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Picciotti U, Araujo Dalbon V, Ciancio A, Colagiero M, Cozzi G, De Bellis L, Finetti-Sialer MM, Greco D, Ippolito A, Lahbib N, Logrieco AF, López-Llorca LV, Lopez-Moya F, Luvisi A, Mincuzzi A, Molina-Acevedo JP, Pazzani C, Scortichini M, Scrascia M, Valenzano D, Garganese F, Porcelli F. "Ectomosphere": Insects and Microorganism Interactions. Microorganisms 2023; 11:microorganisms11020440. [PMID: 36838405 PMCID: PMC9967823 DOI: 10.3390/microorganisms11020440] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 01/30/2023] [Accepted: 02/06/2023] [Indexed: 02/12/2023] Open
Abstract
This study focuses on interacting with insects and their ectosymbiont (lato sensu) microorganisms for environmentally safe plant production and protection. Some cases help compare ectosymbiont microorganisms that are insect-borne, -driven, or -spread relevant to endosymbionts' behaviour. Ectosymbiotic bacteria can interact with insects by allowing them to improve the value of their pabula. In addition, some bacteria are essential for creating ecological niches that can host the development of pests. Insect-borne plant pathogens include bacteria, viruses, and fungi. These pathogens interact with their vectors to enhance reciprocal fitness. Knowing vector-phoront interaction could considerably increase chances for outbreak management, notably when sustained by quarantine vector ectosymbiont pathogens, such as the actual Xylella fastidiosa Mediterranean invasion episode. Insect pathogenic viruses have a close evolutionary relationship with their hosts, also being highly specific and obligate parasites. Sixteen virus families have been reported to infect insects and may be involved in the biological control of specific pests, including some economic weevils. Insects and fungi are among the most widespread organisms in nature and interact with each other, establishing symbiotic relationships ranging from mutualism to antagonism. The associations can influence the extent to which interacting organisms can exert their effects on plants and the proper management practices. Sustainable pest management also relies on entomopathogenic fungi; research on these species starts from their isolation from insect carcasses, followed by identification using conventional light or electron microscopy techniques. Thanks to the development of omics sciences, it is possible to identify entomopathogenic fungi with evolutionary histories that are less-shared with the target insect and can be proposed as pest antagonists. Many interesting omics can help detect the presence of entomopathogens in different natural matrices, such as soil or plants. The same techniques will help localize ectosymbionts, localization of recesses, or specialized morphological adaptation, greatly supporting the robust interpretation of the symbiont role. The manipulation and modulation of ectosymbionts could be a more promising way to counteract pests and borne pathogens, mitigating the impact of formulates and reducing food insecurity due to the lesser impact of direct damage and diseases. The promise has a preventive intent for more manageable and broader implications for pests, comparing what we can obtain using simpler, less-specific techniques and a less comprehensive approach to Integrated Pest Management (IPM).
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Affiliation(s)
- Ugo Picciotti
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, University of Bari Aldo Moro, 70126 Bari, Italy
- Department of Marine Science and Applied Biology, University of Alicante, 03690 Alicante, Spain
| | | | - Aurelio Ciancio
- Institute for Sustainable Plant Protection, National Research Council (CNR), Via G. Amendola 122/D, 70126 Bari, Italy
| | - Mariantonietta Colagiero
- Institute for Sustainable Plant Protection, National Research Council (CNR), Via G. Amendola 122/D, 70126 Bari, Italy
| | - Giuseppe Cozzi
- Institute of Food Production Sciences, National Research Council (CNR), Via G. Amendola 122/O, 70126 Bari, Italy
| | - Luigi De Bellis
- Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy
| | | | - Davide Greco
- Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy
| | - Antonio Ippolito
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, University of Bari Aldo Moro, 70126 Bari, Italy
| | - Nada Lahbib
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, University of Bari Aldo Moro, 70126 Bari, Italy
- Faculty of Sciences of Tunis, University of Tunis El-Manar, Tunis 1002, Tunisia
| | - Antonio Francesco Logrieco
- Institute of Food Production Sciences, National Research Council (CNR), Via G. Amendola 122/O, 70126 Bari, Italy
| | | | - Federico Lopez-Moya
- Department of Marine Science and Applied Biology, University of Alicante, 03690 Alicante, Spain
| | - Andrea Luvisi
- Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy
| | - Annamaria Mincuzzi
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, University of Bari Aldo Moro, 70126 Bari, Italy
| | - Juan Pablo Molina-Acevedo
- Colombian Corporation for Agricultural Research Agrosavia C. I. Turipana-AGROSAVIA, Km. 13, Vía Montería-Cereté 230558, Colombia
| | - Carlo Pazzani
- Dipartimento di Bioscienze, Biotecnologie e Ambiente (DBBA), University of Bari Aldo Moro, 70126 Bari, Italy
| | - Marco Scortichini
- Research Centre for Olive, Fruit and Citrus Crops, Council for Agricultural Research and Economics (CREA), 00134 Roma, Italy
| | - Maria Scrascia
- Dipartimento di Bioscienze, Biotecnologie e Ambiente (DBBA), University of Bari Aldo Moro, 70126 Bari, Italy
| | - Domenico Valenzano
