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Malé PJG, Turner KM, Doha M, Anreiter I, Allen AM, Sokolowski MB, Frederickson ME. An ant-plant mutualism through the lens of cGMP-dependent kinase genes. Proc Biol Sci 2018; 284:rspb.2017.0896. [PMID: 28904134 DOI: 10.1098/rspb.2017.0896] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 08/04/2017] [Indexed: 12/19/2022] Open
Abstract
In plant-animal mutualisms, how an animal forages often determines how much benefit its plant partner receives. In many animals, foraging behaviour changes in response to foraging gene expression or activation of the cGMP-dependent protein kinase (PKG) that foraging encodes. Here, we show that this highly conserved molecular mechanism affects the outcome of a plant-animal mutualism. We studied the two PKG genes of Allomerus octoarticulatus, an Amazonian ant that defends the ant-plant Cordia nodosa against herbivores. Some ant colonies are better 'bodyguards' than others. Working in the field in Peru, we found that colonies fed with a PKG activator recruited more workers to attack herbivores than control colonies. This resulted in less herbivore damage. PKG gene expression in ant workers correlated with whether an ant colony discovered an herbivore and how much damage herbivores inflicted on leaves in a complex way; natural variation in expression levels of the two genes had significant interaction effects on ant behaviour and herbivory. Our results suggest a molecular basis for ant protection of plants in this mutualism.
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Affiliation(s)
- Pierre-Jean G Malé
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
| | - Kyle M Turner
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
| | - Manjima Doha
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
| | - Ina Anreiter
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2.,Child and Brain Development Program, Canadian Institute for Advanced Research (CIFAR), MaRS Centre, West Tower, 661 University Avenue, Suite 505, Toronto, Ontario, Canada M5G 1M1
| | - Aaron M Allen
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, Ontario, Canada M5S 3G5
| | - Marla B Sokolowski
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2.,Child and Brain Development Program, Canadian Institute for Advanced Research (CIFAR), MaRS Centre, West Tower, 661 University Avenue, Suite 505, Toronto, Ontario, Canada M5G 1M1
| | - Megan E Frederickson
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
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Yoder JB, Tiffin P. Sanctions, Partner Recognition, and Variation in Mutualism. Am Nat 2017; 190:491-505. [DOI: 10.1086/693472] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Torres MF, Sanchez A. Neotropical ant-plant Triplaris americana attracts Pseudomyrmex mordax ant queens during seedling stages. INSECTES SOCIAUX 2017; 64:255-261. [PMID: 28479608 PMCID: PMC5397449 DOI: 10.1007/s00040-017-0542-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 12/19/2016] [Accepted: 01/07/2017] [Indexed: 06/07/2023]
Abstract
The association between the myrmecophyte Triplaris and ants of the genus Pseudomyrmex is an often-reported example of mutualism in the Neotropics. The ants colonize the hollow stems of their hosts, and in exchange, the plants benefit from a reduced degree of herbivory. The previous studies have shown that workers can discriminate their host from other plants, including a closely related species. Little is known about how queens locate their host during the colonization process, but it has been suggested that host recognition is mediated by volatiles. Since queens of Pseudomyrmex mordax colonize their hosts during the seedling stage, we hypothesized that queens would discriminate leaves of seedlings from adult plants. To evaluate our hypothesis, we used a two-sided olfactometer, to test the preference of queens towards different leaf and plant ages of Triplaris americana. Virgin queens of Pseudomyrmex mordax preferred seedlings over adult plants, as well as plant leaves over empty controls, showing no discrimination for leaf age. Our results suggest that the volatiles virgin queens recognize are either produced or are more abundant at the early growing stage of the host when colonization is crucial for the host's survival.
