present address:
Rossana Maguiña, Ecology and Evolutionary Biology DepartmentUniversity of California Santa Cruz130 McAllister WaySanta CruzCA95060USA
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Tian H, Harder LD, Wang A, Zhang D, Liao W. Habitat effects on reproductive phenotype, pollinator behavior, fecundity, and mating outcomes of a bumble bee-pollinated herb. AMERICAN JOURNAL OF BOTANY 2022; 109:470-485. [PMID: 35244204 PMCID: PMC9314043 DOI: 10.1002/ajb2.1826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 06/14/2023]
Abstract
PREMISE Fecundity and mating outcomes commonly differ among plant populations occupying contrasting environments. If self-pollination occurs primarily among flowers within plants, contrasting reproductive outcomes among populations must reflect environmental effects on plant-pollinator interactions. Specifically, local conditions could affect features of plant phenotypes that influence pollinator behavior, in turn modifying plant reproductive outcomes. METHODS We compared phenotypes, pollinator abundance and behavior, and female fecundity and mating in two meadow populations and two forest populations of Aconitum kusnezoffii within 3 km of each other. Mating outcomes were assessed using microsatellites. RESULTS Meadow plants generally produced more, shorter ramets with more, larger flowers, but less nectar per flower than forest plants. These differences likely largely represent phenotypic plasticity. Individual bumble bees visited more flowers on forest plants, likely because the more abundant bees in the meadows depleted nectar availability, as indicated by briefer visits to individual flowers. Despite similar fruit set in both habitats, forest plants set more seeds per fruit. Nevertheless, meadow plants produced more seeds overall, owing to sevenfold greater flower production. Consistent with individual bees visiting fewer flowers on meadow plants, more of their seeds were outcrossed. However, the outcrossed seeds of forest plants included more male mates. CONCLUSIONS Reproductive outcomes can vary among populations of animal-pollinated plants as a result of differences in the availability of effective pollinators and environmental effects on plant phenotypes, and their functional consequences for pollinator behavior that governs pollen dispersal.
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Affiliation(s)
- Hao Tian
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Ministry of Education Key Laboratory for Biodiversity Science and Ecological EngineeringBeijing Normal UniversityBeijing100875China
| | - Lawrence D. Harder
- Department of Biological SciencesUniversity of CalgaryCalgaryAlbertaT2N 1N4Canada
| | - Ai‐Ying Wang
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Ministry of Education Key Laboratory for Biodiversity Science and Ecological EngineeringBeijing Normal UniversityBeijing100875China
| | - Da‐Yong Zhang
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Ministry of Education Key Laboratory for Biodiversity Science and Ecological EngineeringBeijing Normal UniversityBeijing100875China
| | - Wan‐Jin Liao
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Ministry of Education Key Laboratory for Biodiversity Science and Ecological EngineeringBeijing Normal UniversityBeijing100875China
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Aonuma W, Kawamoto H, Kazama Y, Ishii K, Abe T, Kawano S. Male/Female Trade-Off in Hermaphroditic Y-Chromosome Deletion Mutants of the Dioecious Plant Silene latifolia. CYTOLOGIA 2021. [DOI: 10.1508/cytologia.86.329] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Wataru Aonuma
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo
| | - Hiroki Kawamoto
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo
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Delgado-Dávila R, Martén-Rodríguez S. A test of the reproductive assurance hypothesis in Ipomoea hederacea: does inbreeding depression counteract the benefits of self-pollination? AMERICAN JOURNAL OF BOTANY 2021; 108:2162-2173. [PMID: 34786691 DOI: 10.1002/ajb2.1794] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 07/15/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
PREMISE Darwin proposed that self-pollination in allegedly outcrossing species might act as a reproductive assurance mechanism when pollinators or mates are scarce; however, in natural populations, the benefits of selfing may be opposed by seed discounting and inbreeding depression. While empirical studies show variation among species and populations in the magnitude of reproductive assurance, little is known about the counterbalancing effects of inbreeding depression. METHODS By comparing the female reproductive success of emasculated and open-pollinated flowers, we assessed the reproductive assurance hypothesis in two Mexican populations of Ipomoea hederacea. In one population, we assessed temporal variation in reproductive assurance for three years. We evaluated inbreeding depression on seed production, seedling germination, and dry plant mass by contrasting self- and cross-hand pollination treatments in one population for two years. RESULT The contribution of self-pollination to female reproductive success was high and consistent between populations, but there was variation in reproductive assurance across years. Inbreeding depression was absent in the early stages of progeny development, but there was a small negative effect of inbreeding in the probability of germination and the mass of adult progeny. CONCLUSIONS Self-pollination provided significant reproductive assurance in I. hederacea but this contribution was variable across time. The contribution of reproductive assurance is probably reduced by inbreeding depression in later stages of progeny development, but this counter effect was small in the study populations. This study supports the hypothesis that reproductive assurance with limited inbreeding depression is likely an important selective force in the evolution of self-pollination in the genus Ipomoea.
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Affiliation(s)
- Ruth Delgado-Dávila
- Universitat Autònoma de Barcelona, Cerdanyola del Vallès, 08193, Spain
- Laboratorio Nacional de Análisis y Síntesis Ecológica, Escuela Nacional de Estudios Superiores, unidad Morelia, Universidad Nacional Autónoma de México, 58089, Morelia, Michoacán, México
| | - Silvana Martén-Rodríguez
- Laboratorio Nacional de Análisis y Síntesis Ecológica, Escuela Nacional de Estudios Superiores, unidad Morelia, Universidad Nacional Autónoma de México, 58089, Morelia, Michoacán, México
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Xiao HW, Huang YB, Chang YH, Chen Y, Abbott RJ, Wei YK, Ma YP. Occurrence and Prevention of Delayed Autonomous Selfing in Salvia umbratica (Lamiaceae). FRONTIERS IN PLANT SCIENCE 2021; 12:635310. [PMID: 34381465 PMCID: PMC8351595 DOI: 10.3389/fpls.2021.635310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 06/29/2021] [Indexed: 06/13/2023]
Abstract
Delayed autonomous selfing (DAS) provides reproductive assurance under conditions of pollinator and/or pollen-limitation. Few plant species have been investigated to determine if DAS is terminated when a flower is sufficiently pollinated by a pollen vector, thereby saving plant resources for other purposes. We examined this possibility in bumblebee-pollinated Salvia umbratica. We first showed that DAS resulting in high fruit set (100%) and seed set (>80%) per flower occurred in the absence of insect pollinators by means of style recurvature and was completed in 94% of flowers 72 h after they opened. In contrast, in flowers pollinated immediately after opening, DAS was prevented by corollas dropping away before styles recurve toward the upper thecae. We next showed that hand-pollination of flowers immediately after they opened resulted in high fruit set (100%) and seed set (>80%) when 5-10 pollen grains or more were deposited on their stigmas, whereas fruit set and seed set were reduced to 45.00 and 22.50%, respectively, when pollen loads were reduced to 1-3 pollen grains. Finally, we showed that on average single pollinator visits deposited 26 pollen grains on stigmas of flowers that had just opened, which is more than enough to ensure high fruit and seed set. Our results indicate that flower longevity is highly correlated with the pollinator environment and female fitness of S. umbratica, with extended flower longevity allowing DAS to occur being advantageous when pollinators are absent, while reduced floral longevity and prevention of DAS being favored when flowers are pollinated by pollinators. Thus, flower longevity in S. umbratica varies so as to optimize reproductive output and resource efforts, and is dependent on the availability and effectiveness of pollinators to pollinate flowers.
