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Metzler S, Kirchner J, Grasse AV, Cremer S. Trade-offs between immunity and competitive ability in fighting ant males. BMC Ecol Evol 2023; 23:37. [PMID: 37550612 PMCID: PMC10405452 DOI: 10.1186/s12862-023-02137-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 06/16/2023] [Indexed: 08/09/2023] Open
Abstract
BACKGROUND Fighting disease while fighting rivals exposes males to constraints and trade-offs during male-male competition. We here tested how both the stage and intensity of infection with the fungal pathogen Metarhizium robertsii interfere with fighting success in Cardiocondyla obscurior ant males. Males of this species have evolved long lifespans during which they can gain many matings with the young queens of the colony, if successful in male-male competition. Since male fights occur inside the colony, the outcome of male-male competition can further be biased by interference of the colony's worker force. RESULTS We found that severe, but not yet mild, infection strongly impaired male fighting success. In late-stage infection, this could be attributed to worker aggression directed towards the infected rather than the healthy male and an already very high male morbidity even in the absence of fighting. Shortly after pathogen exposure, however, male mortality was particularly increased during combat. Since these males mounted a strong immune response, their reduced fighting success suggests a trade-off between immune investment and competitive ability already early in the infection. Even if the males themselves showed no difference in the number of attacks they raised against their healthy rivals across infection stages and levels, severely infected males were thus losing in male-male competition from an early stage of infection on. CONCLUSIONS Males of the ant C. obscurior have a well-developed immune system that raises a strong immune response very fast after fungal exposure. This allows them to cope with mild pathogen exposures without compromising their success in male-male competition, and hence to gain multiple mating opportunities with the emerging virgin queens of the colony. Under severe infection, however, they are weak fighters and rarely survive a combat already at early infection when raising an immune response, as well as at progressed infection, when they are morbid and preferentially targeted by worker aggression. Workers thereby remove males that pose a future disease threat by biasing male-male competition. Our study thus reveals a novel social immunity mechanism how social insect workers protect the colony against disease risk.
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Affiliation(s)
- Sina Metzler
- ISTA (Institute of Science and Technology Austria), Am Campus 1, Klosterneuburg, 3400, Austria
| | - Jessica Kirchner
- ISTA (Institute of Science and Technology Austria), Am Campus 1, Klosterneuburg, 3400, Austria
| | - Anna V Grasse
- ISTA (Institute of Science and Technology Austria), Am Campus 1, Klosterneuburg, 3400, Austria
| | - Sylvia Cremer
- ISTA (Institute of Science and Technology Austria), Am Campus 1, Klosterneuburg, 3400, Austria.
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Vidal M, Königseder F, Giehr J, Schrempf A, Lucas C, Heinze J. Worker ants promote outbreeding by transporting young queens to alien nests. Commun Biol 2021; 4:515. [PMID: 33941829 PMCID: PMC8093424 DOI: 10.1038/s42003-021-02016-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 03/22/2021] [Indexed: 11/09/2022] Open
Abstract
Choosing the right mating partner is one of the most critical decisions in the life of a sexually reproducing organism and is the basis of sexual selection. This choice is usually assumed to be made by one or both of the sexual partners. Here, we describe a system in which a third party – the siblings – promote outbreeding by their sisters: workers of the tiny ant Cardiocondyla elegans carry female sexuals from their natal nest over several meters and drop them in the nest of another, unrelated colony to promote outbreeding with wingless, stationary males. Workers appear to choose particular recipient colonies into which they transfer numerous female sexuals. Assisted outbreeding and indirect female choice in the ant C. elegans are comparable to human matchmaking and suggest a hitherto unknown aspect of natural history – third party sexual selection. Our study highlights that research at the intersection between social evolution and reproductive biology might reveal surprising facets of animal behavior. Vidal et al. identify a breeding system in the ant Cardiocondyla elegans that avoids colonial inbreeding, managed by a third party of worker ants. This system bears similarities to human matchmaking, but with fundamental genetic drivers rather than social ones.