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, University of Bari Aldo Moro, 70126 Bari, Italy
| | - Francesca Garganese
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, University of Bari Aldo Moro, 70126 Bari, Italy
- Correspondence:
| | - Francesco Porcelli
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, University of Bari Aldo Moro, 70126 Bari, Italy
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Barrett BT, Kubik TD, Golightly PR, Kellner K, Kardish MR, Mueller UG. Ant genotype, but not genotype of cultivated fungi, predicts queen acceptance in the asexual fungus-farming ant Mycocepurus smithii (Hymenoptera: Formicidae). Behav Ecol Sociobiol 2023. [DOI: 10.1007/s00265-022-03276-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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3
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Beigel K, Matthews AE, Kellner K, Pawlik CV, Greenwold M, Seal JN. Cophylogenetic analyses of Trachymyrmex ant-fungal specificity: "One to one with some exceptions". Mol Ecol 2021; 30:5605-5620. [PMID: 34424571 DOI: 10.1111/mec.16140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 08/05/2021] [Accepted: 08/11/2021] [Indexed: 01/18/2023]
Abstract
Over the past few decades, large-scale phylogenetic analyses of fungus-gardening ants and their symbiotic fungi have depicted strong concordance among major clades of ants and their symbiotic fungi, yet within clades, fungus sharing is widespread among unrelated ant lineages. Sharing has been explained using a diffuse coevolution model within major clades. Understanding horizontal exchange within clades has been limited by conventional genetic markers that lack both interspecific and geographic variation. To examine whether reports of horizontal exchange were indeed due to symbiont sharing or the result of employing relatively uninformative molecular markers, samples of Trachymyrmex arizonensis and Trachymyrmex pomonae and their fungi were collected from native populations in Arizona and genotyped using conventional marker genes and genome-wide single nucleotide polymorphisms (SNPs). Conventional markers of the fungal symbionts generally exhibited cophylogenetic patterns that were consistent with some symbiont sharing, but most fungal clades had low support. SNP analysis, in contrast, indicated that each ant species exhibited fidelity to its own fungal subclade with only one instance of a colony growing a fungus that was otherwise associated with a different ant species. This evidence supports a pattern of codivergence between Trachymyrmex species and their fungi, and thus a diffuse coevolutionary model may not accurately predict symbiont exchange. These results suggest that fungal sharing across host species in these symbioses may be less extensive than previously thought.
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Affiliation(s)
- Katherine Beigel
- Department of Biology, The University of Texas at Tyler, Tyler, Texas, USA
| | - Alix E Matthews
- Department of Biology, The University of Texas at Tyler, Tyler, Texas, USA.,College of Sciences and Mathematics and Molecular Biosciences Program, Arkansas State University, Jonesboro, Arkansas, USA
| | - Katrin Kellner
- Department of Biology, The University of Texas at Tyler, Tyler, Texas, USA
| | - Christine V Pawlik
- Department of Biology, The University of Texas at Tyler, Tyler, Texas, USA
| | - Matthew Greenwold
- Department of Biology, The University of Texas at Tyler, Tyler, Texas, USA
| | - Jon N Seal
- Department of Biology, The University of Texas at Tyler, Tyler, Texas, USA
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4
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Matthews AE, Kellner K, Seal JN. Male-biased dispersal in a fungus-gardening ant symbiosis. Ecol Evol 2021; 11:2307-2320. [PMID: 33717457 PMCID: PMC7920773 DOI: 10.1002/ece3.7198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 12/08/2020] [Accepted: 12/11/2020] [Indexed: 02/06/2023] Open
Abstract
For nearly all organisms, dispersal is a fundamental life-history trait that can shape their ecology and evolution. Variation in dispersal capabilities within a species exists and can influence population genetic structure and ecological interactions. In fungus-gardening (attine) ants, co-dispersal of ants and mutualistic fungi is crucial to the success of this obligate symbiosis. Female-biased dispersal (and gene flow) may be favored in attines because virgin queens carry the responsibility of dispersing the fungi, but a paucity of research has made this conclusion difficult. Here, we investigate dispersal of the fungus-gardening ant Trachymyrmex septentrionalis using a combination of maternally (mitochondrial DNA) and biparentally inherited (microsatellites) markers. We found three distinct, spatially isolated mitochondrial DNA haplotypes; two were found in the Florida panhandle and the other in the Florida peninsula. In contrast, biparental markers illustrated significant gene flow across this region and minimal spatial structure. The differential patterns uncovered from mitochondrial DNA and microsatellite markers suggest that most long-distance ant dispersal is male-biased and that females (and concomitantly the fungus) have more limited dispersal capabilities. Consequently, the limited female dispersal is likely an important bottleneck for the fungal symbiont. This bottleneck could slow fungal genetic diversification, which has significant implications for both ant hosts and fungal symbionts regarding population genetics, species distributions, adaptive responses to environmental change, and coevolutionary patterns.
