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Song B, Chen J, Lev-Yadun S, Niu Y, Gao Y, Ma R, Armbruster WS, Sun H. Multifunctionality of angiosperm floral bracts: a review. Biol Rev Camb Philos Soc 2024; 99:1100-1120. [PMID: 38291834 DOI: 10.1111/brv.13060] [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: 11/28/2022] [Revised: 01/02/2024] [Accepted: 01/22/2024] [Indexed: 02/01/2024]
Abstract
Floral bracts (bracteoles, cataphylls) are leaf-like organs that subtend flowers or inflorescences but are of non-floral origin; they occur in a wide diversity of species, representing multiple independent origins, and exhibit great variation in form and function. Although much attention has been paid to bracts over the past 150 years, our understanding of their adaptive significance remains remarkably incomplete. This is because most studies of bract function and evolution focus on only one or a few selective factors. It is widely recognised that bracts experience selection mediated by pollinators, particularly for enhancing pollinator attraction through strong visual, olfactory, or echo-acoustic contrast with the background and through signalling the presence of pollinator rewards, either honestly (providing rewards for pollinators), or deceptively (attraction without reward or even trapping pollinators). However, studies in recent decades have demonstrated that bract evolution is also affected by agents other than pollinators. Bracts can protect flowers, fruits, or seeds from herbivores by displaying warning signals, camouflaging conspicuous reproductive organs, or by providing physical barriers or toxic chemicals. Reviews of published studies show that bracts can also promote seed dispersal and ameliorate the effects of abiotic stressors, such as low temperature, strong ultraviolet radiation, heavy rain, drought, and/or mechanical abrasion, on reproductive organs or for the plants' pollinators. In addition, green bracts and greening of colourful bracts after pollination promote photosynthetic activity, providing substantial carbon (photosynthates) for fruit or seed development, especially late in a plant's life cycle or season, when leaves have started to senesce. A further layer of complexity derives from the fact that the agents of selection driving the evolution of bracts vary between species and even between different developmental stages within a species, and selection by one agent can be reinforced or opposed by other agents. In summary, our survey of the literature reveals that bracts are multifunctional and subject to multiple agents of selection. To understand fully the functional and evolutionary significance of bracts, it is necessary to consider multiple selection agents throughout the life of the plant, using integrative approaches to data collection and analysis.
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Affiliation(s)
- Bo Song
- Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
| | - Jiaqi Chen
- Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
- School of Life Sciences, Yunnan University, Huannan Road, East of University Town, Chenggong New Area, Kunming, 650500, China
| | - Simcha Lev-Yadun
- Department of Biology and Environment, Faculty of Natural Sciences, University of Haifa at Oranim, Kiryat Tiv'on, 36006, Israel
| | - Yang Niu
- Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
| | - Yongqian Gao
- Yunnan Forestry Technological College, 1 Jindian, Kunming, 650224, China
| | - Rong Ma
- Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
| | - W Scott Armbruster
- 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, PO Box 757000, Fairbanks, AK, 99775, USA
| | - Hang Sun
- Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
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Hou M, Opedal ØH, Zhao ZG. Sexually concordant selection on floral traits despite greater opportunity for selection through male fitness. THE NEW PHYTOLOGIST 2024; 241:926-936. [PMID: 37899633 DOI: 10.1111/nph.19370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 10/16/2023] [Indexed: 10/31/2023]
Abstract
Pollinators are important drivers of floral trait evolution, yet plant populations are not always perfectly adapted to their pollinators. Such apparent maladaptation may result from conflicting selection through male and female sexual functions in hermaphrodites. We studied sex-specific mating patterns and phenotypic selection on floral traits in Aconitum gymnandrum. After genotyping 1786 offspring, we partitioned individual fitness into sex-specific selfed and outcrossed components and estimated phenotypic selection acting through each. Relative fitness increased with increasing mate number, and more so for male function. This led to greater opportunity for selection through outcrossed male fitness, though patterns of phenotypic selection on floral traits tended to be similar, and with better support for selection through female rather than male fitness components. We detected directional selection through one or more fitness component for larger flower number, larger flowers, and more negative nectar gradients within inflorescences. Our results are consistent with Bateman's principles for sex-specific mating patterns and illustrate that, despite the expected difference in opportunity for selection, patterns of variation in selection across traits can be rather similar for the male and female sexual functions. These results shed new light on the effect of sexual selection on the evolution of floral traits.