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Affiliation(s)
- María Fernanda Torres
- Ashworth Laboratories, Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
| | - Adriana Sanchez
- Programa de Biología, Universidad del Rosario, Carrera 24 No. 63C-69, Bogotá, Colombia
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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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Yoder JB, Leebens-Mack J. The evolutionary ecology of "mutual services" in the 21st century. AMERICAN JOURNAL OF BOTANY 2016; 103:1712-1716. [PMID: 27793857 DOI: 10.3732/ajb.1600367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 10/13/2016] [Indexed: 06/06/2023]
Affiliation(s)
- Jeremy B Yoder
- Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4 Canada
| | - James Leebens-Mack
- Department of Plant Biology, University of Georgia, Athens, Georgia 30602-7271 USA
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Fayle TM, Edwards DP, Turner EC, Dumbrell AJ, Eggleton P, Foster WA. Public goods, public services and by-product mutualism in an ant-fern symbiosis. OIKOS 2011. [DOI: 10.1111/j.1600-0706.2011.20062.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Archetti M, Ubeda F, Fudenberg D, Green J, Pierce NE, Yu DW. Let the right one in: a microeconomic approach to partner choice in mutualisms. Am Nat 2010; 177:75-85. [PMID: 21091210 DOI: 10.1086/657622] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
One of the main problems impeding the evolution of cooperation is partner choice. When information is asymmetric (the quality of a potential partner is known only to himself), it may seem that partner choice is not possible without signaling. Many mutualisms, however, exist without signaling, and the mechanisms by which hosts might select the right partners are unclear. Here we propose a general mechanism of partner choice, "screening," that is similar to the economic theory of mechanism design. Imposing the appropriate costs and rewards may induce the informed individuals to screen themselves according to their types and therefore allow a noninformed individual to establish associations with the correct partners in the absence of signaling. Several types of biological symbioses are good candidates for screening, including bobtail squid, ant-plants, gut microbiomes, and many animal and plant species that produce reactive oxygen species. We describe a series of diagnostic tests for screening. Screening games can apply to the cases where by-products, partner fidelity feedback, or host sanctions do not apply, therefore explaining the evolution of mutualism in systems where it is impossible for potential symbionts to signal their cooperativeness beforehand and where the host does not punish symbiont misbehavior.
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Affiliation(s)
- Marco Archetti
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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Abstract
Plants have evolved a range of strategies to manipulate the behaviour of their insect partners. One powerful strategy is to produce signals that already have a role in the animals' own communication systems. To investigate to what extent the evolution of floral scents is correlated with chemical communication in insects, I analyse the occurrence, commonness, and evolutionary patterns of the 71 most common 'floral' volatile organic compounds (VOCs) in 96 plant families and 87 insect families. I found an overlap of 87% in VOCs produced by plants and insects. 'Floral' monoterpenes showed strong positive correlation in commonness between plants (both gymnosperms and angiosperms) and herbivores, whereas the commonness of 'floral' aromatics was positively correlated between angiosperms and both pollinators and herbivores. According to a multivariate regression analysis the commonness of 'floral' aromatics was best explained by their commonness in pollinators, whereas monoterpenes were best explained by herbivores. Among pollinator orders, aromatics were significantly more common in Lepidoptera than in Hymenoptera, whereas monoterpenes showed no difference among the two orders. Collectively, these patterns suggest that plants and insects converge in overall patterns of volatile production, both for attraction and defence. Monoterpenes seem to have evolved primarily for defence under selection by herbivores, whereas aromatics evolved signalling functions in angiosperms, primarily for pollinator attraction.
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Affiliation(s)
- Florian P Schiestl
- Institute of Systematic Botany, Zollikerstrasse 107, University of Zürich, 8008 Zürich, Switzerland.