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Affiliation(s)
- Alix E. Matthews
- Department of BiologyThe University of Texas at TylerTylerTXUSA
- Present address:
College of Sciences and Mathematics and Molecular Biosciences ProgramArkansas State UniversityJonesboroARUSA
| | - Katrin Kellner
- Department of BiologyThe University of Texas at TylerTylerTXUSA
| | - Jon N. Seal
- Department of BiologyThe University of Texas at TylerTylerTXUSA
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5
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Shik JZ, Kooij PW, Donoso DA, Santos JC, Gomez EB, Franco M, Crumière AJJ, Arnan X, Howe J, Wcislo WT, Boomsma JJ. Nutritional niches reveal fundamental domestication trade-offs in fungus-farming ants. Nat Ecol Evol 2020; 5:122-134. [PMID: 33106603 PMCID: PMC7610523 DOI: 10.1038/s41559-020-01314-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 08/25/2020] [Indexed: 02/06/2023]
Abstract
During crop domestication, human farmers traded greater productivity for higher crop vulnerability outside specialized cultivation conditions. We found a similar domestication tradeoff across the major co-evolutionary transitions in farming systems of attine ants. First, the fundamental nutritional niches (FNNs) of cultivars narrowed during ~ 60 million years of naturally selected domestication, and laboratory experiments showed that ant farmers representing subsequent domestication stages strictly regulate protein harvest relative to cultivar FNNs. Second, ants with different farming systems differed in their abilities to harvest the resources that best matched the nutritional needs of their fungal cultivars. This was assessed by quantifying realized nutritional niches (RNNs) from analyses of items collected from the mandibles of laden ant foragers in the field. Third, extensive field collections suggest that among-colony genetic diversity of cultivars in small-scale farms may offer population-wide resilience benefits that species with large-scale farming colonies achieve by more elaborate and demanding cultivation practices of less diverse crops. Our results underscore that naturally selected farming systems have potential to shed light on nutritional tradeoffs that shaped the course of culturally evolved human farming.
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Affiliation(s)
- Jonathan Z Shik
- Section of Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark. .,Centre for Social Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark. .,Smithsonian Tropical Research Institute, Panama City, Republic of Panama.
| | - Pepijn W Kooij
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark.,Comparative Fungal Biology, Department of Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, London, UK.,Center for the Study of Social Insects, São Paulo State University (UNESP), Rio Claro, Brazil
| | - David A Donoso
- Departamento de Biología, Escuela Politécnica Nacional, Quito, Ecuador.,Centro de Investigación de la Biodiversidad y Cambio Climático, Universidad Tecnológica Indoamérica, Quito, Ecuador
| | - Juan C Santos
- Department of Biological Sciences, St. John's University, New York, NY, USA
| | - Ernesto B Gomez
- Smithsonian Tropical Research Institute, Panama City, Republic of Panama
| | - Mariana Franco
- Smithsonian Tropical Research Institute, Panama City, Republic of Panama
| | - Antonin J J Crumière
- Section of Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Xavier Arnan
- Centre de Recerca Ecològica i Aplicacions Forestals (CREAF), Cerdanyola del Vallès, Spain.,Department of Biological Sciences, University of Pernambuco, Garanhuns, Brazil
| | - Jack Howe
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark.,Department of Zoology, University of Oxford, Oxford, UK
| | - William T Wcislo
- Smithsonian Tropical Research Institute, Panama City, Republic of Panama
| | - Jacobus J Boomsma
- Section of Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark.,Centre for Social Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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6
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Bizarria R, Nagamoto NS, Rodrigues A. Lack of fungal cultivar fidelity and low virulence of Escovopsis trichodermoides. FUNGAL ECOL 2020. [DOI: 10.1016/j.funeco.2020.100944] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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7
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High diversity and multiple invasions to North America by fungi grown by the northern-most Trachymyrmex and Mycetomoellerius ant species. FUNGAL ECOL 2020. [DOI: 10.1016/j.funeco.2019.100878] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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8
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Matthews AE, Rowan C, Stone C, Kellner K, Seal JN. Development, characterization, and cross-amplification of polymorphic microsatellite markers for North American Trachymyrmex and Mycetomoellerius ants. BMC Res Notes 2020; 13:173. [PMID: 32204727 PMCID: PMC7092486 DOI: 10.1186/s13104-020-05015-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 03/11/2020] [Indexed: 01/19/2023] Open
Abstract
Objective The objective of this study is to develop and identify polymorphic microsatellite markers for fungus-gardening (attine) ants in the genus Trachymyrmex sensu lato. These ants are important ecosystem engineers and have been a model group for understanding complex symbiotic systems, but very little is understood about the intraspecific genetic patterns across most North American attine species. These microsatellite markers will help to better study intraspecific population genetic structure, gene flow, mating habits, and phylogeographic patterns in these species and potentially other congeners. Results Using next-generation sequencing techniques, we identified 17 and 12 polymorphic microsatellite markers from T. septentrionalis and Mycetomoellerius (formerly Trachymyrmex) turrifex, respectively, and assessed the genetic diversity of each marker. We also analyzed the cross-amplification success of the T. septentrionalis markers in two other closely related Trachymyrmex species, and identified 10 and 12 polymorphic markers for T. arizonensis and T. pomonae, respectively.
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Affiliation(s)
- Alix E Matthews
- Department of Biology, The University of Texas at Tyler, Tyler, TX, USA
| | - Chase Rowan
- Department of Biology, The University of Texas at Tyler, Tyler, TX, USA
| | - Colby Stone
- Department of Biology, The University of Texas at Tyler, Tyler, TX, USA
| | - Katrin Kellner
- Department of Biology, The University of Texas at Tyler, Tyler, TX, USA
| | - Jon N Seal
- Department of Biology, The University of Texas at Tyler, Tyler, TX, USA.