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Affiliation(s)
- Meng Hou
- College of Ecology, Lanzhou University, 730000, Lanzhou, China
- Key Laboratory of Wetland Ecology and Environment, State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, 130102, Changchun, China
| | | | - Zhi-Gang Zhao
- College of Ecology, Lanzhou University, 730000, Lanzhou, China
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3
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van der Kooi CJ, Reuvers L, Spaethe J. Honesty, reliability, and information content of floral signals. iScience 2023; 26:107093. [PMID: 37426347 PMCID: PMC10329176 DOI: 10.1016/j.isci.2023.107093] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2023] Open
Abstract
Plants advertise their presence by displaying attractive flowers, which pollinators use to locate a floral reward. Understanding how floral traits scale with reward status lies at the heart of pollination biology, because it connects the different interests of plants and pollinators. Studies on plant phenotype-reward associations often use different terms and concepts, which limits developing a broader synthesis. Here, we present a framework with definitions of the key aspects of plant phenotype-reward associations and provide measures to quantify them across different species and studies. We first distinguish between cues and signals, which are often used interchangeably, but have different meanings and are subject to different selective pressures. We then define honesty, reliability, and information content of floral cues/signals and provide ways to quantify them. Finally, we discuss the ecological and evolutionary factors that determine flower phenotype-reward associations, how context-dependent and temporally variable they are, and highlight promising research directions.
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Affiliation(s)
- Casper J. van der Kooi
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
- Department of Behavioral Physiology and Sociobiology, University of Würzburg, Würzburg, Germany
| | - Lora Reuvers
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - Johannes Spaethe
- Department of Behavioral Physiology and Sociobiology, University of Würzburg, Würzburg, Germany
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4
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Rodríguez-Otero C, Hedrén M, Friberg M, Opedal ØH. Analysis of trait-performance-fitness relationships reveals pollinator-mediated selection on orchid pollination traits. AMERICAN JOURNAL OF BOTANY 2023:e16128. [PMID: 36655508 DOI: 10.1002/ajb2.16128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 07/24/2022] [Accepted: 08/01/2022] [Indexed: 06/17/2023]
Abstract
PREMISE The role of pollinators in evolutionary floral divergence has spurred substantial effort into measuring pollinator-mediated phenotypic selection and its variation in space and time. For such estimates, the fitness consequences of pollination processes must be separated from other factors affecting fitness. METHODS We built a fitness function linking phenotypic traits of food-deceptive orchids to female reproductive success by including pollinator visitation and pollen deposition as intermediate performance components and used the fitness function to estimate the strength of pollinator-mediated selection through female reproductive success. We also quantified male performance as pollinarium removal and assessed similarity in trait effects on male and female performance. RESULTS The proportion of plants visited at least once by an effective pollinator was moderate to high, ranging from 53.7% to 85.1%. Tall, many-flowered plants were often more likely to be visited and pollinated. Given effective pollination, pollen deposition onto stigmas tended to be more likely for taller plants. Pollen deposition further depended on traits affecting the physical fit of pollinators to flowers (flower size, spur length), though the exact relationships varied in time and space. Using the fitness function to assess pollinator-mediated selection through female reproductive success acting on multiple traits, we found that selection varied detectably among taxa after accounting for sampling uncertainty. Across taxa, selection on most traits was stronger on average and more variable when pollination was less reliable. CONCLUSIONS These results support pollination-related trait-performance-fitness relationships and thus pollinator-mediated selection on traits functionally involved in the pollination process.
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Affiliation(s)
| | - Mikael Hedrén
- Department of Biology, Biodiversity Unit, Lund University, SE, 22362, Lund, Sweden
| | - Magne Friberg
- Department of Biology, Biodiversity Unit, Lund University, SE, 22362, Lund, Sweden
| | - Øystein H Opedal
- Department of Biology, Biodiversity Unit, Lund University, SE, 22362, Lund, Sweden
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5
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Monroe JG, Cai H, Des Marais DL. Diversity in nonlinear responses to soil moisture shapes evolutionary constraints in Brachypodium. G3 (BETHESDA, MD.) 2021; 11:jkab334. [PMID: 34570202 PMCID: PMC8664479 DOI: 10.1093/g3journal/jkab334] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 09/15/2021] [Indexed: 12/03/2022]
Abstract
Water availability is perhaps the greatest environmental determinant of plant yield and fitness. However, our understanding of plant-water relations is limited because-like many studies of organism-environment interaction-it is primarily informed by experiments considering performance at two discrete levels-wet and dry-rather than as a continuously varying environmental gradient. Here, we used experimental and statistical methods based on function-valued traits to explore genetic variation in responses to a continuous soil moisture gradient in physiological and morphological traits among 10 genotypes across two species of the model grass genus Brachypodium. We find that most traits exhibit significant genetic variation and nonlinear responses to soil moisture variability. We also observe differences in the shape of these nonlinear responses between traits and genotypes. Emergent phenomena arise from this variation including changes in trait correlations and evolutionary constraints as a function of soil moisture. Our results point to the importance of considering diversity in nonlinear organism-environment relationships to understand plastic and evolutionary responses to changing climates.