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Edwards DP, Ansell FA, Woodcock P, Fayle TM, Chey VK, Hamer KC. Can the failure to punish promote cheating in mutualism? OIKOS 2010. [DOI: 10.1111/j.1600-0706.2009.17591.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Wang RW, Ridley J, Sun BF, Zheng Q, Dunn DW, Cook J, Shi L, Zhang YP, Yu DW. Interference competition and high temperatures reduce the virulence of fig wasps and stabilize a fig-wasp mutualism. PLoS One 2009; 4:e7802. [PMID: 19915668 PMCID: PMC2771911 DOI: 10.1371/journal.pone.0007802] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Accepted: 10/15/2009] [Indexed: 11/19/2022] Open
Abstract
Fig trees are pollinated by fig wasps, which also oviposit in female flowers. The wasp larvae gall and eat developing seeds. Although fig trees benefit from allowing wasps to oviposit, because the wasp offspring disperse pollen, figs must prevent wasps from ovipositing in all flowers, or seed production would cease, and the mutualism would go extinct. In Ficus racemosa, we find that syconia ('figs') that have few foundresses (ovipositing wasps) are underexploited in the summer (few seeds, few galls, many empty ovules) and are overexploited in the winter (few seeds, many galls, few empty ovules). Conversely, syconia with many foundresses produce intermediate numbers of galls and seeds, regardless of season. We use experiments to explain these patterns, and thus, to explain how this mutualism is maintained. In the hot summer, wasps suffer short lifespans and therefore fail to oviposit in many flowers. In contrast, cooler temperatures in the winter permit longer wasp lifespans, which in turn allows most flowers to be exploited by the wasps. However, even in winter, only in syconia that happen to have few foundresses are most flowers turned into galls. In syconia with higher numbers of foundresses, interference competition reduces foundress lifespans, which reduces the proportion of flowers that are galled. We further show that syconia encourage the entry of multiple foundresses by delaying ostiole closure. Taken together, these factors allow fig trees to reduce galling in the wasp-benign winter and boost galling (and pollination) in the wasp-stressing summer. Interference competition has been shown to reduce virulence in pathogenic bacteria. Our results show that interference also maintains cooperation in a classic, cooperative symbiosis, thus linking theories of virulence and mutualism. More generally, our results reveal how frequency-dependent population regulation can occur in the fig-wasp mutualism, and how a host species can 'set the rules of the game' to ensure mutualistic behavior in its symbionts.
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Affiliation(s)
- Rui-Wu Wang
- Ecology, Conservation, and Environment Center (ECEC), State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Jo Ridley
- Centre for Ecology, Evolution and Conservation (CEEC) and School of Biological Sciences, University of East Anglia, Norwich, Norfolk, United Kingdom
| | - Bao-Fa Sun
- Ecology, Conservation, and Environment Center (ECEC), State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Qi Zheng
- Ecology, Conservation, and Environment Center (ECEC), State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Derek W. Dunn
- Centre for Ecology, Evolution and Conservation (CEEC) and School of Biological Sciences, University of East Anglia, Norwich, Norfolk, United Kingdom
- School of Biological Sciences, University of Reading, Reading, Berks, United Kingdom
| | - James Cook
- School of Biological Sciences, University of Reading, Reading, Berks, United Kingdom
| | - Lei Shi
- Statistics and Mathematics College, Yunnan University of Finance and Economics, Kunming, Yunnan, China
| | - Ya-Ping Zhang
- Ecology, Conservation, and Environment Center (ECEC), State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Douglas W. Yu
- Ecology, Conservation, and Environment Center (ECEC), State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Centre for Ecology, Evolution and Conservation (CEEC) and School of Biological Sciences, University of East Anglia, Norwich, Norfolk, United Kingdom
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Szilágyi A, Scheuring I, Edwards DP, Orivel J, Yu DW. The evolution of intermediate castration virulence and ant coexistence in a spatially structured environment. Ecol Lett 2009; 12:1306-16. [PMID: 19780787 DOI: 10.1111/j.1461-0248.2009.01382.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- András Szilágyi
- Department of Plant Taxonomy and Ecology, Eötvös University, Pázmány Péter sétány 1C, H-1117 Budapest, Hungary
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Debout GDG, Frederickson ME, Aron S, Yu DW. Unexplained split sex ratios in the neotropical plant-ant, Allomerus octoarticulatus var. demerarae (Myrmicinae): a test of hypotheses. Evolution 2009; 64:126-41. [PMID: 19703224 DOI: 10.1111/j.1558-5646.2009.00824.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We investigated sex allocation in the Neotropical ant Allomerus octoarticulatus var. demerarae. Because Allomerus is a plant symbiont, we could make geographically extensive collections of complete colonies and of foundresses in saplings, allowing us to estimate not only population- and colony-level sex allocation but also colony resource levels and the relatedness of competing ant foundresses. This species exhibits a strongly split sex ratio, with 80% of mature colonies producing >or=90% of one sex or the other. Our genetic analyses (DNA microsatellites) reveal that Allomerus has a breeding system characterized by almost complete monogyny and a low frequency of polyandry. Contrary to theoretical explanations, we find no difference in worker relatedness asymmetries between female- and male-specialist colonies. Furthermore, no clear link was found between colony sex allocation and life history traits such as the number of mates per queen, or colony size, resource level, or fecundity. We also failed to find significant support for male production by workers, infection by Wolbachia, local resource competition, or local mate competition. We are left with the possibility that Allomerus exhibits split sex ratios because of the evolution of alternative biasing strategies in queens or workers, as recently proposed in the literature.