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9
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Marshall RC, Whitworth DE. Is "Wolf-Pack" Predation by Antimicrobial Bacteria Cooperative? Cell Behaviour and Predatory Mechanisms Indicate Profound Selfishness, Even when Working Alongside Kin. Bioessays 2019; 41:e1800247. [PMID: 30919490 DOI: 10.1002/bies.201800247] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 02/10/2019] [Indexed: 01/27/2023]
Abstract
For decades, myxobacteria have been spotlighted as exemplars of social "wolf-pack" predation, communally secreting antimicrobial substances into the shared public milieu. This behavior has been described as cooperative, becoming more efficient if performed by more cells. However, laboratory evidence for cooperativity is limited and of little relevance to predation in a natural setting. In contrast, there is accumulating evidence for predatory mechanisms promoting "selfish" behavior during predation, which together with conflicting definitions of cooperativity, casts doubt on whether microbial "wolf-pack" predation really is cooperative. Here, it is hypothesized that public-goods-mediated predation is not cooperative, and it is argued that a holistic model of microbial predation is needed, accounting for predator and prey relatedness, social phenotypes, spatial organization, activity/specificity/transport of secreted toxins, and prey resistance mechanisms. Filling such gaps in our knowledge is vital if the evolutionary benefits of potentially costly microbial behaviors mediated by public goods are to be properly understood.
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Affiliation(s)
- Rupert C Marshall
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, Ceredigion SY23 3DA, UK
| | - David E Whitworth
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, Ceredigion SY23 3DA, UK
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10
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Meta-Omics Tools in the World of Insect-Microorganism Interactions. BIOLOGY 2018; 7:biology7040050. [PMID: 30486337 PMCID: PMC6316257 DOI: 10.3390/biology7040050] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/16/2018] [Accepted: 11/22/2018] [Indexed: 02/07/2023]
Abstract
Microorganisms are able to influence several aspects of insects’ life, and this statement is gaining increasing strength, as research demonstrates it daily. At the same time, new sequencing technologies are now available at a lower cost per base, and bioinformatic procedures are becoming more user-friendly. This is triggering a huge effort in studying the microbial diversity associated to insects, and especially to economically important insect pests. The importance of the microbiome has been widely acknowledged for a wide range of animals, and also for insects this topic is gaining considerable importance. In addition to bacterial-associates, the insect-associated fungal communities are also gaining attention, especially those including plant pathogens. The use of meta-omics tools is not restricted to the description of the microbial world, but it can be also used in bio-surveillance, food safety assessment, or even to bring novelties to the industry. This mini-review aims to give a wide overview of how meta-omics tools are fostering advances in research on insect-microorganism interactions.
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11
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Kellner K, Kardish MR, Seal JN, Linksvayer TA, Mueller UG. Symbiont-Mediated Host-Parasite Dynamics in a Fungus-Gardening Ant. MICROBIAL ECOLOGY 2018; 76:530-543. [PMID: 29285550 DOI: 10.1007/s00248-017-1124-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 12/01/2017] [Indexed: 06/07/2023]
Abstract
Group-living can promote the evolution of adaptive strategies to prevent and control disease. Fungus-gardening ants must cope with two sets of pathogens, those that afflict the ants themselves and those of their symbiotic fungal gardens. While much research has demonstrated the impact of specialized fungal pathogens that infect ant fungus gardens, most of these studies focused on the so-called higher attine ants, which are thought to coevolve diffusely with two clades of leucocoprinaceous fungi. Relatively few studies have addressed disease ecology of lower Attini, which are thought to occasionally recruit (domesticate) novel leucocoprinaceous fungi from free-living populations; coevolution between lower-attine ants and their fungi is therefore likely weaker (or even absent) than in the higher Attini, which generally have many derived modifications. Toward understanding the disease ecology of lower-attine ants, this study (a) describes the diversity in the microfungal genus Escovopsis that naturally infect fungus gardens of the lower-attine ant Mycocepurus smithii and (b) experimentally determines the relative contributions of Escovopsis strain (a possible garden disease), M. smithii ant genotype, and fungal cultivar lineage to disease susceptibility and colony fitness. In controlled in-vivo infection laboratory experiments, we demonstrate that the susceptibility to Escovopsis infection was an outcome of ant-cultivar-Escovopsis interaction, rather than solely due to ant genotype or fungal cultivar lineage. The role of complex ant-cultivar-Escovopsis interactions suggests that switching M. smithii farmers onto novel fungus types might be a strategy to generate novel ant-fungus combinations resistant to most, but perhaps not all, Escovopsis strains circulating in a local population of this and other lower-attine ants.
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Affiliation(s)
- Katrin Kellner
- Section of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA.
- Department of Biology, University of Texas at Tyler, Tyler, TX, 75799, USA.
| | - M R Kardish
- Section of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
- Deptartment of Evolution and Ecology, University of California, Davis, CA, 95616, USA
| | - J N Seal
- Section of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
- Department of Biology, University of Texas at Tyler, Tyler, TX, 75799, USA
| | - T A Linksvayer
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - U G Mueller
- Section of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
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12
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Urbini L, Sinaimeri B, Matias C, Sagot MF. Exploring the Robustness of the Parsimonious Reconciliation Method in Host-Symbiont Cophylogeny. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2018; 16:738-748. [PMID: 29993554 DOI: 10.1109/tcbb.2018.2838667] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The aim of this paper is to explore the robustness of the parsimonious host-symbiont tree reconciliation method under editing or small perturbations of the input. The editing involves making different choices of unique symbiont mapping to a host in the case where multiple associations exist. This is made necessary by the fact that the tree reconciliation model is currently unable to handle such associations. The analysis performed could however also address the problem of errors. The perturbations are re-rootings of the symbiont tree to deal with a possibly wrong placement of the root specially in the case of fast-evolving species. In order to do this robustness analysis, we introduce a simulation scheme specifically designed for the host-symbiont cophylogeny context, as well as a measure to compare sets of tree reconciliations, both of which are of interest by themselves.