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Affiliation(s)
- J Grey Monroe
- Department of Plant Sciences, University of California at Davis, Davis, CA 95616, USA
| | - Haoran Cai
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - David L Des Marais
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- The Arnold Arboretum of Harvard University, Boston, MA 02130, USA
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Pélabon C, Albertsen E, Rouzic AL, Firmat C, Bolstad GH, Armbruster WS, Hansen TF. Quantitative assessment of observed versus predicted responses to selection. Evolution 2021; 75:2217-2236. [PMID: 34137027 DOI: 10.1111/evo.14284] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 03/26/2021] [Accepted: 05/26/2021] [Indexed: 11/26/2022]
Abstract
Although artificial-selection experiments seem well suited to testing our ability to predict evolution, the correspondence between predicted and observed responses is often ambiguous due to the lack of uncertainty estimates. We present equations for assessing prediction error in direct and indirect responses to selection that integrate uncertainty in genetic parameters used for prediction and sampling effects during selection. Using these, we analyzed a selection experiment on floral traits replicated in two taxa of the Dalechampia scandens (Euphorbiaceae) species complex for which G-matrices were obtained from a diallel breeding design. After four episodes of bidirectional selection, direct and indirect responses remained within wide prediction intervals, but appeared different from the predictions. Combined analyses with structural-equation models confirmed that responses were asymmetrical and lower than predicted in both species. We show that genetic drift is likely to be a dominant source of uncertainty in typically-dimensioned selection experiments in plants and a major obstacle to predicting short-term evolutionary trajectories.
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Affiliation(s)
- Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Elena Albertsen
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway.,Norwegian Institute of Bioeconomy Research (NIBIO), Ås, Norway
| | - Arnaud Le Rouzic
- Évolution, Génomes, Comportement, Écologie, Université Paris-Saclay CNRS-IRD, Gif sur Yvette, France
| | - Cyril Firmat
- INRAE, Université de Toulouse, UMR AGIR, Castanet-Tolosan Cedex, France
| | - Geir H Bolstad
- Norwegian Institute for Nature Research (NINA), Trondheim, Norway
| | - W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth, UK.,Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, USA
| | - Thomas F Hansen
- Department of Biology, Centre for Ecological and Evolutionary Synthesis, University of Oslo, Oslo, Norway
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Essenberg CJ. Intraspecific relationships between floral signals and rewards with implications for plant fitness. AOB PLANTS 2021; 13:plab006. [PMID: 33708371 PMCID: PMC7937183 DOI: 10.1093/aobpla/plab006] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 01/11/2021] [Indexed: 06/12/2023]
Abstract
Within-species variation in traits such as petal size or colour often provides reliable information to pollinators about the rewards offered to them by flowers. In spite of potential disadvantages of allowing pollinators to discriminate against less-rewarding flowers, examples of informative floral signals are diverse in form and widely distributed across plant taxa, apparently having evolved repeatedly in different lineages. Although hypotheses about the adaptive value of providing reward information have been proposed and tested in a few cases, a unified effort to understand the evolutionary mechanisms favouring informative floral signals has yet to emerge. This review describes the diversity of ways in which floral signals can be linked with floral rewards within plant species and discusses the constraints and selective pressures on floral signal-reward relationships. It focuses particularly on how information about floral rewards can influence pollinator behaviour and how those behavioural changes may, in turn, affect plant fitness, selecting either for providing or withholding reward information. Most of the hypotheses about the evolution of floral signal-reward relationships are, as yet, untested, and the review identifies promising research directions for addressing these considerable gaps in knowledge. The advantages and disadvantages of sharing floral reward information with pollinators likely play an important role in floral trait evolution, and opportunities abound to further our understanding of this neglected aspect of floral signalling.
