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Zhao J, Li Y, Wang X, Li M, Yu W, Chen J, Zhang L. Parasite-host network analysis provides insights into the evolution of two mistletoe lineages (Loranthaceae and Santalaceae). PLANT DIVERSITY 2023; 45:702-711. [PMID: 38197012 PMCID: PMC10772182 DOI: 10.1016/j.pld.2023.03.008] [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: 11/14/2022] [Revised: 03/20/2023] [Accepted: 03/26/2023] [Indexed: 01/11/2024]
Abstract
Mistletoes are ecologically important parasitic plants, with > 1600 species from five lineages worldwide. Mistletoe lineages exhibit distinct patterns of species diversification and host specificity, however, the mechanisms underlying these differences are poorly understood. In this study, we analysed a comprehensive parasite-host network, including 280 host species from 60 families and 22 mistletoe species from two lineages (Santalaceae and Loranthaceae) in Xishuangbanna, located in a biodiversity hotspot of tropical Asia. We identified the factors that predict the infection strength of mistletoes. We also detected host specificity and the phylogenetic signal of mistletoes and their hosts. We found that this interaction network could be largely explained by a model based on the relative abundance of species. Host infection was positively correlated with diameter at breast height and tree coverage, but negatively correlated with wood density. Overall, closely related mistletoe species tend to interact more often with similar hosts. However, the two lineages showed a significantly different network pattern. Rates of host generality were higher in Loranthaceae than in Santalaceae, although neither lineage showed phylogenetic signal for host generality. This study demonstrates that the neutral interaction hypothesis provides suitable predictions of the mistletoe-host interaction network, and mistletoe species show significant phylogenetic signals for their hosts. Our findings also indicate that high species diversification in Loranthaceae may be explained by high rates of host generality and the evolutionary history shared by Loranthaceae species with diverse host plants in the tropics.
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Affiliation(s)
- Jin Zhao
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, Yunnan, China
- Engineering Research Center of Eco-environment in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang 443002, Hubei, China
| | - Yuanjie Li
- Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
| | - Xuanni Wang
- Linnaeus Labs Technology Co., Ltd, Wuyuan 333200, Jiangxi, China
| | - Manru Li
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, Yunnan, China
- Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
| | - Wenbin Yu
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, Yunnan, China
| | - Jin Chen
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, Yunnan, China
| | - Ling Zhang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, Yunnan, China
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2
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Medina M, Baker DM, Baltrus DA, Bennett GM, Cardini U, Correa AMS, Degnan SM, Christa G, Kim E, Li J, Nash DR, Marzinelli E, Nishiguchi M, Prada C, Roth MS, Saha M, Smith CI, Theis KR, Zaneveld J. Grand Challenges in Coevolution. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2021.618251] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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3
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Hollens-Kuhr H, van der Niet T, Cozien R, Kuhlmann M. Pollinator Community Predicts Trait Matching between Oil-Producing Flowers and a Guild of Oil-Collecting Bees. Am Nat 2021; 198:750-758. [PMID: 34762568 DOI: 10.1086/717050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractThe impact of pollinator community diversity on trait matching in plant-pollinator interactions is poorly studied, even though many mutualisms involve multiple interaction partners. We studied 10 communities in which one to three species of oil-collecting Rediviva bees pollinate the long-spurred, oil-producing flowers of Diascia "floribunda" to examine how pollinator diversity affects covariation of functional traits across sites and trait matching within sites. Floral spur length was significantly correlated with weighted grand mean foreleg length of the local bee community but not with foreleg length of individual bee species. The closeness of trait matching varied among populations and was inversely related to pollinator community diversity. For all bee species, trait matching was closest at sites characterized by exclusive pairwise interactions. Reduced trait matching associated with increased community diversity for individual pollinator species but close matching at the community level supports the importance of community context for shaping interacting traits of flowers and pollinators.
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4
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Van Goor J, Piatscheck F, Houston DD, Nason JD. Differential effects of nematode infection on pollinating and non-pollinating fig wasps: Can shared antagonism provide net benefits to a mutualism? J Anim Ecol 2021; 90:1764-1775. [PMID: 33934356 DOI: 10.1111/1365-2656.13495] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 04/01/2021] [Indexed: 01/12/2023]
Abstract
Species pairs that form mutualistic associations are also components of broader organismal community networks. These interaction networks have shaped the evolution of individual mutualisms through interspecific interactions ranging from secondarily mutualistic to intensely antagonistic. Our understanding of this complex context remains limited because characterizing the impacts of species interacting with focal mutualists is often difficult. How is the fitness of mutualists impacted by the co-occurring interactive network of community associates? We investigated this context using a model interaction network comprised of a fig and fig wasp mutualist, eight non-pollinating fig wasp (NPFW) antagonists/commensals and a nematode previously believed to be associated only with the pollinator wasp mutualist. Through repeated sampling and field observations, we characterized the ecological roles of these mutualist-associated organisms to identify key antagonists. We then investigated how potential nematode infection of NPFWs could impact wasp survival across key life stages and, in turn, inferred how this influences the fitness of the fig-pollinator mutualists. Unexpectedly, we found all Ficus petiolaris-associated NPFWs to be the targets for nematode infection, with infection levels sometimes exceeding that of pollinators. Experimental data collected for the most abundant NPFW species suggest that nematode infection significantly reduces their longevity. Further, comparisons of nematode loads for emerging and successfully arriving NPFWs suggest that infection severely limits their dispersal ability. Through these observations, we conclude that this infection could impact NPFWs more severely than either mutualistic partner, suggesting a novel role of density-dependent facultative mutualism between figs, pollinator wasps and the nematode. This antagonist-mediated suppression of other network antagonists may present an ecologically common mechanism through which antagonists can present net benefits for mutualists' fitness.
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Affiliation(s)
- Justin Van Goor
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA.,Department of Biology, University of Maryland College Park, College Park, MD, USA
| | - Finn Piatscheck
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA.,Smithsonian Tropical Research Institute, Panamá, República de Panamá
| | - Derek D Houston
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA.,Department of Natural and Environmental Sciences, Western Colorado University, Gunnison, CO, USA
| | - John D Nason
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA
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5
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de Medeiros BAS, Farrell BD. Evaluating insect-host interactions as a driver of species divergence in palm flower weevils. Commun Biol 2020; 3:749. [PMID: 33299067 PMCID: PMC7726107 DOI: 10.1038/s42003-020-01482-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 11/10/2020] [Indexed: 01/01/2023] Open
Abstract
Plants and their specialized flower visitors provide valuable insights into the evolutionary consequences of species interactions. In particular, antagonistic interactions between insects and plants have often been invoked as a major driver of diversification. Here we use a tropical community of palms and their specialized insect flower visitors to test whether antagonisms lead to higher population divergence. Interactions between palms and the insects visiting their flowers range from brood pollination to florivory and commensalism, with the latter being species that feed on decaying-and presumably undefended-plant tissues. We test the role of insect-host interactions in the early stages of diversification of nine species of beetles sharing host plants and geographical ranges by first delimiting cryptic species and then using models of genetic isolation by environment. The degree to which insect populations are structured by the genetic divergence of plant populations varies. A hierarchical model reveals that this variation is largely uncorrelated with the kind of interaction, showing that antagonistic interactions are not associated with higher genetic differentiation. Other aspects of host use that affect plant-associated insects regardless of the outcomes of their interactions, such as sensory biases, are likely more general drivers of insect population divergence.
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Affiliation(s)
- Bruno A S de Medeiros
- Smithsonian Tropical Research Institute, Panama City, Panama.