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13
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Mueller UG, Kardish MR, Ishak HD, Wright AM, Solomon SE, Bruschi SM, Carlson AL, Bacci M. Phylogenetic patterns of ant-fungus associations indicate that farming strategies, not only a superior fungal cultivar, explain the ecological success of leafcutter ants. Mol Ecol 2018; 27:2414-2434. [PMID: 29740906 DOI: 10.1111/mec.14588] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 03/13/2018] [Accepted: 03/14/2018] [Indexed: 01/18/2023]
Abstract
To elucidate fungicultural specializations contributing to ecological dominance of leafcutter ants, we estimate the phylogeny of fungi cultivated by fungus-growing (attine) ants, including fungal cultivars from (i) the entire leafcutter range from southern South America to southern North America, (ii) all higher-attine ant lineages (leafcutting genera Atta, Acromyrmex; nonleafcutting genera Trachymyrmex, Sericomyrmex) and (iii) all lower-attine lineages. Higher-attine fungi form two clades, Clade-A fungi (Leucocoprinus gongylophorus, formerly Attamyces) previously thought to be cultivated only by leafcutter ants, and a sister clade, Clade-B fungi, previously thought to be cultivated only by Trachymyrmex and Sericomyrmex ants. Contradicting this traditional view, we find that (i) leafcutter ants are not specialized to cultivate only Clade-A fungi because some leafcutter species ranging across South America cultivate Clade-B fungi; (ii) Trachymyrmex ants are not specialized to cultivate only Clade-B fungi because some Trachymyrmex species cultivate Clade-A fungi and other Trachymyrmex species cultivate fungi known so far only from lower-attine ants; (iii) in some locations, single higher-attine ant species or closely related cryptic species cultivate both Clade-A and Clade-B fungi; and (iv) ant-fungus co-evolution among higher-attine mutualisms is therefore less specialized than previously thought. Sympatric leafcutter ants can be ecologically dominant when cultivating either Clade-A or Clade-B fungi, sustaining with either cultivar-type huge nests that command large foraging territories; conversely, sympatric Trachymyrmex ants cultivating either Clade-A or Clade-B fungi can be locally abundant without achieving the ecological dominance of leafcutter ants. Ecological dominance of leafcutter ants therefore does not depend primarily on specialized fungiculture of L. gongylophorus (Clade-A), but must derive from ant-fungus synergisms and unique ant adaptations.
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Affiliation(s)
- Ulrich G Mueller
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas
| | - Melissa R Kardish
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas.,Center for Population Biology, University of California, Davis, California
| | - Heather D Ishak
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas.,Department of Medicine, Stanford University, Stanford, California
| | - April M Wright
- Department of Biological Science, Southeastern Louisiana University, Hammond, Louisiana
| | - Scott E Solomon
- Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas.,Department of Entomology, Smithsonian Institution, Washington, District of Columbia
| | - Sofia M Bruschi
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas.,Centro de Estudos de Insetos Sociais, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil
| | - Alexis L Carlson
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas
| | - Maurício Bacci
- Centro de Estudos de Insetos Sociais, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil
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Mueller UG, Ishak HD, Bruschi SM, Smith CC, Herman JJ, Solomon SE, Mikheyev AS, Rabeling C, Scott JJ, Cooper M, Rodrigues A, Ortiz A, Brandão CRF, Lattke JE, Pagnocca FC, Rehner SA, Schultz TR, Vasconcelos HL, Adams RMM, Bollazzi M, Clark RM, Himler AG, LaPolla JS, Leal IR, Johnson RA, Roces F, Sosa-Calvo J, Wirth R, Bacci M. Biogeography of mutualistic fungi cultivated by leafcutter ants. Mol Ecol 2017; 26:6921-6937. [PMID: 29134724 DOI: 10.1111/mec.14431] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 09/19/2017] [Accepted: 10/04/2017] [Indexed: 01/03/2023]
Abstract
Leafcutter ants propagate co-evolving fungi for food. The nearly 50 species of leafcutter ants (Atta, Acromyrmex) range from Argentina to the United States, with the greatest species diversity in southern South America. We elucidate the biogeography of fungi cultivated by leafcutter ants using DNA sequence and microsatellite-marker analyses of 474 cultivars collected across the leafcutter range. Fungal cultivars belong to two clades (Clade-A and Clade-B). The dominant and widespread Clade-A cultivars form three genotype clusters, with their relative prevalence corresponding to southern South America, northern South America, Central and North America. Admixture between Clade-A populations supports genetic exchange within a single species, Leucocoprinus gongylophorus. Some leafcutter species that cut grass as fungicultural substrate are specialized to cultivate Clade-B fungi, whereas leafcutters preferring dicot plants appear specialized on Clade-A fungi. Cultivar sharing between sympatric leafcutter species occurs frequently such that cultivars of Atta are not distinct from those of Acromyrmex. Leafcutters specialized on Clade-B fungi occur only in South America. Diversity of Clade-A fungi is greatest in South America, but minimal in Central and North America. Maximum cultivar diversity in South America is predicted by the Kusnezov-Fowler hypothesis that leafcutter ants originated in subtropical South America and only dicot-specialized leafcutter ants migrated out of South America, but the cultivar diversity becomes also compatible with a recently proposed hypothesis of a Central American origin by postulating that leafcutter ants acquired novel cultivars many times from other nonleafcutter fungus-growing ants during their migrations from Central America across South America. We evaluate these biogeographic hypotheses in the light of estimated dates for the origins of leafcutter ants and their cultivars.