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8
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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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Opedal ØH, Albertsen E, Pérez-Barrales R, Armbruster WS, Pélabon C. No evidence that seed predators constrain pollinator-mediated trait evolution in a tropical vine. AMERICAN JOURNAL OF BOTANY 2019; 106:145-153. [PMID: 30625241 DOI: 10.1002/ajb2.1209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 10/15/2018] [Indexed: 06/09/2023]
Abstract
PREMISE OF THE STUDY Turnover in biotic communities across heterogeneous landscapes is expected to lead to variation in interactions among plants, their mutualists, and their antagonists. Across a fragmented landscape in northern Costa Rica, populations of the euphorb vine Dalechampia scandens vary widely in mating systems and associated blossom traits. Previous work suggested that populations are well adapted to the local reliability of pollination by apid and megachilid bees. We tested whether variation in the intensity of predispersal seed predation by seed weevils in the genus Nanobaris also contributes to the observed variation in blossom traits. METHODS We studied spatiotemporal variation in the relationships between floral advertisement and the probability of seed predation within three focal populations. Then we assessed among-population covariation of predation rate, pollination reliability, mating system, and blossom traits across 20 populations. KEY RESULTS The probability of seed predation was largely unrelated to variation in floral advertisement both within focal populations and among the larger sample of populations. The rate of seed predation was only weakly associated with the rate of cross-pollination (allogamy) in each population but tended to be proportionally greater in populations experiencing less reliable pollination. CONCLUSIONS These results suggest that geographic variation in the intensity of antagonistic interactions have had only minor modifying effects on the evolutionary trajectories of floral advertisement in plant populations in this system. Thus, pollinator-driven floral trait evolution in D. scandens in the study area appears not to be influenced by conflicting seed-predator-mediated selection.
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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
| | - Rocío Pérez-Barrales
- School of Biological Sciences, University of Portsmouth, King Henry Building, King Henry I Street, Portsmouth, PO1 2DY, UK
| | - W Scott Armbruster
- 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, Alaska, 99775, USA
| | - Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway
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10
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Xun E, Zhang Y, Zhao J, Guo J. Heavy metals in nectar modify behaviors of pollinators and nectar robbers: Consequences for plant fitness. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 242:1166-1175. [PMID: 30114599 DOI: 10.1016/j.envpol.2018.07.128] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 07/28/2018] [Accepted: 07/28/2018] [Indexed: 06/08/2023]
Abstract
Plants growing in heavy-metal-rich soils can accumulate metals into their nectar. Nectar chemical composition can alter foraging behavior of floral visitors (including pollinators and floral antagonists) and further affect plant reproductive fitness. The role of nectar heavy metals in deterring pollinators (e.g., shortening foraging time) has been recently studied, but their effects on plant reproduction via changes in behaviors of both pollinators and floral antagonists (e.g., nectar robbers) are less understood. We experimentally manipulated four nectar heavy metals (Zn, Cu, Ni, and Pb) in a native ornamental plant, Hosta ensata F. Maekawa, to investigate the effect of nectar metals on plant reproductive success. We also recorded nectar robbing as well as foraging time and visitation rate of pollinators to assess whether nectar metals could alter the behavior of antagonists and mutualists. Although metals in nectar had no significant direct effects on plant reproduction via hand-pollination, we detected their positive indirect effects on components of female fitness mediated by pollinators and nectar robbers. Matching effects on female plant fitness, nectar robbers responded negatively to the presence of metals in nectar, robbing metal-treated flowers less often. Pollinators spent less time foraging on metal-treated flowers, but their visitation rate to metal-treated flowers was significantly higher than to control flowers. Moreover, pollinators removed less nectar from flowers treated with metals. Our results provide the first direct evidence to date that heavy metals in nectar are capable of deterring nectar robbers and modifying pollinator foraging behavior to enhance plant reproductive fitness.
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Affiliation(s)
- Erna Xun
- Institute of Grassland Science, Northeast Normal University and Key Laboratory for Vegetation Ecology, Ministry of Education, Changchun, 130024, China
| | - Yanwen Zhang
- Institute of Grassland Science, Northeast Normal University and Key Laboratory for Vegetation Ecology, Ministry of Education, Changchun, 130024, China; Department of Biology, Changchun Normal University, Changchun, 130032, China; Department of Biology, Eastern Liaoning University, Dandong, 118003, China.
| | - Jimin Zhao
- Department of Biology, Changchun Normal University, Changchun, 130032, China
| | - Jixun Guo
- Institute of Grassland Science, Northeast Normal University and Key Laboratory for Vegetation Ecology, Ministry of Education, Changchun, 130024, China
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11
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Abstract
Plants can send floral signals to advertise their reward for pollinators. Based on the presence or absents of such signals, pollinators can determine whether to visit plants. Plants can send dishonest signals but foraging behaviours of pollinators can limit the cheating strategies of plants. We model the plant-pollinator interactions by the two-type Spence signalling game and investigate the conditions under which honest signalling can be established. In our model, plants either send costly signal or they do not. The cost of signal is dependent on the quality of plant. Pollinators can learn from the interactions with plants and can update their willingness to visit plants’ flowers to maximize their foraging efficiency. We find three general conditions that are required for the evolutionary stability of honest signaling. Those conditions are satisfied if there is (a) a high frequency of high-yield signalling plants in the population, (b) the balance between cost and benefit of signalling, and (c) high cost of dishonest signalling. Our model also predicts that other factors contributing to the establishment of honest signaling are the low abundance of pollinators, and the positive density-dependent and positive frequency-dependent relationship between plants and pollinators.