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Affiliation(s)
- Han-Wen Xiao
- Shanghai Chenshan Botanical Garden, Shanghai, China
- Eastern China Conservation Center for Wild Endangered Plant Resources, Shanghai, China
| | - Yan-Bo Huang
- Shanghai Chenshan Botanical Garden, Shanghai, China
- Eastern China Conservation Center for Wild Endangered Plant Resources, Shanghai, China
| | - Yu-Hang Chang
- Yunnan Key Laboratory for Integrative Conservation of Plant Species With Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Yun Chen
- Shanghai Chenshan Botanical Garden, Shanghai, China
- Eastern China Conservation Center for Wild Endangered Plant Resources, Shanghai, China
| | - Richard J. Abbott
- School of Biology, University of St Andrews, St Andrews, United Kingdom
| | - Yu-Kun Wei
- Shanghai Chenshan Botanical Garden, Shanghai, China
- Eastern China Conservation Center for Wild Endangered Plant Resources, Shanghai, China
| | - Yong-Peng Ma
- Yunnan Key Laboratory for Integrative Conservation of Plant Species With Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
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Wu C, Paciorek M, Liu K, LeClere S, Perez‐Jones A, Westra P, Sammons RD. Investigating the presence of compensatory evolution in dicamba resistant IAA16 mutated kochia (Bassia scoparia) †. PEST MANAGEMENT SCIENCE 2021; 77:1775-1785. [PMID: 33236492 PMCID: PMC7986355 DOI: 10.1002/ps.6198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 11/02/2020] [Accepted: 11/24/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Lack of fitness costs has been reported for multiple herbicide resistance traits, but the underlying evolutionary mechanisms are not well understood. Compensatory evolution that ameliorates resistance costs, has been documented in bacteria and insects but rarely studied in weeds. Dicamba resistant IAA16 (G73N) mutated kochia was previously found to have high fecundity in the absence of competition, regardless of significant vegetative growth defects. To understand if costs of dicamba resistance can be compensated through traits promoting reproductive success in kochia, we thoroughly characterized the reproductive growth and development of different G73N kochia biotypes. Flowering phenology, seed production and reproductive allocation were quantified through greenhouse studies, floral (stigma-anthers distance) and seed morphology, as well as resulting mating and seed dispersal systems were studied through time-course microcopy images. RESULTS G73N covaried with multiple phenological, morphological and ecological traits that improve reproductive fitness: (i) 16-60% higher reproductive allocation; (ii) longer reproduction phase through early flowering (2-7 days); (iii) smaller stigma-anthers separation (up to 60% reduction of herkogamy and dichogamy) that can potentially promote selfing and reproductive assurance; (iv) 'winged' seeds with 30-70% longer sepals that facilitate long-distance seed dispersal. CONCLUSION The current study demonstrates that costs of herbicide resistance can be ameliorated through coevolution of other fitness penalty alleviating traits. As illustrated in a hypothetical model, the evolution of herbicide resistance is an ongoing fitness maximization process, which poses challenges to contain the spread of resistance. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Chenxi Wu
- Department of Plant BiotechnologyBayer CropScienceChesterfieldMOUSA
| | - Marta Paciorek
- Department of Plant BiotechnologyBayer CropScienceChesterfieldMOUSA
| | - Kang Liu
- Department of Plant BiotechnologyBayer CropScienceChesterfieldMOUSA
| | - Sherry LeClere
- Department of Plant BiotechnologyBayer CropScienceChesterfieldMOUSA
| | | | - Phil Westra
- Department of Agricultural BiologyColorado State UniversityFort CollinsCOUSA
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Christopher DA, Karron JD, Semski WR, Smallwood PA, Trapnell DW, Mitchell RJ. Selfing rates vary with floral display, pollinator visitation and plant density in natural populations of Mimulus ringens. J Evol Biol 2021; 34:803-815. [PMID: 33704852 PMCID: PMC8252063 DOI: 10.1111/jeb.13781] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 02/01/2021] [Accepted: 02/25/2021] [Indexed: 11/27/2022]
Abstract
Variation in selfing rates within and among populations of hermaphroditic flowering plants can strongly influence the evolution of reproductive strategies and the genetic structure of populations. This intraspecific variation in mating patterns may reflect both genetic and ecological factors, but the relative importance of these factors remains poorly understood. Here, we explore how selfing in 13 natural populations of the perennial wildflower Mimulus ringens is influenced by (a) pollinator visitation, an ecological factor, and (b) floral display, a trait with a genetic component that also responds to environmental variation. We also explore whether genetically based floral traits, including herkogamy, affect selfing. We found substantial variation among populations in selfing rate (0.13–0.55). Selfing increased strongly and significantly with floral display, among as well as within populations. Selfing also increased at sites with lower pollinator visitation and low plant density. However, selfing was not correlated with floral morphology. Overall, these results suggest that pollinator visitation and floral display, two factors that interact to affect geitonogamous pollinator movements, can influence the selfing rate. This study identifies mechanisms that may play a role in maintaining selfing rate variation among populations.