- Museum of Comparative Zoology, Department of Organismic & Evolutionary Biology, Harvard University, Cambridge, MA, USA.
| | - Brian D Farrell
- Museum of Comparative Zoology, Department of Organismic & Evolutionary Biology, Harvard University, Cambridge, MA, USA
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6
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Mathis KA, Bronstein JL. Our Current Understanding of Commensalism. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-011720-040844] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Commensalisms, interactions between two species in which one species benefits and the other experiences no net effect, are frequently mentioned in the ecological literature but are surprisingly little studied. Here we review and synthesize our limited understanding of commensalism. We then argue that commensalism is not a single type of interaction; rather, it is a suite of phenomena associated with distinct ecological processes and evolutionary consequences. For each form of commensalism we define, we present evidence for how, where, and why it occurs, including when it is evolutionarily persistent and when it is an occasional outcome of interactions that are usually mutualistic or antagonistic. We argue that commensalism should be of great interest in the study of species interactions due to its location at the center of the continuum between positive and negative outcomes. Finally, we offer a roadmap for future research.
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Affiliation(s)
- Kaitlyn A. Mathis
- Department of Biology, Clark University, Worcester, Massachusetts 01610, USA
| | - Judith L. Bronstein
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA
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7
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Adroit B, Zhuang X, Wappler T, Terral JF, Wang B. A case of long-term herbivory: specialized feeding trace on Parrotia (Hamamelidaceae) plant species. ROYAL SOCIETY OPEN SCIENCE 2020; 7:201449. [PMID: 33204482 PMCID: PMC7657907 DOI: 10.1098/rsos.201449] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 09/25/2020] [Indexed: 06/06/2023]
Abstract
Interactions between plants and insects evolved during millions of years of coevolution and maintain the trophic balance of terrestrial ecosystems. Documenting insect damage types (DT) on fossil leaves is essential for understanding the evolution of plant-insect interactions and for understanding the effects of major environmental changes on ecosystem structure. However, research focusing on palaeoherbivory is still sparse and only a tiny fraction of fossil leaf collections have been analysed. This study documents a type of insect damage found exclusively on the leaves of Parrotia species (Hamamelidaceae). This DT was identified on Parrotia leaves from Willershausen (Germany, Pliocene) and from Shanwang (China, Miocene) and on their respective endemic modern relatives: Parrotia perisca in the Hyrcanian forests (Iran) and Parrotia subaequalis in the Yixing forest (China). Our study demonstrates that this insect DT persisted over at least 15 Myr spanning eastern Asia to western Europe. Against expectations, more examples of this type of herbivory were identified on the fossil leaves than on the modern examples. This mismatch may suggest a decline of this specialized plant-insect interaction owing to the contraction of Parrotia populations in Eurasia during the late Cenozoic. However, the continuous presence of this DT demonstrates a robust and long-term plant-herbivore association, and provides new evidence for a shared biogeographic history of the two host plants.
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Affiliation(s)
- Benjamin Adroit
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, People's Republic of China
| | - Xin Zhuang
- College of Life Sciences, Nanjing University, 22 Hankou Road, Nanjing 210093, People's Republic of China
| | | | - Jean-Frederic Terral
- Institut des Sciences de l'Evolution, UMR5554 Université de Montpellier, CNRS, IRD, EPHE, Place Eugène Bataillon, 34095 Montpellier cedex 05, France
| | - Bo Wang
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, People's Republic of China
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8
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Cornwell BH. Gene flow in the anemone
Anthopleura elegantissima
limits signatures of local adaptation across an extensive geographic range. Mol Ecol 2020; 29:2550-2566. [DOI: 10.1111/mec.15506] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 05/22/2020] [Accepted: 06/01/2020] [Indexed: 02/06/2023]
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9
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Villacañas de Castro C, Hoffmeister TS. Friend or foe? A parasitic wasp shifts the cost/benefit ratio in a nursery pollination system impacting plant fitness. Ecol Evol 2020; 10:4220-4232. [PMID: 32489591 PMCID: PMC7246216 DOI: 10.1002/ece3.6190] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 01/16/2020] [Accepted: 02/17/2020] [Indexed: 11/26/2022] Open
Abstract
Nursery pollination systems are species interactions where pollinators also act as fruit/seed herbivores of the plant partner. While the plants depend on associated insects for pollination, the insects depend on the plants' reproductive structures for larval development. The outcome of these interactions is thus placed on a gradient between mutualism and antagonism. Less specialized interactions may fluctuate along this gradient with the ecological context, where natural enemies can play an important role. We studied whether a natural enemy may impact the level of seed consumption of a nursery pollinator and how this in turn may influence individual plant fitness. We used the plant Silene latifolia, its herbivore Hadena bicruris, and its ectoparasitoid Bracon variator as a model plant-herbivore-natural enemy system. We investigated seed output, germination, survival, and flower production as proxies for individual plant fitness. We show that B. variator decreases the level of seed consumption by H. bicruris larvae which in turn increased seed output in S. latifolia plants, suggesting that parasitism by B. variator may act as a regulator in the system. However, our results also show that plant survival and flower production decrease with higher seed densities, and therefore, an increase in seed output may be less beneficial for plant fitness than estimated from seed output alone. Our study should add another layer to the complex discussion of whether parasitoids contribute to plant fitness, as we show that taking simple proxies such as seed output is insufficient to determine the net effect of multitrophic interactions.
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Affiliation(s)
| | - Thomas S. Hoffmeister
- Population and Evolutionary Ecology GroupInstitute of EcologyFB 02University of BremenBremenGermany
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10
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Sun BF, Wang RW. Foundress numbers and the timing of selective events during interactions between figs and fig wasps. Sci Rep 2019; 9:3420. [PMID: 30833578 PMCID: PMC6399315 DOI: 10.1038/s41598-018-37498-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 12/07/2018] [Indexed: 11/09/2022] Open
Abstract
In intimate mutualisms between hosts and symbionts, selection can act repeatedly over the development times of the interacting individuals. Although much is now known about the overall ecological conditions that favor the evolution of mutualism, a current challenge is to understand how natural selection acts on the number and kinds of partners to shape the evolution and stability of these interactions. Using the obligate fig-fig wasp mutualism, our experiments showed that the proportion of figs developed to maturity increased quickly to 1.0 as the number of foundresses increased, regardless of whether the foundresses carried pollen. Selection against pollen-free wasps did not occur at this early stage in fig development. Within figs that developed, the proportion of galls producing adult wasps remained high as the number of pollen-carrying foundresses increases. In contrast, the proportion of galls producing adult wasps decreased as the number of pollen-free foundresses increased. Viable seed production increased as the number or proportion of pollen-carrying foundresses increased, but the average number of wasp offspring per pollen-carrying foundress was highest when she was the sole foundress. These results show that figs and their pollinator wasps differ in how fitness effects are distributed throughout the development of the interaction and depend on the number and proportion of pollen-carrying foundresses contributing to the interaction. These results suggest that temporal fluctuations in the local number and proportion of pollen-carrying wasps available to enter figs are likely to have strong but different effects on the figs and the wasps.
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Affiliation(s)
- Bao-Fa Sun
- Center for Ecological and Environmental Sciences, Institute of Medical Research, Northwestern Polytechnical University, Xi'an, 710072, China. .,CAS Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Rui-Wu Wang
- Center for Ecological and Environmental Sciences, Institute of Medical Research, Northwestern Polytechnical University, Xi'an, 710072, China.
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11
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Extreme diversification of floral volatiles within and among species of Lithophragma (Saxifragaceae). Proc Natl Acad Sci U S A 2019; 116:4406-4415. [PMID: 30765532 DOI: 10.1073/pnas.1809007116] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
A major challenge in evolutionary biology is to understand how complex traits of multiple functions have diversified and codiversified across interacting lineages and geographic ranges. We evaluate intra- and interspecific variation in floral scent, which is a complex trait of documented importance for mutualistic and antagonistic interactions between plants, pollinators, and herbivores. We performed a large-scale, phylogenetically structured study of an entire plant genus (Lithophragma, Saxifragaceae), of which several species are coevolving with specialized pollinating floral parasites of the moth genus Greya (Prodoxidae). We sampled 94 Lithophragma populations distributed across all 12 recognized Lithophragma species and subspecies, and four populations of related saxifragaceous species. Our results reveal an unusually high diversity of floral volatiles among populations, species, and clades within the genus. Moreover, we found unexpectedly major changes at each of these levels in the biosynthetic pathways used by local populations in their floral scents. Finally, we detected significant, but variable, genus- and species-level patterns of ecological convergence in the floral scent signal, including an impact of the presence and absence of two pollinating Greya moth species. We propose that one potential key to understanding floral scent variation in this hypervariable genus is its geographically diverse interactions with the obligate specialized Greya moths and, in some species and sites, more generalized copollinators.