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12
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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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13
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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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14
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Sun SG, Armbruster WS, Huang SQ. Geographic consistency and variation in conflicting selection generated by pollinators and seed predators. ANNALS OF BOTANY 2016; 118:227-37. [PMID: 27325896 PMCID: PMC4970362 DOI: 10.1093/aob/mcw097] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 04/05/2016] [Indexed: 05/13/2023]
Abstract
BACKGROUNDS AND AIMS Floral traits that attract pollinators may also attract seed predators, which, in turn, may generate conflicting natural selection on such traits. Although such selection trade-offs are expected to vary geographically, few studies have investigated selection mediated by pollinators and seed predators across a geographic mosaic of environments and floral variation. METHODS Floral traits were investigated in 14 populations of the bumble-bee-pollinated herb, Pedicularis rex, in which tubular flowers are subtended by cupular bracts holding rain water. To study potentially conflicting selection on floral traits generated by pollinators and florivores, stigmatic pollen loads, initial seed set, pre-dispersal seed predation and final viable seed production were measured in 12-14 populations in the field. KEY RESULTS Generalized Linear Model (GLM) analyses indicated that the pollen load on stigmas was positively related to the exsertion of the corolla beyond the cupular bracts and size of the lower corolla lip, but so too was the rate of seed predation, creating conflicting selection on both floral traits. A geographic mosaic of selection mediated by seed predators, but not pollinators, was indicated by significant variation in levels of seed predation and the inclusion of two-, three- and four-way interaction terms between population and seed predation in the best model [lowest corrected Akaike Information Criterion (AICc)] explaining final seed production. CONCLUSIONS These results indicate opposing selection in operation: pollinators generated selection for greater floral exsertion beyond the bracts, but seed predators generated selection for reduced exsertion above the protective pools of water, although the strength of the latter varied across populations.
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Affiliation(s)
- Shi-Guo Sun
- School of Life Sciences, Central China Normal University, Wuhan 430079, China
| | - 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
| | - Shuang-Quan Huang
- School of Life Sciences, Central China Normal University, Wuhan 430079, China
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Bailes EJ, Ollerton J, Pattrick JG, Glover BJ. How can an understanding of plant-pollinator interactions contribute to global food security? CURRENT OPINION IN PLANT BIOLOGY 2015; 26:72-79. [PMID: 26116979 DOI: 10.1016/j.pbi.2015.06.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 04/29/2015] [Accepted: 06/01/2015] [Indexed: 06/04/2023]
Abstract
Pollination of crops by animals is an essential part of global food production, but evidence suggests that wild pollinator populations may be declining while a number of problems are besetting managed honey bee colonies. Animal-pollinated crops grown today, bred in an environment where pollination was less likely to limit fruit set, are often suboptimal in attracting and sustaining their pollinator populations. Research into plant-pollinator interactions is often conducted in a curiosity-driven, ecological framework, but may inform breeding and biotechnological approaches to enhance pollinator attraction and crop yield. In this article we review key topics in current plant-pollinator research that have potential roles in future crop breeding for enhanced global food security.