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Affiliation(s)
- Dorothy A Christopher
- Department of Biological Sciences, University of Wisconsin - Milwaukee, Milwaukee, WI, USA
| | - Jeffrey D Karron
- Department of Biological Sciences, University of Wisconsin - Milwaukee, Milwaukee, WI, USA
| | - Wendy R Semski
- Department of Biological Sciences, University of Wisconsin - Milwaukee, Milwaukee, WI, USA
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Murúa M, Espíndola A, Pérez F. Self-Compatibility Not Associated with Morphological or Genetic Diversity Reduction in Oil-Rewarding Calceolaria Species. PLANTS 2020; 9:plants9101377. [PMID: 33081098 PMCID: PMC7602863 DOI: 10.3390/plants9101377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/28/2020] [Accepted: 10/09/2020] [Indexed: 11/16/2022]
Abstract
One of the most common evolutionary transitions in angiosperms is the reproductive change from outcrossing to selfing, commonly associated with changes in floral biology and genetic diversity. Here, we aim to test whether self-compatibility leads to a reduction of floral traits and genetic diversity. For this, we experimentally estimate levels of self-compatibility, measure three floral traits and estimate four genetic diversity parameters using nine microsatellites in nine Calceolaria species. Our analysis indicated that four of the study species were self-incompatible. In addition, we found that self-compatible species did not show a reduction in floral traits size, but rather displayed larger corolla and elaiophore areas. Our analyses of genetic diversity identified larger allele number and observed heterozygosity in selfers than in outcrossers, but did not find larger inbreeding in the self-compatible species. Even though our results contradict our expectations, in the case of Calceolaria, their high dependence on only two genera of oil-bees puts the genus in a vulnerable reproductive position, probably facilitating the evolution of reproductive assurance mechanisms in the absence of pollinators. As a result, plants maintain their pollinator attraction traits while evolving the ability to self, possibly in a delayed way.
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Affiliation(s)
- Maureen Murúa
- Centro GEMA, Genómica, Ecología y Medio Ambiente, Facultad de Estudios Interdisciplinarios, Universidad Mayor, Camino La Pirámide 5750, Santiago 8580745, Chile
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago 8331150, Chile;
- Correspondence:
| | - Anahí Espíndola
- Department of Entomology, Plant Sciences Building 3138, University of Maryland, College Park, MD 20742-4454, USA;
| | - Fernanda Pérez
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago 8331150, Chile;
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Ruane LG, Mangum SM, Horner KM, Moeller DA. The opportunity for outcrossing varies across the geographic range of the primarily selfing Clarkia xantiana ssp. parviflora. AMERICAN JOURNAL OF BOTANY 2020; 107:1198-1207. [PMID: 32700343 DOI: 10.1002/ajb2.1510] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 02/22/2020] [Indexed: 06/11/2023]
Abstract
PREMISE The timing of self-fertilization has potentially important consequences for the trajectory of mating system evolution, the opportunity for outcrossing, and the maintenance of genetic variation in populations. For primarily selfing taxa, it remains poorly understood as to how floral variation influences the opportunity for outcrossing and whether those attributes vary among populations across geographic ranges. METHODS We examined variation in floral traits (herkogamy, protandry, flower size, stigma stage at anthesis, timing of stigma receptivity) in seven populations of Clarkia xantiana ssp. parviflora, a primarily selfing taxon, spanning from the western to eastern margins of its distribution. We also performed experimental emasculations and pollinations (followed by stigma severing) to quantify the extent of opportunities for outcrossing across flower development. RESULTS There was marked among-population variation in all floral traits, particularly between far eastern and western populations. Emasculation experiments showed that the eastern populations had minimal autonomous selfing, but western populations had high rates of selfing within 24 h after anthesis. Population variation in autofertility was significantly predicted by floral trait variation, especially protandry and petal size. CONCLUSIONS Greater protandry both extended the time over which outcrossing could potentially occur and reduced the probability of autonomous selfing, suggesting that there may be a tradeoff that results in fitness loss when pollinator visits are not common. The east-west pattern of differentiation in some floral traits parallels that of postglacial range expansion, suggesting that selection on the mating system may have been strong in the process of range expansion.
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Affiliation(s)
- Lauren G Ruane
- Department of Organismal and Environmental Biology, Christopher Newport University, 1 Avenue of the Arts, Newport News, Virginia, 23606, United States
| | - Samantha M Mangum
- Department of Organismal and Environmental Biology, Christopher Newport University, 1 Avenue of the Arts, Newport News, Virginia, 23606, United States
| | - Kaitlyn M Horner
- Department of Organismal and Environmental Biology, Christopher Newport University, 1 Avenue of the Arts, Newport News, Virginia, 23606, United States
| | - David A Moeller
- Department of Plant and Microbial Biology, University of Minnesota, 1479 Gortner Avenue, St. Paul, Minnesota, 55108, United States
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Bartoš M, Janeček Š, Janečková P, Chmelová E, Tropek R, Götzenberger L, Klomberg Y, Jersáková J. Are Reproductive Traits Related to Pollen Limitation in Plants? A Case Study from a Central European Meadow. PLANTS 2020; 9:plants9050640. [PMID: 32438589 PMCID: PMC7285000 DOI: 10.3390/plants9050640] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/07/2020] [Accepted: 05/16/2020] [Indexed: 11/16/2022]
Abstract
The deficiency of pollen grains for ovule fertilization can be the main factor limiting plant reproduction and fitness. Because of the ongoing global changes, such as biodiversity loss and landscape fragmentation, a better knowledge of the prevalence and predictability of pollen limitation is challenging within current ecological research. In our study we used pollen supplementation to evaluate pollen limitation (at the level of seed number and weight) in 22 plant species growing in a wet semi-natural meadow. We investigated the correlation between the pollen limitation index (PL) and floral traits associated with plant reproduction or pollinator foraging behavior. We recorded significant pollen limitation for approximately 41% of species (9 out of 22 surveyed). Seven species had a significant positive response in seed production and two species increased in seed weight after pollen supplementation. Considering traits, PL significantly decreased with the number of pollinator functional groups. The relationship of PL with other examined traits was not supported by our results. The causes of pollen limitation may vary among species with regard to (1) different reproductive strategies and life history, and/or (2) temporary changes in influence of biotic and abiotic factors at a site.
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Affiliation(s)
- Michael Bartoš
- Institute of Botany, The Czech Academy of Sciences, 37981 Třeboň, Czech Republic;
- Correspondence: ; Tel.:+420-380-720-330
| | - Štěpán Janeček
- Department of Ecology, Faculty of Science, Charles University, 12843 Praha, Czech Republic; (Š.J.); (P.J.); (E.C.); (R.T.); (Y.K.)
| | - Petra Janečková
- Department of Ecology, Faculty of Science, Charles University, 12843 Praha, Czech Republic; (Š.J.); (P.J.); (E.C.); (R.T.); (Y.K.)
- Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic;
| | - Eliška Chmelová
- Department of Ecology, Faculty of Science, Charles University, 12843 Praha, Czech Republic; (Š.J.); (P.J.); (E.C.); (R.T.); (Y.K.)
- Biology Centre, Institute of Entomology, The Czech Academy of Sciences, 37005 České Budějovice, Czech Republic
| | - Robert Tropek
- Department of Ecology, Faculty of Science, Charles University, 12843 Praha, Czech Republic; (Š.J.); (P.J.); (E.C.); (R.T.); (Y.K.)
- Biology Centre, Institute of Entomology, The Czech Academy of Sciences, 37005 České Budějovice, Czech Republic
| | - Lars Götzenberger
- Institute of Botany, The Czech Academy of Sciences, 37981 Třeboň, Czech Republic;
- Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic;
| | - Yannick Klomberg
- Department of Ecology, Faculty of Science, Charles University, 12843 Praha, Czech Republic; (Š.J.); (P.J.); (E.C.); (R.T.); (Y.K.)
| | - Jana Jersáková
- Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic;
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Bartoš M, Janeček Š, Janečková P, Padyšáková E, Tropek R, Götzenberger L, Klomberg Y, Jersáková J. Self-compatibility and autonomous selfing of plants in meadow communities. PLANT BIOLOGY (STUTTGART, GERMANY) 2020; 22:120-128. [PMID: 31549455 DOI: 10.1111/plb.13049] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 08/30/2019] [Indexed: 06/10/2023]
Abstract
One of the most fundamental, although controversial, questions related to the evolution of plant mating systems is the distribution of outcrossing rates. Self-compatibility, and especially autonomous self-pollination, can become particularly beneficial in anthropogenically degraded habitats with impoverished pollinator assemblages and increased pollen limitation. In a hand-pollination experiment with 46 meadow plants from the Železné hory Mts., Czech Republic, we evaluated the species' ability to adopt different mating systems. For a subset of the species, we also tested seed germination for inbreeding depression. Subsequently, we analysed relationships between the species' mating systems and 12 floral and life-history traits. We found a relatively discrete distribution of the studied species into four groups. Fully and partially self-incompatible species formed the largest group, followed by self-compatible non-selfers and mixed mating species. The germination experiment showed an absence of inbreeding depression in 19 out of 22 examined species. Nectar sugar per flower, nectar sugar per shoot and dichogamy were significant associated with the mating system. Spontaneous selfing ability and self-incompatibility in species of the meadow communities had a discrete distribution, conforming to the general distribution of mating and breeding systems in angiosperms. The low frequency of spontaneous selfers and the lack of inbreeding depression at germination suggest the existence of a selection against selfing at the later ontogenetic stages. Some floral traits, such as the level of dichogamy and amount of nectar reward, may strongly impact the balance between selfing and outcrossing rates in the self-compatible species and thus shape the evolution of mating systems.
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Affiliation(s)
- M Bartoš
- Institute of Botany, The Czech Academy of Sciences, Třeboň, Czech Republic
| | - Š Janeček
- Department of Ecology, Faculty of Science, Charles University, Praha, Czech Republic
| | - P Janečková
- Department of Ecology, Faculty of Science, Charles University, Praha, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - E Padyšáková
- Department of Ecology, Faculty of Science, Charles University, Praha, Czech Republic
- Biology Centre, Institute of Entomology, The Czech Academy of Sciences, České Budějovice, Czech Republic
| | - R Tropek
- Department of Ecology, Faculty of Science, Charles University, Praha, Czech Republic
- Biology Centre, Institute of Entomology, The Czech Academy of Sciences, České Budějovice, Czech Republic
| | - L Götzenberger
- Institute of Botany, The Czech Academy of Sciences, Třeboň, Czech Republic
| | - Y Klomberg
- Department of Ecology, Faculty of Science, Charles University, Praha, Czech Republic
| | - J Jersáková
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
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Razanajatovo M, Fischer L, van Kleunen M. Do floral traits and the selfing capacity of Mimulus guttatus plastically respond to experimental temperature changes? Oecologia 2019; 192:261-272. [PMID: 31760481 DOI: 10.1007/s00442-019-04558-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 11/11/2019] [Indexed: 01/08/2023]
Abstract
Climate change can negatively impact plant-pollinator interactions, and reduce outcross pollination. For reproductive assurance, an increased capacity for autonomous selfing should benefit the persistence of plants under new temperature conditions. Plastic responses of the autonomous selfing capacity to climate change may occur indirectly due to changes in floral traits associated with this capacity. We tested whether the mixed mating plant Mimulus guttatus is capable of plastic changes in floral traits favoring autonomous selfing in response to temperature changes. In seven growth chambers, we grew M. guttatus originating from a large range of latitudes (from 37.89° N to 49.95° N) and thus home temperatures in North America, and experimentally assessed the (autonomous) selfing and outcrossing capacities of the plants. With an increase in the difference between the overall mean daytime and nighttime experimental test temperature and home temperature, flower length and width decreased. The plastic response in flower size suggests that plants may be more successful at autonomous selfing. However, we did not find direct evidence that M. guttatus responded to increased temperature by an increased autonomous selfing capacity. With an increase in temperature difference, the odds of seed production, number of seeds, and individual seed mass decreased. Our results indicate that global warming and the associated increase in extreme temperature events may be detrimental to the reproduction and thus persistence of some plants.