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12
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Interaction strength promotes robustness against cascading effects in mutualistic networks. Sci Rep 2019; 9:676. [PMID: 30679559 PMCID: PMC6345762 DOI: 10.1038/s41598-018-35803-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 07/25/2018] [Indexed: 11/08/2022] Open
Abstract
Perturbations, such as fluctuations in abundance, can ripple across species assemblages through ecological interactions. Furthermore, the way in which ecological interactions are organized into a network and the interaction strengths connecting species may be important for cascading effects. Previous work revealed that network structure determines how cascading effects spread across species assemblages. A next step is to understand how interaction strengths influence cascading effects. Here, we assume that perturbations have negative effects, and we evaluate whether interaction strength affects network robustness to cascading effects in mutualistic interactions, and examine the role of network structure in mediating perturbation cascades when interaction strength is incorporated. We combine empirical data on 18 mutualistic networks, two simulations scenarios, and network theory, to investigate how network structure affects perturbation spreading time, a proxy of network robustness to cascading effects. Simulations in which we included interaction strength presented higher mean spreading time, indicating that interaction strength increases network robustness. Richness, modularity, and nestedness had a strong, positive effect, on mean perturbation spreading time regardless of the interaction strengths. We found that network structure and the distribution of interaction strengths affected communities’ robustness to perturbation spreading. Our results contribute to the discussion on the danger that ecosystems face when species, and interactions alike, become extinct.
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Van Goor J, Piatscheck F, Houston DD, Nason JD. Figs, pollinators, and parasites: A longitudinal study of the effects of nematode infection on fig wasp fitness. ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY 2018. [DOI: 10.1016/j.actao.2018.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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15
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Pahua VJ, Stokes PJN, Hollowell AC, Regus JU, Gano‐Cohen KA, Wendlandt CE, Quides KW, Lyu JY, Sachs JL. Fitness variation among host species and the paradox of ineffective rhizobia. J Evol Biol 2018; 31:599-610. [DOI: 10.1111/jeb.13249] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 01/12/2018] [Accepted: 01/29/2018] [Indexed: 01/31/2023]
Affiliation(s)
- V. J. Pahua
- Department of Evolution Ecology and Organismal Biology University of California Riverside CA USA
| | - P. J. N. Stokes
- Department of Botany and Plant Sciences University of California Riverside CA USA
| | - A. C. Hollowell
- Department of Evolution Ecology and Organismal Biology University of California Riverside CA USA
| | - J. U. Regus
- Department of Evolution Ecology and Organismal Biology University of California Riverside CA USA
| | - K. A. Gano‐Cohen
- Department of Evolution Ecology and Organismal Biology University of California Riverside CA USA
| | - C. E. Wendlandt
- Department of Botany and Plant Sciences University of California Riverside CA USA
| | - K. W. Quides
- Department of Evolution Ecology and Organismal Biology University of California Riverside CA USA
| | - J. Y. Lyu
- Department of Evolution Ecology and Organismal Biology University of California Riverside CA USA
| | - J. L. Sachs
- Department of Evolution Ecology and Organismal Biology University of California Riverside CA USA
- Department of Botany and Plant Sciences University of California Riverside CA USA
- Institute for Integrative Genome Biology University of California Riverside CA USA
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16
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Friberg M, Waters MT, Thompson JN. Nutrient availability affects floral scent much less than other floral and vegetative traits in Lithophragma bolanderi. ANNALS OF BOTANY 2017; 120:471-478. [PMID: 28655187 PMCID: PMC5591434 DOI: 10.1093/aob/mcx069] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Revised: 01/09/2017] [Indexed: 05/29/2023]
Abstract
Background and Aims Many plant-pollinator interactions are mediated by floral scents that can vary among species, among populations within species and even among individuals within populations. This variation could be innate and unaffected by the environment, but, because many floral volatiles have amino-acid precursors, scent variation also could be affected by differences in nutrient availability among environments. In plants that have coevolved with specific pollinators, natural selection is likely to favour low phenotypic plasticity in floral scent even under different conditions of nutrient availability if particular scents or scent combinations are important for attracting local pollinators. Methods Clonal pairs of multiple seed-families of two Lithophragma bolanderi (Saxifragaceae) populations were subjected to a high and a low nutrient treatment. These plants are pollinated primarily by host-specific Greya moths. It was evaluated how nutrient treatment affected variation in floral scent relative to other vegetative and reproductive traits. Key Results Floral scent strength (the per-flower emission rate) and composition were unaffected by nutrient treatment, but low-nutrient plants produced fewer and lighter leaves, fewer scapes and fewer flowers than high-nutrient plants. The results held in both populations, which differed greatly in the number and composition of floral scents produced. Conclusions The results reveal a strong genetic component both to scent composition and emission level, and partly contrasts with the only previous study that has assessed the susceptibility of floral volatile signals to variation in the abundance of nutrients. These results, and the tight coevolutionary relationship between Lithophragma plants and their specialized Greya moth pollinators, indicate that reproductive traits important to coevolving interactions, such as the floral scent of L. bolanderi, may be locally specialized and more canalized than other traits important for plant fitness.
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Affiliation(s)
- Magne Friberg
- Uppsala University, Department of Plant Ecology and Evolution, Evolutionary Biology Centre, EBC, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Mia T Waters
- University of California, Santa Cruz, Department of Ecology and Evolutionary Biology, Santa Cruz, CA, USA
| | - John N Thompson
- University of California, Santa Cruz, Department of Ecology and Evolutionary Biology, Santa Cruz, CA, USA
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Thompson JN, Schwind C, Friberg M. Diversification of Trait Combinations in Coevolving Plant and Insect Lineages. Am Nat 2017; 190:171-184. [PMID: 28731801 DOI: 10.1086/692164] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Closely related species often have similar traits and sometimes interact with the same species. A crucial problem in evolutionary ecology is therefore to understand how coevolving species diverge when they interact with a set of closely related species from another lineage rather than with a single species. We evaluated geographic differences in the floral morphology of all woodland star plant species (Lithophragma, Saxifragaceae) that are pollinated by Greya (Prodoxidae) moths. Flowers of each woodland star species differed depending on whether plants interact locally with one, two, or no pollinating moth species. Plants of one species grown in six different environments showed few differences in floral traits, suggesting that the geographic differences are not due significantly to trait plasticity. Greya moth populations also showed significant geographic divergence in morphology, depending on the local host and on whether the moth species co-occurred locally. Divergence in the plants and the moths involved shifts in combinations of partially correlated traits, rather than any one trait. The results indicate that the geographic mosaic of coevolution can be amplified as coevolving lineages diversify into separate species and come together in different combinations in different ecosystems.