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Affiliation(s)
- Ulrich G Mueller
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Heather D Ishak
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Sofia M Bruschi
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA.,Centro de Estudos de Insetos Sociais, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil
| | - Chad C Smith
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Jacob J Herman
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Scott E Solomon
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA.,Centro de Estudos de Insetos Sociais, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil.,Department of Ecology & Evolutionary Biology, Rice University, Houston, TX, USA
| | - Alexander S Mikheyev
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA.,Okinawa Institute of Science & Technology, Kunigami, Okinawa, Japan
| | - Christian Rabeling
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA.,School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Jarrod J Scott
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Michael Cooper
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Andre Rodrigues
- Centro de Estudos de Insetos Sociais, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil
| | - Adriana Ortiz
- Universidad Nacional de Colombia, Medellin, Colombia
| | | | - John E Lattke
- Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, Brazil
| | - Fernando C Pagnocca
- Centro de Estudos de Insetos Sociais, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil
| | - Stephen A Rehner
- Mycology and Nematology Genomic Diversity and Biology Laboratory, Beltsville, MD, USA
| | - Ted R Schultz
- Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | | | - Rachelle M M Adams
- Department of Evolution, Ecology & Organismal Biology, Museum of Biological Diversity, Columbus, OH, USA
| | - Martin Bollazzi
- Section of Entomology, Universidad de la República, Montevideo, Uruguay
| | - Rebecca M Clark
- Integrative Biology, University of California-Berkeley, Berkeley, CA, USA
| | - Anna G Himler
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA.,Department of Biology, College of Idaho, Caldwell, ID, USA
| | - John S LaPolla
- Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.,Department of Biological Sciences, Towson University, Towson, MD, USA
| | - Inara R Leal
- Departamento de Botânica, Universidade Federal de Pernambuco, Recife, PE, Brazil
| | - Robert A Johnson
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Flavio Roces
- Department of Behavioral Physiology and Sociobiology, Biozentrum, University of Würzburg, Würzburg, Germany
| | | | - Rainer Wirth
- Department of Plant Ecology and Systematics, University of Kaiserslautern, Kaiserslautern, Germany
| | - Maurício Bacci
- Centro de Estudos de Insetos Sociais, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil
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15
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Hogan CT, Jones TH, Zhukova M, Sosa-Calvo J, Adams RM. Novel mandibular gland volatiles from Apterostigma ants. BIOCHEM SYST ECOL 2017. [DOI: 10.1016/j.bse.2017.04.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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16
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Malacrinò A, Schena L, Campolo O, Laudani F, Palmeri V. Molecular analysis of the fungal microbiome associated with the olive fruit fly Bactrocera oleae. FUNGAL ECOL 2015. [DOI: 10.1016/j.funeco.2015.08.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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17
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Meirelles LA, Solomon SE, Bacci M, Wright AM, Mueller UG, Rodrigues A. Shared Escovopsis parasites between leaf-cutting and non-leaf-cutting ants in the higher attine fungus-growing ant symbiosis. ROYAL SOCIETY OPEN SCIENCE 2015; 2:150257. [PMID: 26473050 PMCID: PMC4593684 DOI: 10.1098/rsos.150257] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 09/07/2015] [Indexed: 05/31/2023]
Abstract
Fungus-gardening (attine) ants grow fungus for food in protected gardens, which contain beneficial, auxiliary microbes, but also microbes harmful to gardens. Among these potentially pathogenic microorganisms, the most consistently isolated are fungi in the genus Escovopsis, which are thought to co-evolve with ants and their cultivar in a tripartite model. To test clade-to-clade correspondence between Escovopsis and ants in the higher attine symbiosis (including leaf-cutting and non-leaf-cutting ants), we amassed a geographically comprehensive collection of Escovopsis from Mexico to southern Brazil, and reconstructed the corresponding Escovopsis phylogeny. Contrary to previous analyses reporting phylogenetic divergence between Escovopsis from leafcutters and Trachymyrmex ants (non-leafcutter), we found no evidence for such specialization; rather, gardens from leafcutters and non-leafcutters genera can sometimes be infected by closely related strains of Escovopsis, suggesting switches at higher phylogenetic levels than previously reported within the higher attine symbiosis. Analyses identified rare Escovopsis strains that might represent biogeographically restricted endemic species. Phylogenetic patterns correspond to morphological variation of vesicle type (hyphal structures supporting spore-bearing cells), separating Escovopsis with phylogenetically derived cylindrical vesicles from ancestral Escovopsis with globose vesicles. The new phylogenetic insights provide an improved basis for future taxonomic and ecological studies of Escovopsis.