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Affiliation(s)
- Emily J Bailes
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Jeff Ollerton
- Department of Environmental and Geographic Sciences, University of Northampton, Avenue Campus, Northampton NN2 6JD, UK
| | - Jonathan G Pattrick
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Beverley J Glover
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
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Le Rouzic A, Hansen TF, Gosden TP, Svensson EI. Evolutionary Time-Series Analysis Reveals the Signature of Frequency-Dependent Selection on a Female Mating Polymorphism. Am Nat 2015; 185:E182-96. [DOI: 10.1086/680982] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Pélabon C, Hennet L, Strimbeck R, Johnson H, Armbruster WS. Blossom colour change after pollination provides carbon for developing seeds. Funct Ecol 2015. [DOI: 10.1111/1365-2435.12427] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology Norwegian University of Science and Technology Trondheim 7491 Norway
| | - Lauriane Hennet
- Centre for Biodiversity Dynamics, Department of Biology Norwegian University of Science and Technology Trondheim 7491 Norway
| | - Richard Strimbeck
- Department of Biology Norwegian University of Science and Technology Trondheim 7491 Norway
| | - Hansen Johnson
- Department of Biology Norwegian University of Science and Technology Trondheim 7491 Norway
| | - W. Scott Armbruster
- Department of Biology Norwegian University of Science and Technology Trondheim 7491 Norway
- School of Biological Sciences University of Portsmouth Portsmouth PO1 2DY UK
- Institute of Arctic Biology University of Alaska Fairbanks AK 99775 USA
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Bolstad GH, Hansen TF, Pélabon C, Falahati-Anbaran M, Pérez-Barrales R, Armbruster WS. Genetic constraints predict evolutionary divergence in Dalechampia blossoms. Philos Trans R Soc Lond B Biol Sci 2015; 369:20130255. [PMID: 25002700 PMCID: PMC4084540 DOI: 10.1098/rstb.2013.0255] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
If genetic constraints are important, then rates and direction of evolution should be related to trait evolvability. Here we use recently developed measures of evolvability to test the genetic constraint hypothesis with quantitative genetic data on floral morphology from the Neotropical vine Dalechampia scandens (Euphorbiaceae). These measures were compared against rates of evolution and patterns of divergence among 24 populations in two species in the D. scandens species complex. We found clear evidence for genetic constraints, particularly among traits that were tightly phenotypically integrated. This relationship between evolvability and evolutionary divergence is puzzling, because the estimated evolvabilities seem too large to constitute real constraints. We suggest that this paradox can be explained by a combination of weak stabilizing selection around moving adaptive optima and small realized evolvabilities relative to the observed additive genetic variance.
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Affiliation(s)
- Geir H Bolstad
- Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Thomas F Hansen
- Department of Biology, Centre for Ecological and Evolutionary Synthesis, University of Oslo, 0316 Oslo, Norway
| | - Christophe Pélabon
- Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Mohsen Falahati-Anbaran
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway School of Biology and Center of Excellence in Phylogeny of Living Organisms, University of Tehran, 14155-6455 Tehran, Iran
| | | | - W Scott Armbruster
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK Institute of Arctic Biology, University of Alaska, Fairbanks AK 99775, USA
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20
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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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Howard AF, Barrows EM. Self-pollination rate and floral-display size in Asclepias syriaca (Common Milkweed) with regard to floral-visitor taxa. BMC Evol Biol 2014; 14:144. [PMID: 24958132 PMCID: PMC4080991 DOI: 10.1186/1471-2148-14-144] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 05/20/2014] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Animals fertilize thousands of angiosperm species whose floral-display sizes can significantly influence pollinator behavior and plant reproductive success. Many studies have measured the interactions among pollinator behavior, floral-display size, and plant reproductive success, but few studies have been able to separate the effects of pollinator behavior and post-pollination processes on angiosperm sexual reproduction. In this study, we utilized the highly self-incompatible pollinium-pollination system of Asclepias syriaca (Common Milkweed) to quantify how insect visitors influenced male reproductive success measured as pollen removal, female reproductive success measured as pollen deposition, and self-pollination rate. We also determined how floral-display size impacts both visitor behavior and self-pollination rate. RESULTS Four insect taxonomic orders visited A. syriaca: Coleoptera, Diptera, Hymenoptera, and Lepidoptera. We focused on three groups of visitor taxa within two orders (Hymenoptera and Lepidoptera) with sample sizes large enough for quantitative analysis: Apis mellifera (Western Honey Bee), Bombus spp. (bumble bees) and lepidopterans (butterflies and moths). Qualitatively, lepidopterans had the highest pollinator importance values, but the large variability in the lepidopteran data precluded meaningful interpretation of much of their behavior. The introduced A. mellifera was the most effective and most important diurnal pollinator with regard to both pollen removal and pollen deposition. However, when considering the self-incompatibility of A. syriaca, A. mellifera was not the most important pollinator because of its high self-pollination rate as compared to Bombus spp. Additionally, the rate of self-pollination increased more rapidly with the number of flowers per inflorescence in A. mellifera than in the native Bombus spp. CONCLUSIONS Apis mellifera's high rate of self-pollination may have significant negative effects on both male and female reproductive successes in A. syriaca, causing different selection on floral-display size than native pollinators.