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Affiliation(s)
- Mialy Razanajatovo
- Ecology, Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Constance, Germany.
| | - Liliana Fischer
- Ecology, Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Constance, Germany
| | - Mark van Kleunen
- Ecology, Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Constance, Germany.,Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou, 318000, China
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Hildesheim LS, Opedal ØH, Armbruster WS, Pélabon C. Fitness costs of delayed pollination in a mixed-mating plant. ANNALS OF BOTANY 2019; 124:869-881. [PMID: 31504153 PMCID: PMC6868360 DOI: 10.1093/aob/mcz141] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 08/14/2019] [Indexed: 06/01/2023]
Abstract
BACKGROUND AND AIMS To predict the evolutionary consequences of pollinator declines, we need to understand the evolution of delayed autonomous self-pollination, which is expected to evolve as a mechanism of reproductive assurance when cross-pollination becomes unreliable. This involves estimating the costs of increased levels of selfing as well as those associated with floral senescence. METHODS We studied the mechanisms and costs of delayed self-pollination in the mixed-mating vine Dalechampia scandens (Euphorbiaceae) by first assessing among-population variation in herkogamy and dichogamy, which together determine the rate and timing of autonomous self-pollination. We then tested whether floral longevity responds plastically to delayed pollination. Finally, we assessed the costs of delayed self-pollination in terms of seed number and size, explicitly separating inbreeding depression from effects of floral senescence. KEY RESULTS Herkogamy varied extensively, while variation in dichogamy was more limited. Unpollinated blossoms increased their longevity, but seed quantity and quality decreased with increasing delays in pollination, independently of inbreeding depression. CONCLUSIONS In D. scandens, earlier autonomous selfing is facilitated by reduced herkogamy rather than reduced protogyny, providing reproductive assurance while maintaining the possibility for outcrossing events. Effective early autonomous self-pollination may evolve under reduced cross-pollination reliability in response to costs associated with floral senescence.
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Affiliation(s)
- Laura S Hildesheim
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, NTNU, Trondheim, Norway
| | - Øystein H Opedal
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, NTNU, Trondheim, Norway
- Research Centre for Ecological Change, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - W Scott Armbruster
- School of Biological Sciences, King Henry Building, King Henry I Street, University of Portsmouth, Portsmouth, UK
- Institute of Arctic Biology, University of Alaska, Fairbanks, AK, USA
| | - Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, NTNU, Trondheim, Norway
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15
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Koski MH, Galloway LF, Busch JW. Pollen limitation and autonomous selfing ability interact to shape variation in outcrossing rate across a species range. AMERICAN JOURNAL OF BOTANY 2019; 106:1240-1247. [PMID: 31415107 DOI: 10.1002/ajb2.1342] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 06/28/2019] [Indexed: 06/10/2023]
Abstract
PREMISE Hermaphroditic plants commonly reproduce through a mixture of selfing and outcrossing. The degree to which outcrossing rates reflect the availability of outcross pollen, genetic differentiation in the ability to autonomously self-fertilize, or both is often unclear. Despite the potential for autonomy and the pollination environment to jointly influence outcrossing, this interaction is rarely studied. METHODS We reviewed studies from the literature that tested whether the pollination environment or floral traits that cause autonomous selfing predict variation in outcrossing rate among populations. We also measured outcrossing rates in 23 populations of Campanula americana and examined associations with the pollination environment, autonomy, and their interaction. RESULTS Our review revealed that traits that facilitate selfing were often negatively associated with outcrossing rates whereas most aspects of the pollination environment poorly predicted outcrossing. Populations of C. americana varied from mixed mating to highly outcrossing, but variation was unrelated to population size, density, pollen limitation, or autonomous selfing ability. Outcrossing rate was significantly influenced by an interaction between autonomous selfing ability and pollen limitation. Across highly autonomous populations, elevated pollen limitation was associated with reduced outcrossing, while there was no relationship for less autonomous populations. CONCLUSIONS Both the ability to self autonomously and pollen limitation interact to shape outcrossing rates in C. americana. This work suggests that autonomy affords mating-system flexibility, though it is not ubiquitous in all populations across the species range. Interactions between traits influencing autonomy and pollen limitation are likely to explain variation in outcrossing rates among populations of flowering plants.
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Affiliation(s)
- Matthew H Koski
- Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, Virginia, 22904, USA
- Department of Biological Sciences, Clemson University, 132 Long Hall, Clemson, South Carolina, 29631, USA
| | - Laura F Galloway
- Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, Virginia, 22904, USA
| | - Jeremiah W Busch
- School of Biological Sciences, Washington State University, P.O. Box 644236, Pullman, Washington, 99164, USA
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Kostyun JL, Gibson MJS, King CM, Moyle LC. A simple genetic architecture and low constraint allow rapid floral evolution in a diverse and recently radiating plant genus. THE NEW PHYTOLOGIST 2019; 223:1009-1022. [PMID: 30972773 DOI: 10.1111/nph.15844] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/02/2019] [Indexed: 06/09/2023]
Abstract
Genetic correlations among different components of phenotypes, especially those resulting from pleiotropy, can constrain or facilitate trait evolution. These factors could especially influence the evolution of traits that are functionally integrated, such as those comprising the flower. Indeed, pleiotropy is proposed as a main driver of repeated convergent trait transitions, including the evolution of phenotypically similar pollinator syndromes. We assessed the role of pleiotropy in the differentiation of floral and other reproductive traits between two species - Jaltomata sinuosa and J. umbellata (Solanaceae) - that have divergent suites of floral traits consistent with bee and hummingbird pollination, respectively. To do so, we generated a hybrid population and examined the genetic architecture (trait segregation and quantitative trait locus (QTL) distribution) underlying 25 floral and fertility traits. We found that most floral traits had a relatively simple genetic basis (few, predominantly additive, QTLs of moderate to large effect), as well as little evidence of antagonistic pleiotropy (few trait correlations and QTL colocalization, particularly between traits of different classes). However, we did detect a potential case of adaptive pleiotropy among floral size and nectar traits. These mechanisms may have facilitated the rapid floral trait evolution observed within Jaltomata, and may be a common component of rapid phenotypic change more broadly.