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Affiliation(s)
- Mathilde Vidal
- Chair of Zoology and Evolutionary Biology - University of Regensburg, Regensburg, Germany.
| | - Florian Königseder
- Chair of Zoology and Evolutionary Biology - University of Regensburg, Regensburg, Germany
| | - Julia Giehr
- Chair of Zoology and Evolutionary Biology - University of Regensburg, Regensburg, Germany
| | - Alexandra Schrempf
- Chair of Zoology and Evolutionary Biology - University of Regensburg, Regensburg, Germany
| | - Christophe Lucas
- Institut de Recherche sur la Biologie de l'Insecte (UMR7261), CNRS - Université de Tours, Tours, France
| | - Jürgen Heinze
- Chair of Zoology and Evolutionary Biology - University of Regensburg, Regensburg, Germany
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Heinze J, Frohschammer S, Bernadou A. When invasive ants meet: effects of outbreeding on queen performance in the tramp ant Cardiocondyla itsukii. INSECT SCIENCE 2019; 26:333-340. [PMID: 28834236 DOI: 10.1111/1744-7917.12530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 07/25/2017] [Accepted: 08/09/2017] [Indexed: 06/07/2023]
Abstract
Most disturbed habitats in the tropics and subtropics harbor numerous species of invasive ants, and occasionally the same species has been introduced repeatedly from multiple geographical sources. We examined how experimental crossbreeding between sexuals from different populations affects the fitness of queens of the tramp ant Cardiocondyla itsukii, which is widely distributed in Asia and the Pacific Islands. Eggs laid by queens that mated with nestmate males had a higher hatching rate than eggs laid by queens mated to males from neighboring (Hawaii × Kauai) or distant introduced populations (Hawaii/Kauai × Okinawa). Furthermore, inbreeding queens had a longer lifespan and produced a less female-biased offspring sex ratio than queens from allopatric mating. This suggests that the genetic divergence between different source populations may already be so large that in case of multiple invasions eventual crossbreeding might negatively affect the fitness of tramp ants.
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Affiliation(s)
- Jürgen Heinze
- LS Zoologie/Evolutionsbiologie, Universität Regensburg, Regensburg, Germany
| | | | - Abel Bernadou
- LS Zoologie/Evolutionsbiologie, Universität Regensburg, Regensburg, Germany
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Abril S, Diaz M, Lenoir A, Ivon Paris C, Boulay R, Gómez C. Cuticular hydrocarbons correlate with queen reproductive status in native and invasive Argentine ants (Linepithema humile, Mayr). PLoS One 2018; 13:e0193115. [PMID: 29470506 PMCID: PMC5823440 DOI: 10.1371/journal.pone.0193115] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 02/05/2018] [Indexed: 11/18/2022] Open
Abstract
In insect societies, chemical communication plays an important role in colony reproduction and individual social status. Many studies have indicated that cuticular hydrocarbons (CHCs) are the main chemical compounds encoding reproductive status. However, these studies have largely focused on queenless or monogynous species whose workers are capable of egg laying and have mainly explored the mechanisms underlying queen-worker or worker-worker reproductive conflicts. Less is known about what occurs in highly polygynous ant species with permanently sterile workers. Here, we used the Argentine ant as a model to examine the role of CHCs in communicating reproductive information in such insect societies. The Argentine ant is unicolonial, highly polygynous, and polydomous. We identified several CHCs whose presence and levels were correlated with queen age, reproductive status, and fertility. Our results also provide new insights into queen executions in the Argentine ant, a distinctive feature displayed by this species in its introduced range. Each spring, just before new sexuals appear, workers eliminate up to 90% of the mated queens in their colonies. We discovered that queens that survived execution had different CHC profiles from queens present before and during execution. More specifically, levels of some CHCs were higher in the survivors, suggesting that workers could eliminate queens based on their chemical profiles. In addition, queen CHC profiles differed based on season and species range (native vs. introduced). Overall, the results of this study provide new evidence that CHCs serve as queen signals and do more than just regulate worker reproduction.