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Affiliation(s)
- Lucas A. Meirelles
- Department of Biochemistry and Microbiology, UNESP—São Paulo State University, Rio Claro, São Paulo, Brazil
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | | | - Mauricio Bacci
- Center for the Study of Social Insects, UNESP—São Paulo State University, Rio Claro, São Paulo, Brazil
| | - April M. Wright
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Ulrich G. Mueller
- Department of Biochemistry and Microbiology, UNESP—São Paulo State University, Rio Claro, São Paulo, Brazil
| | - Andre Rodrigues
- Department of Biochemistry and Microbiology, UNESP—São Paulo State University, Rio Claro, São Paulo, Brazil
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18
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Kellner K, Ishak HD, Linksvayer TA, Mueller UG. Bacterial community composition and diversity in an ancestral ant fungus symbiosis. FEMS Microbiol Ecol 2015; 91:fiv073. [PMID: 26113689 DOI: 10.1093/femsec/fiv073] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2015] [Indexed: 12/16/2022] Open
Abstract
Fungus-farming ants (Hymenoptera: Formicidae, Attini) exhibit some of the most complex microbial symbioses because both macroscopic partners (ants and fungus) are associated with a rich community of microorganisms. The ant and fungal microbiomes are thought to serve important beneficial nutritional and defensive roles in these symbioses. While most recent research has investigated the bacterial communities in the higher attines (e.g. the leaf-cutter ant genera Atta and Acromyrmex), which are often associated with antibiotic-producing Actinobacteria, very little is known about the microbial communities in basal lineages, labeled as 'lower attines', which retain the ancestral traits of smaller and more simple societies. In this study, we used 16S amplicon pyrosequencing to characterize bacterial communities of the lower attine ant Mycocepurus smithii among seven sampling sites in central Panama. We discovered that ant and fungus garden-associated microbiota were distinct from surrounding soil, but unlike the situation in the derived fungus-gardening ants, which show distinct ant and fungal microbiomes, microbial community structure of the ants and their fungi were similar. Another surprising finding was that the abundance of actinomycete bacteria was low and instead, these symbioses were characterized by an abundance of Lactobacillus and Pantoea bacteria. Furthermore, our data indicate that Lactobacillus strains are acquired from the environment rather than acquired vertically.
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Affiliation(s)
- Katrin Kellner
- Section of Integrative Biology, Patterson Laboratories, University of Texas at Austin, 1 University Station #C0930, Austin, TX 78712, USA
| | - Heather D Ishak
- Section of Integrative Biology, Patterson Laboratories, University of Texas at Austin, 1 University Station #C0930, Austin, TX 78712, USA Division of Infectious Disease and Geographic Medicine, Stanford University, 300 Pasteur Dr. MC 5107, Stanford, CA 94305, USA
| | - Timothy A Linksvayer
- Department of Biology, University of Pennsylvania, 433 S. University Ave., Philadelphia, PA 19104, USA
| | - Ulrich G Mueller
- Section of Integrative Biology, Patterson Laboratories, University of Texas at Austin, 1 University Station #C0930, Austin, TX 78712, USA
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De Fine Licht HH, Boomsma JJ. Variable interaction specificity and symbiont performance in Panamanian Trachymyrmex and Sericomyrmex fungus-growing ants. BMC Evol Biol 2014; 14:244. [PMID: 25471204 PMCID: PMC4262973 DOI: 10.1186/s12862-014-0244-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 11/14/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cooperative benefits of mutualistic interactions are affected by genetic variation among the interacting partners, which may have consequences for interaction-specificities across guilds of sympatric species with similar mutualistic life histories. The gardens of fungus-growing (attine) ants produce carbohydrate active enzymes that degrade plant material collected by the ants and offer them food in exchange. The spectrum of these enzyme activities is an important symbiont service to the host but may vary among cultivar genotypes. The sympatric occurrence of several Trachymyrmex and Sericomyrmex higher attine ants in Gamboa, Panama provided the opportunity to do a quantitative study of species-level interaction-specificity. RESULTS We genotyped the ants for Cytochrome Oxidase and their Leucoagaricus fungal cultivars for ITS rDNA. Combined with activity measurements for 12 carbohydrate active enzymes, these data allowed us to test whether garden enzyme activity was affected by fungal strain, farming ants or combinations of the two. We detected two cryptic ant species, raising ant species number from four to six, and we show that the 38 sampled colonies reared a total of seven fungal haplotypes that were different enough to represent separate Leucoagaricus species. The Sericomyrmex species and one of the Trachymyrmex species reared the same fungal cultivar in all sampled colonies, but the remaining four Trachymyrmex species largely shared the other cultivars. Fungal enzyme activity spectra were significantly affected by both cultivar species and farming ant species, and more so for certain ant-cultivar combinations than others. However, relative changes in activity of single enzymes only depended on cultivar genotype and not on the ant species farming a cultivar. CONCLUSIONS Ant cultivar symbiont-specificity varied from almost full symbiont sharing to one-to-one specialization, suggesting that trade-offs between enzyme activity spectra and life-history traits such as desiccation tolerance, disease susceptibility and temperature sensitivity may apply in some combinations but not in others. We hypothesize that this may be related to ecological specialization in general, but this awaits further testing. Our finding of both cryptic ant species and extensive cultivar diversity underlines the importance of identifying all species-level variation before embarking on estimates of interaction specificity.