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Affiliation(s)
- Jamie L Kostyun
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
- Department of Plant Biology, The University of Vermont, Burlington, VT, 05405, USA
| | | | - Christian M King
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH, 43210, USA
| | - Leonie C Moyle
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
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17
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Leibman L, Rowe A, Koski MH, Galloway LF. Populations with greater flexibility in floral traits modify mating system in response to the pollinator environment. Funct Ecol 2018. [DOI: 10.1111/1365-2435.13093] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Lia Leibman
- Department of Biology and Mountain Lake Biological Station University of Virginia Charlottesville VA USA
| | - Anne Rowe
- Department of Biology and Mountain Lake Biological Station University of Virginia Charlottesville VA USA
| | - Matthew H. Koski
- Department of Biology and Mountain Lake Biological Station University of Virginia Charlottesville VA USA
| | - Laura F. Galloway
- Department of Biology and Mountain Lake Biological Station University of Virginia Charlottesville VA USA
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Goodwillie C, Weber JJ. The best of both worlds? A review of delayed selfing in flowering plants. AMERICAN JOURNAL OF BOTANY 2018; 105:641-655. [PMID: 29630718 DOI: 10.1002/ajb2.1045] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 01/17/2018] [Indexed: 05/27/2023]
Abstract
PREMISE OF STUDY In a seminal body of theory, Lloyd showed that the fitness consequences of selfing will depend on its timing in anthesis. Selfing that occurs after opportunities for outcrossing or pollen dispersal can provide reproductive assurance when pollinators are limited and is expected to incur little cost, even when inbreeding depression is high. As a result, delayed selfing is often interpreted as a "best-of-both-worlds" mating system that combines the advantages of selfing and outcrossing. METHODS We surveyed 65 empirical studies of delayed selfing, recording floral mechanisms and examining information on inbreeding depression, autofertility, and other parameters to test the support for delayed selfing as a best-of-both-worlds strategy. KEY RESULTS Phylogenetic distribution of the diverse floral mechanisms suggests that some basic floral structures may predispose plant taxa to evolve delayed selfing. Delayed selfing appears to serve as a best-of-both-worlds strategy in some but not all species. While the capacity for autonomous selfing is often high, it is lower, in some cases, than in related species with earlier modes of selfing. In other delayed-selfers, low inbreeding depression and reduced investment in corollas and pollen suggest limited benefits from outcrossing. CONCLUSIONS Despite a growing literature on the subject, experimental evidence for delayed selfing is limited and major gaps in knowledge remain, particularly with respect to the stability of delayed selfing and the conditions that may favor transitions between delayed and earlier selfing. Finally, we suggest a potential role of delayed selfing in facilitating transitions from self-incompatibility to selfing.
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Affiliation(s)
- Carol Goodwillie
- East Carolina University, Department of Biology, Howell Science Building, Greenville, NC, 27858
| | - Jennifer J Weber
- Southeast Missouri State University, Department of Biology, One University Plaza, MS 6200, Cape Girardeau, MO, 63701
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19
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Correlation between the timing of autonomous selfing and floral traits: a comparative study from three selfing Gentianopsis species (Gentianaceae). Sci Rep 2018; 8:3634. [PMID: 29483537 PMCID: PMC5827715 DOI: 10.1038/s41598-018-21930-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 02/13/2018] [Indexed: 11/11/2022] Open
Abstract
About 20% of angiosperms employ self-fertilization as their main mating strategy. In this study, we aimed to examine how the selfing timing correlated with floral traits in three Gentianopsis species in which autonomous selfing is achieved through filament elongation. Although the three Gentianopsis species exhibit no significant variation in their capacity for autonomous selfing, flowers of G. grandis last longer, are larger and have a higher corolla biomass, P/O ratios and male biomass allocation than those of G. paludosa, and especially those of G. contorta. Autonomous selfing occurs in the early floral life of G. paludosa and G. contorta and in the later floral life of G. grandis. Seed production mainly results from autonomous selfing in G. paludosa and G. contorta; however, G. grandis could be more described as having a mixed mating system. We suggest that autonomous selfing in later floral life increases the chance of cross-pollination prior to this, while autonomous selfing in early floral life offers a selective advantage to plants by reducing the resource investment in traits that may increase pollinator attraction and visitation.
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20
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Koski MH, Kuo L, Niedermaier KM, Galloway LF. Timing is everything: Dichogamy and pollen germinability underlie variation in autonomous selfing among populations. AMERICAN JOURNAL OF BOTANY 2018; 105:241-248. [PMID: 29578289 DOI: 10.1002/ajb2.1025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 12/29/2017] [Indexed: 06/08/2023]
Abstract
PREMISE OF THE STUDY The evolution of multiple floral traits often underlies the transition from outcrossing to selfing. Such traits can influence the ability to self, and the timing at which selfing occurs, which in turn affects the costs of selfing. Species that display variation in autonomous selfing provide an opportunity to dissect the phenotypic changes that contribute to variability in the mating system. METHODS In a common garden, we measured dichogamy and herkogamy in 24 populations of the protandrous mixed-mating herb Campanula americana, and related these to autonomous fruit set (autonomy). We then measured the timing of self-pollen deposition and fruit production in populations with high and low autonomy, and determined whether pollen germinability across floral development contributes to variation in autonomy. KEY RESULTS Populations that transitioned more rapidly to female phase displayed elevated autonomous selfing, but herkogamy was unassociated with autonomous selfing. Selfing occurred more rapidly in highly autonomous populations because of greater self-pollen deposition early in female phase. Pollen germinability in low-autonomy populations remained constant across floral development, but in high-autonomy populations it increased after floral anthesis and was highest near the onset of female phase. CONCLUSIONS Reduced dichogamy, elevated self-pollen deposition, and higher pollen germination late in male phase contribute to both earlier selfing and greater selfing. These traits vary among populations, likely reflecting past selection on the mating system. While delayed selfing bears fewer fitness costs, the evolution of earlier selfing may be favored if self-pollen availability decreases over floral development.
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Affiliation(s)
- Matthew H Koski
- Department of Biology, University of Virginia, 057 Gilmer Hall, Charlottesville, VA, USA
| | - Liao Kuo
- Wuhan Botanical Garden, Chinese Academy of Science, Moshan Wuchang, Wuhan, P.R. China, 430074
| | - Kerstin M Niedermaier
- Department of Biology, University of Virginia, 057 Gilmer Hall, Charlottesville, VA, USA
| | - Laura F Galloway
- Department of Biology, University of Virginia, 057 Gilmer Hall, Charlottesville, VA, USA
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Toräng P, Vikström L, Wunder J, Wötzel S, Coupland G, Ågren J. Evolution of the selfing syndrome: Anther orientation and herkogamy together determine reproductive assurance in a self-compatible plant. Evolution 2017; 71:2206-2218. [PMID: 28722132 DOI: 10.1111/evo.13308] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/22/2017] [Accepted: 06/22/2017] [Indexed: 01/04/2023]
Abstract
Capacity for autonomous self-fertilization provides reproductive assurance, has evolved repeatedly in the plant kingdom, and typically involves several changes in flower morphology and development (the selfing syndrome). Yet, the relative importance of different traits and trait combinations for efficient selfing and reproductive success in pollinator-poor environments is poorly known. In a series of experiments, we tested the importance of anther-stigma distance and the less studied trait anther orientation for efficiency of selfing in the perennial herb Arabis alpina. Variation in flower morphology among eight self-compatible European populations was correlated with efficiency of self-pollination and with pollen limitation in a common-garden experiment. To examine whether anther-stigma distance and anther orientation are subject to directional and/or correlational selection, and whether this is because these traits affect pollination success, we planted a segregating F2 population at two native field sites. Selection strongly favored a combination of introrse anthers and reduced anther-stigma distance at a site where pollinator activity was low, and supplemental hand-pollination demonstrated that this was largely because of their effect on securing self-pollination. The results suggest that concurrent shifts in more than one trait can be crucial for the evolution of efficient self-pollination and reproductive assurance in pollinator-poor habitats.