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Affiliation(s)
- Gabriel D G Debout
- Ecology, Conservation, and Environment Center, State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Science, Kunming, Yunnan 65022, China
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Ranganathan Y, Borges RM. Predatory and trophobiont-tending ants respond differently to fig and fig wasp volatiles. Anim Behav 2009. [DOI: 10.1016/j.anbehav.2009.03.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Edwards DP. The roles of tolerance in the evolution, maintenance and breakdown of mutualism. Naturwissenschaften 2009; 96:1137-45. [PMID: 19484212 DOI: 10.1007/s00114-009-0559-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Revised: 04/20/2009] [Accepted: 05/13/2009] [Indexed: 10/20/2022]
Abstract
Tolerance strategies are cost-reduction mechanisms that enable organisms to recover some of the fitness lost to damage, but impose limited or no cost on antagonists. They are frequently invoked in studies of plant-herbivore and of host-parasite interactions, but the possible roles of tolerance in mutualism (interspecific cooperation) have yet to be thoroughly examined. This review identifies candidate roles for tolerance in the evolution, maintenance and breakdown of mutualism. Firstly, by reducing the cost of damage, tolerance provides a key pathway by which pre-mutualistic hosts can reduce the cost of association with their parasites, promoting cooperation. This holds for the evolution of 'evolved dependency' type mutualism, where a host requires an antagonist that does not direct any reward to their partner for some resource, and of 'outright mutualism', where participants directly trade benefits. Secondly, in outright mutualism, tolerance might maintain cooperation by reducing the cost of a persisting negative trait in a symbiotic partner. Finally, the evolution of tolerance might also provide a pathway out of mutualism because the host could evolve a cheaper alternative to continued cooperation with its mutualistic partner, permitting autonomy. A key consequence of tolerance is that it contrasts with partner choice mechanisms that impose large costs on cheats, and I highlight understanding any trade-off between tolerance and partner choice as an important research topic in the evolution of cooperation. I conclude by identifying tolerance as part of a more general phenomenon of co-adaptation in mutualism and parasitism that drives the evolution of the cost/benefit ratio from the interaction.
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Affiliation(s)
- David P Edwards
- Institute of Integrative and Comparative Biology, University of Leeds, Leeds, UK.
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16
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Indirect defense in a highly specific ant-plant mutualism. Naturwissenschaften 2008; 95:909-16. [PMID: 18496661 DOI: 10.1007/s00114-008-0398-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 04/24/2008] [Accepted: 04/29/2008] [Indexed: 10/22/2022]
Abstract
Although associations between myrmecophytes and their plant ants are recognized as a particularly effective form of protective mutualism, their functioning remains incompletely understood. This field study examined the ant-plant Hirtella physophora and its obligate ant associate Allomerus decemarticulatus. We formulated two hypotheses on the highly specific nature of this association: (1) Ant presence should be correlated with a marked reduction in the amount of herbivory on the plant foliage; (2) ant activity should be consistent with the "optimal defense" theory predicting that the most vulnerable and valuable parts of the plant are the best defended. We validated the first hypothesis by demonstrating that for ant-excluded plants, expanding leaves, but also newly matured ones in the long term, suffered significantly more herbivore damage than ant-inhabited plants. We showed that A. decemarticulatus workers represent both constitutive and inducible defenses for their host, by patrolling its foliage and rapidly recruiting nestmates to foliar wounds. On examining how these activities change according to the leaves' developmental stage, we found that the number of patrolling ants dramatically decreased as the leaves matured, while leaf wounds induced ant recruitment regardless of the leaf's age. The resulting level of these indirect defenses was roughly proportional to leaf vulnerability and value during its development, thus validating our second hypothesis predicting optimal protection. This led us to discuss the factors influencing ant activity on the plant's surface. Our study emphasizes the importance of studying both the constitutive and inducible components of indirect defense when evaluating its efficacy and optimality.
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