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Affiliation(s)
- Aaron F Howard
- Department of Biology, Georgetown University, Box 571229, Washington, DC 20057-1229, USA
| | - Edward M Barrows
- Department of Biology, Georgetown University, Box 571229, Washington, DC 20057-1229, USA
- Center for the Environment, Georgetown University, Box 571229, Washington, DC 20057-1229, USA
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22
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Renoult JP, Thomann M, Schaefer HM, Cheptou PO. Selection on quantitative colour variation in Centaurea cyanus: the role of the pollinator's visual system. J Evol Biol 2013; 26:2415-27. [PMID: 24070120 DOI: 10.1111/jeb.12234] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 07/16/2013] [Accepted: 07/29/2013] [Indexed: 11/29/2022]
Abstract
Even though the importance of selection for trait evolution is well established, we still lack a functional understanding of the mechanisms underlying phenotypic selection. Because animals necessarily use their sensory system to perceive phenotypic traits, the model of sensory bias assumes that sensory systems are the main determinant of signal evolution. Yet, it has remained poorly known how sensory systems contribute to shaping the fitness surface of selected individuals. In a greenhouse experiment, we quantified the strength and direction of selection on floral coloration in a population of cornflowers exposed to bumblebees as unique pollinators during 4 days. We detected significant selection on the chromatic and achromatic (brightness) components of floral coloration. We then studied whether these patterns of selection are explicable by accounting for the visual system of the pollinators. Using data on bumblebee colour vision, we first showed that bumblebees should discriminate among quantitative colour variants. The observed selection was then compared to the selection predicted by psychophysical models of bumblebee colour vision. The achromatic but not the chromatic channel of the bumblebee's visual system could explain the observed pattern of selection. These results highlight that (i) pollinators can select quantitative variation in floral coloration and could thus account for a gradual evolution of flower coloration, and (ii) stimulation of the visual system represents, at least partly, a functional mechanism potentially explaining pollinators' selection on floral colour variants.
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Affiliation(s)
- J P Renoult
- Department of Evolutionary Biology and Animal Ecology, Faculty of Biology, University of Freiburg, Freiburg, Germany
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23
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Falahati-Anbaran M, Stenøien HK, Pélabon C, Bolstad GH, Perez-Barrales R, Hansen TF, Armbruster WS. Development of microsatellite markers for the neotropical vine Dalechampia scandens (Euphorbiaceae). APPLICATIONS IN PLANT SCIENCES 2013; 1:apps1200492. [PMID: 25202553 PMCID: PMC4105026 DOI: 10.3732/apps.1200492] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 11/16/2012] [Indexed: 06/03/2023]
Abstract
PREMISE OF THE STUDY Microsatellite markers were developed to assess polymorphism and level of genetic diversity in four Mexican populations of the neotropical vine Dalechampia scandens (Euphorbiaceae). • METHODS AND RESULTS Thirty-seven microsatellite markers representing bi-, tri-, tetra-, and pentanucleotide microsatellite repeats were developed. In total, 166 alleles were identified across 54 individuals. The number of alleles varied from one to 11 with an average of 4.49 alleles per locus. All loci except one were highly polymorphic between populations, whereas considerably less variation was detected within populations for most loci. The average observed and expected heterozygosities across study populations ranged from 0 to 0.63 and 0 to 0.59, respectively, for individual loci, and a deviation from Hardy-Weinberg equilibrium was observed for most loci. • CONCLUSIONS The developed markers may be useful for studying genetic structure, parentage analysis, mapping, phylogeography, and cross-amplification in other closely related species of Dalechampia.
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Affiliation(s)
- Mohsen Falahati-Anbaran
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Hans K. Stenøien
- Museum of Natural History and Archaeology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Geir H. Bolstad
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Rocio Perez-Barrales
- Plant Biology and Ecology Department, University of Seville, 41080 Seville, Spain
- 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, P.O. Box 1066, N-0316 Oslo, Norway
| | - W. Scott Armbruster
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska 99775 USA
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Pélabon C, Bolstad GH, Egset CK, Cheverud JM, Pavlicev M, Rosenqvist G. On the relationship between ontogenetic and static allometry. Am Nat 2013; 181:195-212. [PMID: 23348774 DOI: 10.1086/668820] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Ontogenetic and static allometries describe how a character changes in size when the size of the organism changes during ontogeny and among individuals measured at the same developmental stage, respectively. Understanding the relationship between these two types of allometry is crucial to understanding the evolution of allometry and, more generally, the evolution of shape. However, the effects of ontogenetic allometry on static allometry remain largely unexplored. Here, we first show analytically how individual variation in ontogenetic allometry and body size affect static allometry. Using two longitudinal data sets on ontogenetic and static allometry, we then estimate variances and covariances for the different parameters of the ontogenetic allometry defined in our model and assess their relative contribution to the static allometric slope. The mean ontogenetic allometry is the main parameter that determines the static allometric slope, while the covariance between the ontogenetic allometric slope and body size generates most of the discrepancies between ontogenetic and static allometry. These results suggest that the apparent evolutionary stasis of the static allometric slope is not generated by internal (developmental) constraints but more likely results from external constraints imposed by selection.
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Affiliation(s)
- Christophe Pélabon
- Centre for Conservation Biology, Department of Biology, University of Science and Technology NTNU, 7491 Trondheim, Norway.