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Affiliation(s)
- Sílvia Abril
- Departament de Ciències Ambientals, Universitat de Girona, Girona, Spain
- * E-mail:
| | - Mireia Diaz
- Departament de Ciències Ambientals, Universitat de Girona, Girona, Spain
| | - Alain Lenoir
- Institut de Recherche sur la Biologie de l’Insecte, Université François Rabelais de Tours, Tours, France
| | - Carolina Ivon Paris
- Departamento Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Raphaël Boulay
- Institut de Recherche sur la Biologie de l’Insecte, Université François Rabelais de Tours, Tours, France
| | - Crisanto Gómez
- Departament de Ciències Ambientals, Universitat de Girona, Girona, Spain
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Mothapo NP, Wossler TC. “You are not always what you eat”: diet did not override intrinsic nestmate recognition cues in Argentine ants from two supercolonies in South Africa. AFRICAN ZOOLOGY 2016. [DOI: 10.1080/15627020.2016.1236670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Natasha P Mothapo
- DST-NRF Centre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa
| | - Theresa C Wossler
- DST-NRF Centre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa
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Inoue MN, Ito F, Goka K. Queen execution increases relatedness among workers of the invasive Argentine ant, Linepithema humile. Ecol Evol 2015; 5:4098-107. [PMID: 26445661 PMCID: PMC4588641 DOI: 10.1002/ece3.1681] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 07/30/2015] [Indexed: 11/29/2022] Open
Abstract
Polygyny in social insects can greatly reduce within‐nest genetic relatedness. In polygynous ant species, potential rival queens in colonies with multiple queens are often executed by other queens, workers, or both. The Argentine ant, Linepithema humile, native to South America, forms a “supercolony” that is composed of a large number of nests and is considered to contribute to the ant's invasion success. Currently, four mutually antagonistic supercolonies are contiguously distributed within a small area of Japan. Here, we analyzed the genetic structure and relatedness within and among the four supercolonies using microsatellite markers to clarify how L. humile maintains its supercoloniality. The results of AMOVA and BASP, the FST values, and the existence of several private alleles indicated that the L. humile population in the Kobe area had a characteristic genetic structure. Within a given supercolony, there was significant genetic differentiation (FST) among workers collected in May and those collected in September. The significant deviation from Hardy–Weinberg equilibrium increased, and the relatedness among workers significantly increased from May to September in all supercolonies. This result suggested that the supercolonies replaced old queens with new ones during the reproductive season, thus supporting the plausibility of queen execution. From the perspective of kin selection, workers collectively eliminate queens, thereby increasing their own inclusive fitness. Restricted gene flow among supercolonies, together with mating with sib and queen execution, could help to maintain the unique social structure of L. humile, the distribution of which is expanding worldwide.
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Affiliation(s)
- Maki N Inoue
- Department of Applied Biological Science Tokyo University of Agriculture and Technology 3-5-8 Saiwaicho Fuchu Tokyo 183-8509 Japan
| | - Fuminori Ito
- Faculty of Agriculture Kagawa University 2393 Ikenobe Miki Kagawa 761-0795 Japan
| | - Koichi Goka
- National Institute for Environmental Studies 16-2 Onogawa Tsukuba Ibaraki 305-0053 Japan
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Helft F, Monnin T, Doums C. First Evidence of Inclusive Sexual Selection in the Ant Cataglyphis cursor: Worker Aggressions Differentially Affect Male Access to Virgin Queens. Ethology 2015. [DOI: 10.1111/eth.12376] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Florence Helft
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7618 Institute of Ecology and Environmental Sciences of Paris; Paris France
- École Pratique des Hautes Études; Paris France
- Département Systématique et Évolution; ISYEB, UMR 7205 CNRS UPMC Muséum National d'Histoire Naturelle; Paris France
| | - Thibaud Monnin
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7618 Institute of Ecology and Environmental Sciences of Paris; Paris France
| | - Claudie Doums
- École Pratique des Hautes Études; Paris France
- Département Systématique et Évolution; ISYEB, UMR 7205 CNRS UPMC Muséum National d'Histoire Naturelle; Paris France
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BLIGHT O, BERVILLE L, VOGEL V, HEFETZ A, RENUCCI M, ORGEAS J, PROVOST E, KELLER L. Variation in the level of aggression, chemical and genetic distance among three supercolonies of the Argentine ant in Europe. Mol Ecol 2012; 21:4106-21. [DOI: 10.1111/j.1365-294x.2012.05668.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Lester PJ, Gruber MAM. Comment on Moffett: "Supercolonies of billions in an invasive ant: What is a society?". Behav Ecol 2012. [DOI: 10.1093/beheco/ars048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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