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18
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Rodríguez-Rodríguez MC, Jordano P, Valido A. Functional consequences of plant-animal interactions along the mutualism-antagonism gradient. Ecology 2017; 98:1266-1276. [PMID: 28135774 DOI: 10.1002/ecy.1756] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 01/17/2017] [Accepted: 01/24/2017] [Indexed: 11/10/2022]
Abstract
Plant-animal interactions are pivotal for ecosystem functioning, and usually form complex networks involving multiple species of mutualists as well as antagonists. The costs and benefits of these interactions show a strong context-dependency directly related to individual variation in partner identity and differential strength. Yet understanding the context-dependency and functional consequences of mutualistic and antagonistic interactions on individuals remains a lasting challenge. We use a network approach to characterize the individual, plant-based pollination interaction networks of the Canarian Isoplexis canariensis (Plantaginaceae) with a mixed assemblage of vertebrate mutualists (birds and lizards) and invertebrate antagonists (florivores, nectar larcenists, and predispersal seed predators). We identify and quantify interaction typologies based on the sign (mutualistic vs. antagonistic) and strength (weak vs. strong) of animal-mediated pollination and test the relationship with individual female reproductive success (FRS). In addition, we document pollinator movement patterns among individual plants to infer events of pollen transfer/receipt that define the plant mating networks and test the relationship with FRS. We identify six interaction typologies along a mutualism-antagonism gradient, with two typologies being over-represented involving both mutualists and antagonists and influencing FRS. Plants showing strong mutualistic interactions, but also (weak or strong) interactions with antagonists are relatively better connected in the mating network (i.e., with higher potential to transfer or receive pollen). Thus, mixed flower visitor assemblages with mutualists and antagonists give plants increased their importance in the mating networks, promote outcrossing and increasing both female and male fitness. Our approach helps characterize plant-animal interaction typologies, the context-specificity of diversified mutualisms, and a better forecasting of their functional consequences.
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Affiliation(s)
- María C Rodríguez-Rodríguez
- Department of Integrative Ecology, Estación Biológica de Doñana (EBD-CSIC), C/Americo Vespucio 26, Isla de la Cartuja, 41092, Sevilla, Spain
| | - Pedro Jordano
- Department of Integrative Ecology, Estación Biológica de Doñana (EBD-CSIC), C/Americo Vespucio 26, Isla de la Cartuja, 41092, Sevilla, Spain
| | - Alfredo Valido
- Department of Integrative Ecology, Estación Biológica de Doñana (EBD-CSIC), C/Americo Vespucio 26, Isla de la Cartuja, 41092, Sevilla, Spain
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19
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Cheptou PO, Hargreaves AL, Bonte D, Jacquemyn H. Correction to 'Adaptation to fragmentation: evolutionary dynamics driven by human influences'. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2016.0541. [PMID: 28193825 DOI: 10.1098/rstb.2016.0541] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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20
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Armbruster WS. The specialization continuum in pollination systems: diversity of concepts and implications for ecology, evolution and conservation. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12783] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- William Scott Armbruster
- School of Biological Sciences University of Portsmouth PortsmouthPO1 2DY UK
- Institute of Arctic Biology University of Alaska Fairbanks Fairbanks AK99775‐7000 USA
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21
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Yoder JB. Understanding the coevolutionary dynamics of mutualism with population genomics. AMERICAN JOURNAL OF BOTANY 2016; 103:1742-1752. [PMID: 27756732 DOI: 10.3732/ajb.1600154] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 09/06/2016] [Indexed: 06/06/2023]
Abstract
Decades of research on the evolution of mutualism has generated a wealth of possible ways whereby mutually beneficial interactions between species persist in spite of the apparent advantages to individuals that accept the benefits of mutualism without reciprocating - but identifying how any particular empirical system is stabilized against cheating remains challenging. Different hypothesized models of mutualism stability predict different forms of coevolutionary selection, and emerging high-throughput sequencing methods allow examination of the selective histories of mutualism genes and, thereby, the form of selection acting on those genes. Here, I review the evolutionary theory of mutualism stability and identify how differing models make contrasting predictions for the population genomic diversity and geographic differentiation of mutualism-related genes. As an example of the possibilities offered by genomic data, I analyze genes with roles in the symbiosis of Medicago truncatula and nitrogen-fixing rhizobial bacteria, the first classic mutualism in which extensive genomic resources have been developed for both partners. Medicago truncatula symbiosis genes, as a group, differ from the rest of the genome, but they vary in the form of selection indicated by their diversity and differentiation - some show signs of selection expected from roles in sanctioning noncooperative symbionts, while others show evidence of balancing selection expected from coevolution with symbiont signaling factors. I then assess the current state of development for similar resources in other mutualistic interactions and look ahead to identify ways in which modern sequencing technology can best inform our understanding of mutualists and mutualism.
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Affiliation(s)
- Jeremy B Yoder
- Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4 Canada
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22
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Nunes CEP, Peñaflor MFGV, Bento JMS, Salvador MJ, Sazima M. The dilemma of being a fragrant flower: the major floral volatile attracts pollinators and florivores in the euglossine-pollinated orchid Dichaea pendula. Oecologia 2016; 182:933-946. [PMID: 27538674 DOI: 10.1007/s00442-016-3703-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 08/09/2016] [Indexed: 01/01/2023]
Abstract
Volatile organic compounds (VOCs) mediate both mutualistic and antagonistic plant-animal interactions; thus, the attraction of mutualists and antagonists by floral VOCs constitutes an important trade-off in the evolutionary ecology of angiosperms. Here, we evaluate the role of VOCs in mediating communication between the plant and its mutualist and antagonist floral visitors. To assess the evolutionary consequences of VOC-mediated signalling to distinct floral visitors, we studied the reproductive ecology of Dichaea pendula, assessing the effects of florivores on fruit set, the pollination efficiency of pollinators and florivores, the floral scent composition and the attractiveness of the major VOC to pollinators and florivores. The orchid depends entirely on orchid-bees for sexual reproduction, and the major florivores, the weevils, feed on corollas causing self-pollination, triggering abortion of 26.4 % of the flowers. Floral scent was composed of approximately 99 % 2-methoxy-4-vinylphenol, an unusual floral VOC attractive to pollinators and florivores. The low fruit set from natural pollination (5.6 %) compared to hand cross-pollination (45.5 %) and low level of pollinator visitation [0.02 visits (flower hour)-1] represent the limitations to pollination. Our research found that 2-methoxy-4-vinylphenol mediates both mutualistic and antagonistic interactions, which could result in contrary evolutionary pressures on novo-emission. The scarcity of pollinators, not florivory, was the major constraint to fruit set. Our results suggest that, rather than anti-florivory adaptations, adaptations to enhance pollinator attraction and cross-pollination might be the primary drivers of the evolution of VOC emission in euglossine-pollinated flowers.
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Affiliation(s)
- Carlos E P Nunes
- Graduate Program in Plant Biology, University of Campinas, Rua Monteiro Lobato 255, Cidade Universitária "Zeferino Vaz", Campinas, 13083-970, Brazil.
| | - Maria Fernanda G V Peñaflor
- Department of Entomology and Acarology, University of São Paulo, Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ), Piracicaba, Brazil
| | - José Maurício S Bento
- Department of Entomology and Acarology, University of São Paulo, Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ), Piracicaba, Brazil
| | - Marcos José Salvador
- Department of Plant Biology, Institute of Biology, University of Campinas, Campinas, Brazil
| | - Marlies Sazima
- Department of Plant Biology, Institute of Biology, University of Campinas, Campinas, Brazil
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23
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Ho WW, Riffell JA. The Olfactory Neuroecology of Herbivory, Hostplant Selection and Plant-Pollinator Interactions. Integr Comp Biol 2016; 56:856-864. [PMID: 27471226 DOI: 10.1093/icb/icw096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Plants experience often opposing energetic demands and selective pressures-for instance, where plants need to attract an insect that is both the pollinator and herbivore, or alternately, where plants attract prey (due to limited resources) and pollinators. Together, these selective pressures can modify the volatile signals available to the plant's mutualistic and antagonistic partners. Nevertheless, it remains an open question how changes in the information content of volatile signals modify behavioral responses in mutualists and antagonists, and what the underlying neural bases of these behaviors are. This review focuses on two systems to explore the impact of herbivory and resource availability on plant-pollinator interactions: hawkmoth-pollinated hostplants (where herbivory is common), and carnivorous bee-pollinated pitcher plants (where the plants differentially attract bee pollinators and other insect prey). We focus on (1) the volatile signals emitted from these plants because these volatiles operate as long-distance signals to attract, or deter, insect partners, (2) how this information is processed in the hawkmoth olfactory system, and (3) how volatile information changes spatiotemporally. In both the plants and their respective insect partner(s), volatile signaling, reception and behavior are dynamic and plastic, providing flexibility an ever-changing environment.