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Affiliation(s)
- Henrik H De Fine Licht
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100, Copenhagen, Denmark.
- Present address: Section for Organismal Biology, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg, Denmark.
| | - Jacobus J Boomsma
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100, Copenhagen, Denmark.
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20
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Masiulionis VE, Rabeling C, De Fine Licht HH, Schultz T, Bacci M, Bezerra CMS, Pagnocca FC. A Brazilian population of the asexual fungus-growing ant Mycocepurus smithii (Formicidae, Myrmicinae, Attini) cultivates fungal symbionts with gongylidia-like structures. PLoS One 2014; 9:e103800. [PMID: 25101899 PMCID: PMC4125159 DOI: 10.1371/journal.pone.0103800] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 07/07/2014] [Indexed: 01/23/2023] Open
Abstract
Attine ants cultivate fungi as their most important food source and in turn the fungus is nourished, protected against harmful microorganisms, and dispersed by the ants. This symbiosis evolved approximately 50-60 million years ago in the late Paleocene or early Eocene, and since its origin attine ants have acquired a variety of fungal mutualists in the Leucocoprineae and the distantly related Pterulaceae. The most specialized symbiotic interaction is referred to as "higher agriculture" and includes leafcutter ant agriculture in which the ants cultivate the single species Leucoagaricus gongylophorus. Higher agriculture fungal cultivars are characterized by specialized hyphal tip swellings, so-called gongylidia, which are considered a unique, derived morphological adaptation of higher attine fungi thought to be absent in lower attine fungi. Rare reports of gongylidia-like structures in fungus gardens of lower attines exist, but it was never tested whether these represent rare switches of lower attines to L. gonglyphorus cultivars or whether lower attine cultivars occasionally produce gongylidia. Here we describe the occurrence of gongylidia-like structures in fungus gardens of the asexual lower attine ant Mycocepurus smithii. To test whether M. smithii cultivates leafcutter ant fungi or whether lower attine cultivars produce gongylidia, we identified the M. smithii fungus utilizing molecular and morphological methods. Results shows that the gongylidia-like structures of M. smithii gardens are morphologically similar to gongylidia of higher attine fungus gardens and can only be distinguished by their slightly smaller size. A molecular phylogenetic analysis of the fungal ITS sequence indicates that the gongylidia-bearing M. smithii cultivar belongs to the so-called "Clade 1"of lower Attini cultivars. Given that M. smithii is capable of cultivating a morphologically and genetically diverse array of fungal symbionts, we discuss whether asexuality of the ant host maybe correlated with low partner fidelity and active symbiont choice between fungus and ant mutualists.
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Affiliation(s)
| | - Christian Rabeling
- Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, United States of America
- Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, D.C., United States of America
| | - Henrik H. De Fine Licht
- Section for Organismal Biology, Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ted Schultz
- Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, D.C., United States of America
| | - Maurício Bacci
- Instituto de Biociências, São Paulo State University, Rio Claro, SP, Brazil
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21
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Seal JN, Schiøtt M, Mueller UG. Ant-fungus species combinations engineer physiological activity of fungus gardens. ACTA ACUST UNITED AC 2014; 217:2540-7. [PMID: 24803469 DOI: 10.1242/jeb.098483] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Fungus-gardening insects are among the most complex organisms because of their extensive co-evolutionary histories with obligate fungal symbionts and other microbes. Some fungus-gardening insect lineages share fungal symbionts with other members of their lineage and thus exhibit diffuse co-evolutionary relationships, while others exhibit little or no symbiont sharing, resulting in host-fungus fidelity. The mechanisms that maintain this symbiont fidelity are currently unknown. Prior work suggested that derived leaf-cutting ants in the genus Atta interact synergistically with leaf-cutter fungi (Attamyces) by exhibiting higher fungal growth rates and enzymatic activities than when growing a fungus from the sister-clade to Attamyces (so-called 'Trachymyces'), grown primarily by the non-leaf cutting Trachymyrmex ants that form, correspondingly, the sister-clade to leaf-cutting ants. To elucidate the enzymatic bases of host-fungus specialization in leaf-cutting ants, we conducted a reciprocal fungus-switch experiment between the ant Atta texana and the ant Trachymyrmex arizonensis and report measured enzymatic activities of switched and sham-switched fungus gardens to digest starch, pectin, xylan, cellulose and casein. Gardens exhibited higher amylase and pectinase activities when A. texana ants cultivated Attamyces compared with Trachymyces fungi, consistent with enzymatic specialization. In contrast, gardens showed comparable amylase and pectinase activities when T. arizonensis cultivated either fungal species. Although gardens of leaf-cutting ants are not known to be significant metabolizers of cellulose, T. arizonensis were able to maintain gardens with significant cellulase activity when growing either fungal species. In contrast to carbohydrate metabolism, protease activity was significantly higher in Attamyces than in Trachymyces, regardless of the ant host. Activity of some enzymes employed by this symbiosis therefore arises from complex interactions between the ant host and the fungal symbiont.
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Affiliation(s)
- J N Seal
- Department of Biology, University of Texas at Tyler, 3900 University Blvd, Tyler, TX 75799, USA Integrative Biology, University of Texas at Austin, 1 University Station C0930, Austin, TX 78712, USA
| | - M Schiøtt
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark
| | - U G Mueller
- Integrative Biology, University of Texas at Austin, 1 University Station C0930, Austin, TX 78712, USA
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