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Matsumura S, Arlinghaus R, Dieckmann U. Standardizing Selection Strengths to Study Selection in the Wild: A Critical Comparison and Suggestions for the Future. Bioscience 2012. [DOI: 10.1525/bio.2012.62.12.6] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Bolstad GH, Pélabon C, Larsen LK, Fleming IA, Viken A, Rosenqvist G. The effect of purging on sexually selected traits through antagonistic pleiotropy with survival. Ecol Evol 2012; 2:1181-94. [PMID: 22833793 PMCID: PMC3402193 DOI: 10.1002/ece3.246] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 02/24/2012] [Accepted: 02/24/2012] [Indexed: 11/21/2022] Open
Abstract
Sexually selected traits are expected to evolve to a point where their positive effect on reproductive success is counterbalanced by their negative effect on survival. At the genetic level, such a trade-off implies antagonistic pleiotropy between survival and the expression of sexually selected traits. Yet, the consequences of such a genetic architecture have been largely overlooked in studies examining how inbreeding influences sexually selected traits. These studies have solely interpreted their results as an effect of increased homozygosity. An alternative, however, is that purging of recessive alleles deleterious for survival when inbreeding increases can negatively affect the expression of sexually selected traits through antagonistic pleiotropy. We tested this hypothesis by analyzing the effects of inbreeding on several male ornaments and life-history traits across 20 captive populations of guppies (Poecilia reticulata) with varying levels of inbreeding. Only one ornament, orange area, decreased in its expression with an increasing level of inbreeding. This was most likely due to purging because we found no within-population relationship between orange area and the inbreeding coefficient. We further tested this hypothesis by crossing unrelated individuals from the four most inbred populations, creating a group of individuals with purged genomes but restored heterozygosity. Restoration of heterozygosity only slightly increased orange area, confirming that the decrease in orange area in the inbred populations most likely resulted from purging. These results support previous studies suggesting the existence of antagonistic pleiotropy between ornament expression and survival.
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Pélabon C, Thöne P, Hansen TF, Armbruster WS. Signal honesty and cost of pollinator rewards in Dalechampia scandens (Euphorbiaceae). ANNALS OF BOTANY 2012; 109:1331-40. [PMID: 22628366 PMCID: PMC3359932 DOI: 10.1093/aob/mcs091] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 02/23/2012] [Indexed: 05/16/2023]
Abstract
BACKGROUND AND AIMS Most species of Dalechampia vines (Euphorbiaceae) attract bee pollinators with terpenoid resins secreted by a gland-like structure in the inflorescence. In some species, pollinating bees appear to preferentially visit inflorescences (blossoms) with large resin-producing glands, whereas in other species bees preferentially visit blossoms with large involucral bracts. In this study, the reliability of bract and gland size as signals of the quantity of resin produced in one species, D. scandens, was assessed. Whether resin secretion has a cost with respect to the number or mass of the seeds produced by a blossom was also examined. METHODS Measurements were made of bract size, gland size and the amount of resin secreted by blossoms of D. scandens maintained in a common environment, and the relationships between these traits were analysed. Resin production was also manipulated, and the effects of the manipulation were tested on seed set and seed mass. KEY RESULTS The amount of resin produced was better predicted by the size of the gland than by the size of the bract. Furthermore, when the effect of gland size was accounted for, bract size only weakly predicted the amount of resin produced. Neither an increase in resin secretion (by daily removal of the resin) nor a decrease (by removal of the resin gland) affected seed set or seed mass detectably, but resin production correlated positively with mean seed mass at the individual level once the size of the resin gland was accounted for. CONCLUSIONS Gland size is a better indicator of the amount of reward than bract size, although the latter remained an honest signal of the quantity of resin produced. Resin secretion has no detectable cost in terms of seed production, but may be condition dependent, as suggested by a positive correlation with seed mass at the individual level.
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Affiliation(s)
- Christophe Pélabon
- Centre for Conservation Biology, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway.
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Adler LS, Irwin RE. Nectar alkaloids decrease pollination and female reproduction in a native plant. Oecologia 2011; 168:1033-41. [DOI: 10.1007/s00442-011-2153-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 09/22/2011] [Indexed: 11/30/2022]
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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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Sapir Y, Armbruster WS. Pollinator-mediated selection and floral evolution: from pollination ecology to macroevolution. THE NEW PHYTOLOGIST 2010; 188:303-306. [PMID: 20941844 DOI: 10.1111/j.1469-8137.2010.03467.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Affiliation(s)
- Yuval Sapir
- The Botanical Garden, Department of Plant Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel.
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