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Affiliation(s)
- Winnie W Ho
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - Jeffrey A Riffell
- Department of Biology, University of Washington, Seattle, WA 98195, USA
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24
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Friberg M, Schwind C, Thompson JN. Divergence in selection of host species and plant parts among populations of a phytophagous insect. Evol Ecol 2016. [DOI: 10.1007/s10682-016-9835-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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25
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Why Do Floral Perfumes Become Different? Region-Specific Selection on Floral Scent in a Terrestrial Orchid. PLoS One 2016; 11:e0147975. [PMID: 26886766 PMCID: PMC4757410 DOI: 10.1371/journal.pone.0147975] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 01/11/2016] [Indexed: 12/01/2022] Open
Abstract
Geographically structured phenotypic selection can lead to adaptive divergence. However, in flowering plants, such divergent selection has rarely been shown, and selection on floral signals is generally little understood. In this study, we measured phenotypic selection on display size, floral color, and floral scent in four lowland and four mountain populations of the nectar-rewarding terrestrial orchid Gymnadenia odoratissima in two years. We also quantified population differences in these traits and pollinator community composition. Our results show positive selection on display size and positive, negative, or absence of selection on different scent compounds and floral color. Selection on the main scent compounds was consistently stronger in the lowlands than in the mountains, and lowland plants emitted higher amounts of most of these compounds. Pollinator community composition also differed between regions, suggesting different pollinators select for differences in floral volatiles. Overall, our study is the first to document consistent regional differences in selection on floral scent, suggesting this pattern of selection is one of the evolutionary forces contributing to regional divergence in floral chemical signaling.
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26
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Suchan T, Beauverd M, Trim N, Alvarez N. Asymmetrical nature of the Trollius-Chiastocheta interaction: insights into the evolution of nursery pollination systems. Ecol Evol 2015; 5:4766-77. [PMID: 26640658 PMCID: PMC4662325 DOI: 10.1002/ece3.1544] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 04/25/2015] [Accepted: 05/04/2015] [Indexed: 11/28/2022] Open
Abstract
The mutualistic versus antagonistic nature of an interaction is defined by costs and benefits of each partner, which may vary depending on the environment. Contrasting with this dynamic view, several pollination interactions are considered as strictly obligate and mutualistic. Here, we focus on the interaction between Trollius europaeus and Chiastocheta flies, considered as a specialized and obligate nursery pollination system – the flies are thought to be exclusive pollinators of the plant and their larvae develop only in T. europaeus fruits. In this system, features such as the globelike flower shape are claimed to have evolved in a coevolutionary context. We examine the specificity of this pollination system and measure traits related to offspring fitness in isolated T. europaeus populations, in some of which Chiastocheta flies have gone extinct. We hypothesize that if this interaction is specific and obligate, the plant should experience dramatic drop in its relative fitness in the absence of Chiastocheta. Contrasting with this hypothesis, T. europaeus populations without flies demonstrate a similar relative fitness to those with the flies present, contradicting the putative obligatory nature of this pollination system. It also agrees with our observation that many other insects also visit and carry pollen among T. europaeus flowers. We propose that the interaction could have evolved through maximization of by‐product benefits of the Chiastocheta visits, through the male flower function, and selection on floral traits by the most effective pollinator. We argue this mechanism is also central in the evolution of other nursery pollination systems.
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Affiliation(s)
- Tomasz Suchan
- Department of Ecology and Evolution University of Lausanne Biophore Building 1015 Lausanne Switzerland ; Institute of Environmental Biology University of Wrocław ul. Kanonia 6/8 50-328 Wrocław Poland
| | - Mélanie Beauverd
- Department of Ecology and Evolution University of Lausanne Biophore Building 1015 Lausanne Switzerland
| | - Naïké Trim
- Department of Ecology and Evolution University of Lausanne Biophore Building 1015 Lausanne Switzerland
| | - Nadir Alvarez
- Department of Ecology and Evolution University of Lausanne Biophore Building 1015 Lausanne Switzerland
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27
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Wang RW, Dunn DW, Luo J, He JZ, Shi L. The importance of spatial heterogeneity and self-restraint on mutualism stability - a quantitative review. Sci Rep 2015; 5:14826. [PMID: 26434680 PMCID: PMC4593180 DOI: 10.1038/srep14826] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 09/07/2015] [Indexed: 12/18/2022] Open
Abstract
Understanding the factors that enable mutualisms to evolve and to subsequently remain stable over time, is essential to fully understand patterns of global biodiversity and for evidence based conservation policy. Theoretically, spatial heterogeneity of mutualists, through increased likelihood of fidelity between cooperative partners in structured populations, and ‘self-restraint’ of symbionts, due to selection against high levels of virulence leading to short-term host overexploitation, will result in either a positive correlation between the reproductive success of both mutualists prior to the total exploitation of any host resource or no correlation after any host resource has been fully exploited. A quantitative review by meta-analysis on the results of 96 studies from 35 papers, showed no evidence of a significant fitness correlation between mutualists across a range of systems that captured much taxonomic diversity. However, when the data were split according to four categories of host: 1) cnidarian corals, 2) woody plants, 3) herbaceous plants, and 4) insects, a significantly positive effect in corals was revealed. The trends for the remaining three categories did not significantly differ to zero. Our results suggest that stability in mutualisms requires alternative processes, or mechanisms in addition to, spatial heterogeneity of hosts and/or ‘self-restraint’ of symbionts.
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Affiliation(s)
- Rui-Wu Wang
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an, 710072, China.,Kunming Institute of Zoology, Chinese Academy of Science, Kunming, Yunnan, 650223, China
| | - Derek W Dunn
- Kunming Institute of Zoology, Chinese Academy of Science, Kunming, Yunnan, 650223, China
| | - Jun Luo
- Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Jun-Zhou He
- Kunming Institute of Zoology, Chinese Academy of Science, Kunming, Yunnan, 650223, China.,Statistics and Mathematics College, Yunnan University of Finance and Economics, Kunming, Yunnan, 650221, China
| | - Lei Shi
- Statistics and Mathematics College, Yunnan University of Finance and Economics, Kunming, Yunnan, 650221, China
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28
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Poisot T, Bever JD, Thrall PH, Hochberg ME. Dispersal and spatial heterogeneity allow coexistence between enemies and protective mutualists. Ecol Evol 2014; 4:3841-50. [PMID: 25614798 PMCID: PMC4301050 DOI: 10.1002/ece3.1151] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Protective mutualisms, where a symbiont reduces the negative effects of another species on a shared host, represent a common type of species interaction in natural communities, yet it is still unclear what ecological conditions might favor their emergence. Studies suggest that the initial evolution of protective mutualists might involve closely related pathogenic variants with similar life histories, but different competitive abilities and impacts on host fitness. We derive a model to evaluate this hypothesis and show that, in general, a protective variant cannot spread from rarity or exclude a more pathogenic strain. While the conditions allowing mutualist invasion are more likely with increased environmental productivity, they still depend on initial densities in the invaded patch exceeding a threshold, highlighting the likely importance of spatial structure and demographic stochasticity. Using a numerical simulation approach, we show that regional coexistence is in fact possible in an explicitly spatial system and that, under some circumstances, the mutualist population can exclude the enemy. More broadly, the establishment of protective mutualists may be favored when there are other life-history differences from more pathogenic symbionts, such as vertical transmission or additional direct benefits to hosts.