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Affiliation(s)
- Per Toräng
- Department of Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden.,School of Bioscience, University of Skövde, Box 408, SE-541 28, Skövde, Sweden
| | - Linus Vikström
- Department of Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden
| | - Jörg Wunder
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Carl von Linné Weg 10, 50829, Cologne, Germany
| | - Stefan Wötzel
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Carl von Linné Weg 10, 50829, Cologne, Germany
| | - George Coupland
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Carl von Linné Weg 10, 50829, Cologne, Germany
| | - Jon Ågren
- Department of Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden
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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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Rosas-Guerrero V, Hernández D, Cuevas E. Influence of pollen limitation and inbreeding depression in the maintenance of incomplete dichogamy in Salvia elegans. Ecol Evol 2017. [PMID: 28649325 PMCID: PMC5478062 DOI: 10.1002/ece3.2827] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The widespread presence of incomplete dichogamy (i.e., partial separation in time between male and female phases) in flowering plants is a long‐standing question in floral evolution. In this study, we proposed four scenarios in which depending on the particular combination of pollen limitation and inbreeding depression, the presence of complete dichogamy, incomplete dichogamy, or adichogamy may be favored. Moreover, we evaluated the role of pollen limitation and inbreeding depression in a natural population of Salvia elegans to test the validity of our predicted scenarios. Our results indicate that S. elegans is partially protandrous as pollen viability and stigma receptivity overlap in the last days of life of the flower. Furthermore, through pollination treatments, we found no evidence of pollen limitation or inbreeding depression in any of the evaluated fitness components. As expected by one of the proposed scenarios, incomplete dichogamy seems to be favored in plants with absence of inbreeding depression and pollen limitation as a way to diminish interference between male and female functions.
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Affiliation(s)
- Víctor Rosas-Guerrero
- Facultad en Desarrollo Sustentable Campus Costa Grande Universidad Autónoma de Guerrero Tecpan de Galeana Guerrero México
| | - Diego Hernández
- Facultad de Biología Universidad Michoacana de San Nicolás de Hidalgo Morelia Michoacán México
| | - Eduardo Cuevas
- Facultad de Biología Universidad Michoacana de San Nicolás de Hidalgo Morelia Michoacán México
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Geographic variation in floral traits and the capacity of autonomous selfing across allopatric and sympatric populations of two closely related Centaurium species. Sci Rep 2017; 7:46410. [PMID: 28429781 PMCID: PMC5399455 DOI: 10.1038/srep46410] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 03/07/2017] [Indexed: 02/02/2023] Open
Abstract
Floral traits and the relative contribution of autonomous selfing to total seed set varies geographically and is often driven by the availability and abundance of suitable pollinators and/or the presence of co-flowering relatives. In the latter case, competition for pollinator services and costs of hybridization can select for floral traits that reduce interspecific gene flow and contribute to prezygotic isolation, potentially leading to geographic variation in floral divergence between allopatric and sympatric populations. In this study, we investigated variation in floral traits and its implications on the capacity of autonomous selfing in both allopatric and sympatric populations of two closely related Centaurium species(Gentianaceae) across two distinct geographic regions(UK and mainland Europe). Although the magnitude and direction of floral differentiation varied between regions, sympatric populations were always significantly more divergent in floral traits and the capacity to self autonomously than allopatric populations. These results indicate that mating systems can vary substantially within a species and that the joint occurrence of plant species can have a major impact on floral morphology and capacity of autonomous selfing, most likely as a way to reduce the probability of interspecific interference.
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Opedal ØH, Albertsen E, Armbruster WS, Pérez-Barrales R, Falahati-Anbaran M, Pélabon C. Evolutionary consequences of ecological factors: pollinator reliability predicts mating-system traits of a perennial plant. Ecol Lett 2016; 19:1486-1495. [DOI: 10.1111/ele.12701] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 10/14/2016] [Indexed: 12/23/2022]
Affiliation(s)
- Øystein H. Opedal
- Centre for Biodiversity Dynamics; Department of Biology; Norwegian University of Science and Technology, NTNU; 7491 Trondheim Norway
| | - Elena Albertsen
- Centre for Biodiversity Dynamics; Department of Biology; Norwegian University of Science and Technology, NTNU; 7491 Trondheim Norway
| | - W. Scott Armbruster
- School of Biological Sciences; University of Portsmouth; King Henry Building, King Henry I Street Portsmouth PO1 2DY UK
- Department of Biology; Norwegian University of Science and Technology, NTNU; 7491 Trondheim Norway
- Institute of Arctic Biology; University of Alaska; Fairbanks AK 99775 USA
| | - Rocío Pérez-Barrales
- School of Biological Sciences; University of Portsmouth; King Henry Building, King Henry I Street Portsmouth PO1 2DY UK
| | - Mohsen Falahati-Anbaran
- School of Biology and Center of Excellence in Phylogeny of Living Organisms; University of Tehran; 14155-6455 Tehran Iran
| | - Christophe Pélabon
- Centre for Biodiversity Dynamics; Department of Biology; Norwegian University of Science and Technology, NTNU; 7491 Trondheim Norway
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Rosenheim JA, Williams NM, Schreiber SJ, Rapp JM. Modest Pollen Limitation of Lifetime Seed Production Is in Good Agreement with Modest Uncertainty in Whole-Plant Pollen Receipt. Am Nat 2016; 187:397-404. [PMID: 26913951 DOI: 10.1086/684849] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We recently introduced a model that predicts the degree to which a plant's lifetime seed production may be constrained by unpredictable shortfalls of pollen receipt ("pollen limitation"). Burd's comment in this issue criticized our analysis, first by arguing that the empirical literature documents much higher levels of pollen limitation than our model predicts and then suggesting that the apparent discrepancy stemmed from our (1) underestimating the costs of securing a fertilized ovule and (2) assuming too little unpredictability in whole-plant pollen receipt. We reply as follows. First, the empirical literature must be consulted carefully. Burd relies on pollen supplementation experiments performed on parts of plants or on whole plants but during only one reproductive season for polycarpic perennials; in both cases, resource reallocation often leads to gross overestimates of pollen limitation. We comprehensively review pollen limitation estimates that are free of these estimation problems and find strong agreement with our model predictions. Second, although cost estimates for different components of seed production are imprecise, errors are likely to be small relative to the >1,000-fold differences observed across plant species, the primary focus of our article. Finally, contrary to Burd's argument, pollen receipt by entire plants is much more predictable than that by individual flowers because the flower-to-flower variation "averages out" when summed across many flowers. Our model uses parameter values that are in broad agreement with the empirical record of modest plant-to-plant variation in pollen receipt and thus predicts the generally modest pollen limitation that is observed in nature.