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Affiliation(s)
- Timothée Poisot
- Université Montpellier II, Institut des Sciences de l'Evolution, UMR 5554Place Eugène Bataillon, 34095, Montpellier, CEDEX 05, France
- Département de Biologie, Université du Québec à Rimouski300 Allée des Ursulines, Rimouski, Quebec, G5L 3A1, Canada
- Québec Centre for Biodiversity SciencesMontréal (QC), Canada
- School of Biological Sciences, University of CanterburyPrivate Bag, 4800, Christchurch, 8140, New Zealand
| | - James D Bever
- Department of Biology, Indiana UniversityBloomington, Indiana, 47405
| | - Peter H Thrall
- CSIRO Plant IndustryGPO Box 1600, Canberra, Australian Capital Territory, 2601, Australia
| | - Michael E Hochberg
- Université Montpellier II, Institut des Sciences de l'Evolution, UMR 5554Place Eugène Bataillon, 34095, Montpellier, CEDEX 05, France
- Santa Fe InstituteSanta Fe, New Mexico, 87501
- Wissenschaftskolleg zu BerlinBerlin, 14193, Germany
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29
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Friberg M, Schwind C, Roark LC, Raguso RA, Thompson JN. Floral scent contributes to interaction specificity in coevolving plants and their insect pollinators. J Chem Ecol 2014; 40:955-65. [PMID: 25236381 DOI: 10.1007/s10886-014-0497-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 07/19/2014] [Accepted: 07/21/2014] [Indexed: 10/24/2022]
Abstract
Chemical defenses, repellents, and attractants are important shapers of species interactions. Chemical attractants could contribute to the divergence of coevolving plant-insect interactions, if pollinators are especially responsive to signals from the local plant species. We experimentally investigated patterns of daily floral scent production in three Lithophragma species (Saxifragaceae) that are geographically isolated and tested how scent divergence affects attraction of their major pollinator-the floral parasitic moth Greya politella (Prodoxidae). These moths oviposit through the corolla while simultaneously pollinating the flower with pollen adhering to the abdomen. The complex and species-specific floral scent profiles were emitted in higher amounts during the day, when these day-flying moths are active. There was minimal divergence found in petal color, which is another potential floral attractant. Female moths responded most strongly to scent from their local host species in olfactometer bioassays, and were more likely to oviposit in, and thereby pollinate, their local host species in no-choice trials. The results suggest that floral scent is an important attractant in this interaction. Local specialization in the pollinator response to a highly specific plant chemistry, thus, has the potential to contribute importantly to patterns of interaction specificity among coevolving plants and highly specialized pollinators.
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Affiliation(s)
- Magne Friberg
- Department of Ecology and Evolutionary Biology, University of California, 1156 High Street, Santa Cruz, CA, 95064, USA,
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Abstract
Coevolution, reciprocal adaptation between two or more taxa, is commonly invoked as a primary mechanism responsible for generating much of Earth's biodiversity. This conceptually appealing hypothesis is incredibly broad in evolutionary scope, encompassing diverse patterns and processes operating over timescales ranging from microbial generations to geological eras. However, we have surprisingly little evidence that large-scale associations between coevolution and diversity reflect a causal relationship at smaller timescales, in which coevolutionary selection is directly responsible for the formation of new species. In this synthesis, we critically evaluate evidence for the often-invoked hypothesis that coevolution is an important process promoting biological diversification. We conclude that the lack of widespread evidence for coevolutionary diversification may be best explained by the fact that coevolution's importance in diversification varies depending on the type of interaction and the scale of the diversification under consideration.
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Affiliation(s)
- David H Hembry
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California 94720
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Kula AAR, Castillo DM, Dudash MR, Fenster CB. Interactions between a pollinating seed predator and its host plant: the role of environmental context within a population. Ecol Evol 2014; 4:2901-12. [PMID: 25165527 PMCID: PMC4130447 DOI: 10.1002/ece3.1134] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 04/30/2014] [Indexed: 11/09/2022] Open
Abstract
Plant-insect interactions often are important for plant reproduction, but the outcome of these interactions may vary with environmental context. Pollinating seed predators have positive and negative effects on host plant reproduction, and the interaction outcome is predicted to vary with density or abundance of the partners. We studied the interaction between Silene stellata, an herbaceous perennial, and Hadena ectypa, its specialized pollinating seed predator. Silene stellata is only facultatively dependent upon H. ectypa for pollination because other nocturnal moth co-pollinators are equally effective at pollen transfer. We hypothesized that for plants without conspecific neighbors, H. ectypa would have higher visitation rates compared to co-pollinators, and the plants would experience lower levels of H. ectypa pollen deposition. We predicted similar oviposition throughout the study site but greater H. ectypa predation in the area without conspecific neighbors compared to plants embedded in a naturally high density area. We found that H. ectypa had consistently higher visitation than moth co-pollinators in all host plant contexts. However, H. ectypa pollinator importance declined in areas with low conspecific density because of reduced pollen deposition, resulting in lower seed set. Conversely, oviposition was similar across the study site independent of host plant density. Greater likelihood of very high fruit predation combined with lower pollination by H. ectypa resulted in reduced S. stellata female reproductive success in areas with low conspecific density. Our results demonstrate local context dependency of the outcomes of pollinating seed predator interactions with conspecific host plant density within a population.
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Affiliation(s)
- Abigail A R Kula
- Department of Biology, University of Maryland College Park, Maryland, 20742 ; Mountain Lake Biological Station Pembroke, Virginia, 24136
| | - Dean M Castillo
- Mountain Lake Biological Station Pembroke, Virginia, 24136 ; Department of Biology, Indiana University Bloomington, Indiana, 47405
| | - Michele R Dudash
- Department of Biology, University of Maryland College Park, Maryland, 20742 ; Mountain Lake Biological Station Pembroke, Virginia, 24136
| | - Charles B Fenster
- Department of Biology, University of Maryland College Park, Maryland, 20742 ; Mountain Lake Biological Station Pembroke, Virginia, 24136
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32
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Wang R, Yang Y, Wiggins NL. Asymmetric or diffusive co-evolution generates meta-populations in fig-fig wasp mutualisms. SCIENCE CHINA-LIFE SCIENCES 2014; 57:596-602. [PMID: 24829105 DOI: 10.1007/s11427-014-4653-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 11/25/2013] [Indexed: 11/26/2022]
Abstract
Co-evolutionary theory assumes co-adapted characteristics are a positive response to counter those of another species, whereby co-evolved species reach an evolutionarily stable interaction through bilateral adaptation. However, evidence from the fig-fig wasp mutualistic system implies very different co-evolutionary selection mechanisms, due to the inherent conflict among interacted partners. Fig plants appear to have discriminatively enforced fig wasps to evolve "adaptation characteristics" that provide greater benefit to the fig, and fig wasps appear to have diversified their evolutionary strategies in response to discriminative enforcement by figs and competition among different fig wasp species. In what appears to be an asymmetric interaction, the prosperity of cooperative pollinating wasps should inevitably lead to population increases of parasitic individuals, thus resulting in localized extinctions of pollinating wasps. In response, the sanctioning of parasitic wasps by the fig should lead to a reduction in the parasitic wasp population. The meta-populations created by such asymmetric interactions may result in each population of coevolved species chaotically oscillated, temporally or evolutionarily.
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Affiliation(s)
- RuiWu Wang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, China,
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33
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Larimer AL, Clay K, Bever JD. Synergism and context dependency of interactions between arbuscular mycorrhizal fungi and rhizobia with a prairie legume. Ecology 2014; 95:1045-54. [DOI: 10.1890/13-0025.1] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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35
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Heath KD, Stinchcombe JR. EXPLAINING MUTUALISM VARIATION: A NEW EVOLUTIONARY PARADOX? Evolution 2013; 68:309-17. [DOI: 10.1111/evo.12292] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 10/06/2013] [Indexed: 12/12/2022]
Affiliation(s)
- Katy D. Heath
- Department of Plant Biology; University of Illinois Urbana-Champaign; 265 Morrill Hall, 505 S. Goodwin Avenue Urbana Illinois 61801
| | - John R. Stinchcombe
- Department of Ecology and Evolutionary Biology; University of Toronto; 25 Willcocks Street Toronto Ontario M5S 3B2 Canada
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36
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Diversification through multitrait evolution in a coevolving interaction. Proc Natl Acad Sci U S A 2013; 110:11487-92. [PMID: 23801764 DOI: 10.1073/pnas.1307451110] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mutualisms between species are interactions in which reciprocal exploitation results in outcomes that are mutually beneficial. This reciprocal exploitation is evident in the more than a thousand plant species that are pollinated exclusively by insects specialized to lay their eggs in the flowers they pollinate. By pollinating each flower in which she lays eggs, an insect guarantees that her larval offspring have developing seeds on which to feed, whereas the plant gains a specialized pollinator at the cost of some seeds. These mutualisms are often reciprocally obligate, potentially driving not only ongoing coadaptation but also diversification. The lack of known intermediate stages in most of these mutualisms, however, makes it difficult to understand whether these interactions could have begun to diversify even before they became reciprocally obligate. Experimental studies of the incompletely obligate interactions between woodland star (Lithophragma; Saxifragaceae) plants and their pollinating floral parasites in the moth genus Greya (Prodoxidae) show that, as these lineages have diversified, the moths and plants have evolved in ways that maintain effective oviposition and pollination. Experimental assessment of pollination in divergent species and quantitative evaluation of time-lapse photographic sequences of pollination viewed on surgically manipulated flowers show that various combinations of traits are possible for maintaining the mutualism. The results suggest that at least some forms of mutualism can persist and even diversify when the interaction is not reciprocally obligate.
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Harrison E, Laine AL, Hietala M, Brockhurst MA. Rapidly fluctuating environments constrain coevolutionary arms races by impeding selective sweeps. Proc Biol Sci 2013; 280:20130937. [PMID: 23760864 PMCID: PMC3712419 DOI: 10.1098/rspb.2013.0937] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Although pervasive, the impact of temporal environmental heterogeneity on coevolutionary processes is poorly understood. Productivity is a key temporally heterogeneous variable, and increasing productivity has been shown to increase rates of antagonistic arms race coevolution, and lead to the evolution of more broadly resistant hosts and more broadly infectious parasites. We investigated the effects of the grain of environmental heterogeneity, in terms of fluctuations in productivity, on bacteria–phage coevolution. Our findings demonstrate that environmental heterogeneity could constrain antagonistic coevolution, but that its effect was dependent upon the grain of heterogeneity, such that both the rate and extent of coevolution were most strongly limited in fine-grained, rapidly fluctuating heterogeneous environments. We further demonstrate that rapid environmental fluctuations were likely to have impeded selective sweeps of resistance alleles, which occurred over longer durations than the fastest, but not the slowest, frequency of fluctuations used. Taken together our results suggest that fine-grained environmental heterogeneity constrained the coevolutionary arms race by impeding selective sweeps.
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Affiliation(s)
- Ellie Harrison
- Department of Biology, University of York, York YO10 5DD, UK
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Castillo G, Cruz LL, Hernández-Cumplido J, Oyama K, Flores-Ortiz CM, Fornoni J, Valverde PL, Núñez-Farfán J. Geographic association and temporal variation of chemical and physical defense and leaf damage in Datura stramonium. Ecol Res 2013. [DOI: 10.1007/s11284-013-1059-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Friberg M, Schwind C, Raguso RA, Thompson JN. Extreme divergence in floral scent among woodland star species (Lithophragma spp.) pollinated by floral parasites. ANNALS OF BOTANY 2013; 111:539-550. [PMID: 23365407 PMCID: PMC3605946 DOI: 10.1093/aob/mct007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 12/11/2012] [Indexed: 05/31/2023]
Abstract
BACKGROUNDS AND AIMS A current challenge in coevolutionary biology is to understand how suites of traits vary as coevolving lineages diverge. Floral scent is often a complex, variable trait that attracts a suite of generalized pollinators, but may be highly specific in plants specialized on attracting coevolved pollinating floral parasites. In this study, floral scent variation was investigated in four species of woodland stars (Lithophragma spp.) that share the same major pollinator (the moth Greya politella, a floral parasite). Three specific hypotheses were tested: (1) sharing the same specific major pollinator favours conservation of floral scent among close relatives; (2) selection favours 'private channels' of rare compounds particularly aimed at the specialist pollinator; or (3) selection from rare, less-specialized co-pollinators mitigates the conservation of floral scent and occurrence of private channels. METHODS Dynamic headspace sampling and solid-phase microextraction were applied to greenhouse-grown plants from a common garden as well as to field samples from natural populations in a series of experiments aiming to disentangle the genetic and environmental basis of floral scent variation. KEY RESULTS Striking floral scent divergence was discovered among species. Only one of 69 compounds was shared among all four species. Scent variation was largely genetically based, because it was consistent across field and greenhouse treatments, and was not affected by visits from the pollinating floral parasite. CONCLUSIONS The strong divergence in floral scents among Lithophragma species contrasts with the pattern of conserved floral scent composition found in other plant genera involved in mutualisms with pollinating floral parasites. Unlike some of these other obligate pollination mutualisms, Lithophragma plants in some populations are occasionally visited by generalist pollinators from other insect taxa. This additional complexity may contribute to the diversification in floral scent found among the Lithophragma species pollinated by Greya moths.
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Affiliation(s)
- Magne Friberg
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95064, USA.
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Singer MC, McBride CS. Geographic mosaics of species' association: a definition and an example driven by plant–insect phenological synchrony. Ecology 2012; 93:2658-73. [DOI: 10.1890/11-2078.1] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Ivens ABF, Kronauer DJC, Pen I, Weissing FJ, Boomsma JJ. Ants farm subterranean aphids mostly in single clone groups--an example of prudent husbandry for carbohydrates and proteins? BMC Evol Biol 2012; 12:106. [PMID: 22747564 PMCID: PMC3499235 DOI: 10.1186/1471-2148-12-106] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 05/16/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mutualistic interactions are wide-spread but the mechanisms underlying their evolutionary stability and ecological dynamics remain poorly understood. Cultivation mutualisms in which hosts consume symbionts occur in phylogenetically diverse groups, but often have symbiont monocultures for each host. This is consistent with the prediction that symbionts should avoid coexistence with other strains so that host services continue to benefit relatives, but it is less clear whether hosts should always favor monocultures and what mechanisms they might have to manipulate symbiont diversity. Few mutualisms have been studied in sufficient genetic detail to address these issues, so we decided to characterize symbiont diversity in the complex mutualism between multiple root aphid species and Lasius flavus ants. After showing elsewhere that three of these aphid species have low dispersal and mostly if not exclusively asexual reproduction, we here investigate aphid diversity within and between ant nest mounds. RESULTS The three focal species (Geoica utricularia, Forda marginata and Tetraneura ulmi) had considerable clonal diversity at the population level. Yet more than half of the ant mounds contained just a single aphid species, a significantly higher percentage than expected from a random distribution. Over 60% of these single-species mounds had a single aphid clone, and clones tended to persist across subsequent years. Whenever multiple species/clones co-occurred in the same mound, they were spatially separated with more than 95% of the aphid chambers containing individuals of a single clone. CONCLUSIONS L. flavus "husbandry" is characterized by low aphid "livestock" diversity per colony, especially at the nest-chamber level, but it lacks the exclusive monocultures known from other cultivation mutualisms. The ants appear to eat most of the early instar aphids, so that adult aphids are unlikely to face limited phloem resources and scramble competition with other aphids. We suggest that such culling of carbohydrate-providing symbionts for protein ingestion may maintain maximal host yield per aphid while also benefitting the domesticated aphids as long as their clone-mates reproduce successfully. The cost-benefit logic of this type of polyculture husbandry has striking analogies with human farming practices based on slaughtering young animals for meat to maximize milk-production by a carefully regulated adult livestock population.