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Bontrager M, Angert AL. Effects of range-wide variation in climate and isolation on floral traits and reproductive output of Clarkia pulchella. AMERICAN JOURNAL OF BOTANY 2016; 103:10-21. [PMID: 26362193 DOI: 10.3732/ajb.1500091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Accepted: 05/28/2015] [Indexed: 05/11/2023]
Abstract
PREMISE OF THE STUDY Plant mating systems and geographic range limits are conceptually linked by shared underlying drivers, including landscape-level heterogeneity in climate and in species' abundance. Studies of how geography and climate interact to affect plant traits that influence mating system and population dynamics can lend insight to ecological and evolutionary processes shaping ranges. Here, we examined how spatiotemporal variation in climate affects reproductive output of a mixed-mating annual, Clarkia pulchella. We also tested the effects of population isolation and climate on mating-system-related floral traits across the range. METHODS We measured reproductive output and floral traits on herbarium specimens collected across the range of C. pulchella. We extracted climate data associated with specimens and derived a population isolation metric from a species distribution model. We then examined how predictors of reproductive output and floral traits vary among populations of increasing distance from the range center. Finally, we tested whether reproductive output and floral traits vary with increasing distance from the center of the range. KEY RESULTS Reproductive output decreased as summer precipitation decreased, and low precipitation may contribute to limiting the southern and western range edges of C. pulchella. High spring and summer temperatures are correlated with low herkogamy, but these climatic factors show contrasting spatial patterns in different quadrants of the range. CONCLUSIONS Limiting factors differ among different parts of the range. Due to the partial decoupling of geography and environment, examining relationships between climate, reproductive output, and mating-system-related floral traits reveals spatial patterns that might be missed when focusing solely on geographic position.
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Affiliation(s)
- Megan Bontrager
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Amy L Angert
- Departments of Botany and Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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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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de Waal C, Rodger JG, Anderson B, Ellis AG. Selfing ability and dispersal are positively related, but not affected by range position: a multispecies study on southern African Asteraceae. J Evol Biol 2014; 27:950-9. [PMID: 24735437 DOI: 10.1111/jeb.12368] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 02/19/2014] [Accepted: 03/07/2014] [Indexed: 11/30/2022]
Abstract
Dispersal and breeding system traits are thought to affect colonization success. As species have attained their present distribution ranges through colonization, these traits may vary geographically. Although several theories predict associations between dispersal ability, selfing ability and the relative position of a population within its geographic range, there is little theoretical or empirical consensus on exactly how these three variables are related. We investigated relationships between dispersal ability, selfing ability and range position across 28 populations of 13 annual, wind-dispersed Asteraceae species from the Namaqualand region of South Africa. Controlling for phylogeny, relative dispersal ability--assessed from vertical fall time of fruits--was positively related to an index of autofertility--determined from hand-pollination experiments. These findings support the existence of two discrete syndromes: high selfing ability associated with good dispersal and obligate outcrossing associated with lower dispersal ability. This is consistent with the hypothesis that selection for colonization success drives the evolution of an association between these traits. However, no general effect of range position on dispersal or breeding system traits was evident. This suggests selection on both breeding system and dispersal traits acts consistently across distribution ranges.
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Affiliation(s)
- C de Waal
- Department of Botany and Zoology, University of Stellenbosch, Matieland, 7601, South Africa
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Briscoe Runquist RD, Moeller DA. Floral and mating system divergence in secondary sympatry: testing an alternative hypothesis to reinforcement in Clarkia. ANNALS OF BOTANY 2014; 113:223-35. [PMID: 24081279 PMCID: PMC3890389 DOI: 10.1093/aob/mct218] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 07/24/2013] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS Reproductive character displacement (RCD) is often an important signature of reinforcement when partially cross-compatible taxa meet in secondary sympatry. In this study, floral evolution is examined during the Holocene range expansion of Clarkia xantiana subsp. parviflora from eastern Pleistocene refugia to a western zone of sympatry with its sister taxon, subsp. xantiana. Floral divergence between the two taxa is greater in sympatry than allopatry. The goal was to test an alternative hypothesis to reinforcement - that floral divergence of sympatric genotypes is simply a by-product of adaptation to pollination environments that differ between the allopatric and sympatric portions of the subspecies' range. METHODS Floral trait data from two common garden studies were used to examine floral divergence between sympatric and allopatric regions and among phylogeographically defined lineages. In natural populations of C. x. parviflora, the magnitude of pollen limitation and reproductive assurance were quantified across its west-to-east range. Potted sympatric and allopatric genotypes were also reciprocally translocated between geographical regions to distinguish between the effects of floral phenotype versus contrasting pollinator environments on reproductive ecology. KEY RESULTS Sympatric populations are considerably smaller flowered with reduced herkogamy. Pollen limitation and the reproductive assurance value of selfing are greater in sympatric than in allopatric populations. Most significantly, reciprocal translocation experiments showed these differences in reproductive ecology cannot be attributed to contrasting pollinator environments between the sympatric and allopatric regions, but instead reflect the effects of flower size on pollinator attraction. CONCLUSIONS Floral evolution occurred during the westward range expansion of parviflora, particularly in the zone of sympatry with xantiana. No evidence was found that strongly reduced flower size in sympatric parviflora (and RCD between parviflora and xantiana) is due to adaptation to limited pollinator availability. Rather, floral divergence appears to have been driven by other factors, such as interactions with congenerics in secondary sympatry.
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Affiliation(s)
| | - David A. Moeller
- Department of Plant Biology, University of Minnesota, 1445 Gortner Avenue, St Paul, MN 55108, USA
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