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Affiliation(s)
- Aniek B F Ivens
- Theoretical Biology, Centre for Ecological and Evolutionary Studies, University of Groningen, Groningen, The Netherlands.
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Janz N. Ehrlich and Raven Revisited: Mechanisms Underlying Codiversification of Plants and Enemies. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2011. [DOI: 10.1146/annurev-ecolsys-102710-145024] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Niklas Janz
- Department of Zoology, Stockholm University, 106 91 Stockholm, Sweden;
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Chen F, Chen J. Dispersal syndrome differentiation of Pinus armandii in Southwest China: Key elements of a potential selection mosaic. ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY 2011. [DOI: 10.1016/j.actao.2011.05.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Genini J, Côrtes MC, Guimarães Jr PR, Galetti M. Mistletoes Play Different Roles in a Modular Host-Parasite Network. Biotropica 2011. [DOI: 10.1111/j.1744-7429.2011.00794.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Rodríguez-Rodríguez MC, Valido A. Consequences of plant-pollinator and floral-herbivore interactions on the reproductive success of the Canary Islands endemic Canarina canariensis (Campanulaceae). AMERICAN JOURNAL OF BOTANY 2011; 98:1465-1474. [PMID: 21900611 DOI: 10.3732/ajb.1100146] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
PREMISE OF THE STUDY Pollination is a critical phase for plant reproduction, but ecological and evolutionary outcomes by pollinators may be counteracted by floral herbivores. These interacting assemblages may also be altered (directly or indirectly) by introduced species, especially on oceanic islands. In this study, we analyzed the effects of opportunistic nectar-feeding passerine birds and native (semi-slugs) and introduced (rats) floral herbivores on the reproductive success of Canarina canariensis. • METHODS Manual pollination experiments were conducted to determine plant breeding system and pollen limitation. We also identified floral visitors and their visitation frequencies by censuses. Bird pollination effectiveness was evaluated by selective exclosures. The intensity of floral herbivory by native vs. introduced herbivores and its effect on plant fitness was estimated in different areas within the Canary island of Tenerife. • KEY RESULTS Canarina canariensis had a very low spontaneous selfing ability and high pollen limitation, despite being self-compatible. Birds increased fruit set and the percentage of viable seeds per fruit, while florivores, the principal floral visitors, reduced them. Semi-slugs mainly consumed male reproductive organs, while rats preferred female. There was a strong within-island spatial variation in the herbivory intensity. • CONCLUSIONS Opportunistic nectar-feeding birds increase the production of viable seeds in C. canariensis, but their beneficial effects are counteracted by the high incidence of floral herbivory. Because native semi-slugs damaged anthers more frequently than did introduced rats, these florivores may differ in their effects on male and female plant reproductive success.
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Affiliation(s)
- María C Rodríguez-Rodríguez
- Integrative Ecology Group, Estación Biológica de Doñana (EBD-CSIC), C/ Américo Vespucio s/n, La Cartuja 41092 Sevilla, Spain.
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Variable nursery pollinator importance and its effect on plant reproductive success. Oecologia 2011; 168:439-48. [DOI: 10.1007/s00442-011-2095-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 07/21/2011] [Indexed: 10/17/2022]
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Shi L, Wang R, Zhu L, Zen W, Xu W, Zheng Q. Varying coefficient analysis for indeterminate species interactions with non-parametric estimation, exemplifying with a fig-fig wasp system. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/s11434-011-4564-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Lorenzi MC, Thompson JN. The geographic structure of selection on a coevolving interaction between social parasitic wasps and their hosts hampers social evolution. Evolution 2011; 65:3527-42. [PMID: 22133223 DOI: 10.1111/j.1558-5646.2011.01403.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Social parasites exploit societies, rather than organisms, and rear their brood in social insect colonies at the expense of their hosts, triggering a coevolutionary process that may affect host social structure. The resulting coevolutionary trajectories may be further altered by selection imposed by predators, which exploit the abundant resources concentrated in these nests. Here, we show that geographic differences in selection imposed by predators affects the structure of selection on coevolving hosts and their social parasites. In a multiyear study, we monitored the fate of the annual breeding attempts of the solitary nesting foundresses of Polistes biglumis wasps in four geographically distinct populations that varied in levels of attack by the congeneric social parasite, P. atrimandibularis. Foundress fitness depended mostly on whether, during the long founding phase, a colony was invaded by social parasites or attacked by predators. Foundresses from each population differed in morphological traits and reproductive tactics that were consistent with selection imposed by their natural enemies and in ways that may affect host sociality. In turn, parasite traits were consistent with selection imposed locally by hosts, implying a geographic mosaic of coevolution in this brood parasitic interaction.
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Affiliation(s)
- M Cristina Lorenzi
- Department of Animal and Human Biology, University of Turin, Via Accademia Albertina 13, 10123 Turin, Italy.
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Toju H, Abe H, Ueno S, Miyazawa Y, Taniguchi F, Sota T, Yahara T. Climatic gradients of arms race coevolution. Am Nat 2011; 177:562-73. [PMID: 21508604 DOI: 10.1086/659624] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
In nature, spatiotemporally dynamic coevolutionary processes play major roles in the foundation and maintenance of biodiversity. Here, we examined the arms race coevolution involving a seed-eating weevil with a long snout and its camellia plant host with a thick fruit coat (pericarp) throughout the marked climatic gradient observed across the Japanese islands. Results demonstrated that female weevils, which bored holes through camellia pericarps to lay eggs into seeds, had evolved much longer snouts than males, especially in areas in which Japanese camellia pericarps were very thick. The thickness of the plant pericarp was heritable, and the camellia plant evolved a significantly thicker pericarp on islands with the weevil than on islands without it. Across populations with weevils, resource allocation to plant defense increased with increasing annual mean temperature or annual precipitation, thereby geographically differentiating the evolutionary and ecological interactions between the two species. Given that the coevolutionary relationship exhibited appreciable variation across a relatively small range of annual mean temperatures, ongoing global climatic change can dramatically alter the coevolutionary process, thereby changing the ecological interaction between these species.
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Affiliation(s)
- Hirokazu Toju
- Graduate School of Science, Kyoto University, Sakyo, Japan.
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Vale PF, Wilson AJ, Best A, Boots M, Little TJ. Epidemiological, evolutionary, and coevolutionary implications of context-dependent parasitism. Am Nat 2011; 177:510-21. [PMID: 21460572 DOI: 10.1086/659002] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Abstract Victims of infection are expected to suffer increasingly as parasite population growth increases. Yet, under some conditions, faster-growing parasites do not appear to cause more damage, and infections can be quite tolerable. We studied these conditions by assessing how the relationship between parasite population growth and host health is sensitive to environmental variation. In experimental infections of the crustacean Daphnia magna and its bacterial parasite Pasteuria ramosa, we show how easily an interaction can shift from a severe interaction, that is, when host fitness declines substantially with each unit of parasite growth, to a tolerable relationship by changing only simple environmental variables: temperature and food availability. We explored the evolutionary and epidemiological implications of such a shift by modeling pathogen evolution and disease spread under different levels of infection severity and found that environmental shifts that promote tolerance ultimately result in populations harboring more parasitized individuals. We also find that the opportunity for selection, as indicated by the variance around traits, varied considerably with the environmental treatment. Thus, our results suggest two mechanisms that could underlie coevolutionary hotspots and coldspots: spatial variation in tolerance and spatial variation in the opportunity for selection.
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Affiliation(s)
- Pedro F Vale
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Ashworth Labs, West Mains Road, Edinburgh, Scotland, United Kingdom.
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