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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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Eyer PA, Finand B, Mona S, Khimoun A, D'ettorre P, Fédérici P, Leroy C, Cornette R, Chifflet-Belle P, Monnin T, Doums C. Integrative characterization of genetic and phenotypic differentiation in an ant species complex with strong hierarchical population structure and low dispersal abilities. Heredity (Edinb) 2023; 130:163-176. [PMID: 36585503 PMCID: PMC9981590 DOI: 10.1038/s41437-022-00590-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 12/21/2022] [Accepted: 12/21/2022] [Indexed: 12/31/2022] Open
Abstract
Low dispersal, occurrence of asexual reproduction and geographic discontinuity increase genetic differentiation between populations, which ultimately can lead to speciation. In this work, we used a multidisciplinary framework to characterize the genetic and phenotypic differentiation between and within two cryptic ant species with restricted dispersal, Cataglyphis cursor and C. piliscapa and used behavioral experiments to test for reproductive isolation. Their distribution is segregated by the Rhône River and they have been traditionally distinguished only by hair numbers, although a statistical assessment is still lacking. We found strong genetic (microsatellites, nuclear and mitochondrial sequences), morphological (number of hairs, tibia length, male genitalia) and chemical (cuticular hydrocarbons) differentiation not only between species but also among localities within species. However, inter-specific differentiation was slightly higher than intra-specific differentiation for most markers. Overall, this pattern could either reflect reproductive isolation or could result from a longer period of geographic isolation between species than among localities within species without necessarily involving reproductive isolation. Interestingly, our behavioral experiments showed an absence of mating between species associated to a higher aggressiveness of workers towards heterospecific males. This suggests that sexual selection may, at least partially, fuel reproductive isolation. We also showed that cuticular hydrocarbons, mtDNA sequences and number of hairs provide reliable criteria allowing species discrimination. Overall, this species complex offers a case study to further investigate varying stages of a speciation continuum by estimating reproductive isolation between pairs of localities varying by their level of genetic differentiation.
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Affiliation(s)
- P A Eyer
- Department of Entomology, 2143 TAMU, Texas A&M University, College Station, TX, 77843-2143, USA.
- Institut de Systématique, Évolution, Biodiversité (ISYEB), UMR 7205, MNHN, CNRS, EPHE-PSL, Sorbonne Université, Université des Antilles, 75005, Paris, France.
- EPHE, PSL University, 75005, Paris, France.
| | - B Finand
- Institut de Systématique, Évolution, Biodiversité (ISYEB), UMR 7205, MNHN, CNRS, EPHE-PSL, Sorbonne Université, Université des Antilles, 75005, Paris, France
| | - S Mona
- Institut de Systématique, Évolution, Biodiversité (ISYEB), UMR 7205, MNHN, CNRS, EPHE-PSL, Sorbonne Université, Université des Antilles, 75005, Paris, France
- EPHE, PSL University, 75005, Paris, France
| | - A Khimoun
- Institut de Systématique, Évolution, Biodiversité (ISYEB), UMR 7205, MNHN, CNRS, EPHE-PSL, Sorbonne Université, Université des Antilles, 75005, Paris, France
- EPHE, PSL University, 75005, Paris, France
- Biogéosciences, UMR 6282 CNRS, Université Bourgogne Franche-Comté, 6 Boulevard Gabriel, 21000, Dijon, France
| | - P D'ettorre
- Laboratory of Experimental and Comparative Ethology, University of Paris 13, Sorbonne Paris Cité, 93430, Villetaneuse, France
| | - P Fédérici
- Sorbonne Université, Université Paris Est Créteil, CNRS, INRAe, IRD, Institute of Ecology and Environmental sciences of Paris, iEES-Paris, 75005, Paris, France
| | - C Leroy
- Biogéosciences, UMR 6282 CNRS, Université Bourgogne Franche-Comté, 6 Boulevard Gabriel, 21000, Dijon, France
| | - R Cornette
- Institut de Systématique, Évolution, Biodiversité (ISYEB), UMR 7205, MNHN, CNRS, EPHE-PSL, Sorbonne Université, Université des Antilles, 75005, Paris, France
| | - P Chifflet-Belle
- Institut de Systématique, Évolution, Biodiversité (ISYEB), UMR 7205, MNHN, CNRS, EPHE-PSL, Sorbonne Université, Université des Antilles, 75005, Paris, France
- EPHE, PSL University, 75005, Paris, France
| | - T Monnin
- Sorbonne Université, Université Paris Est Créteil, CNRS, INRAe, IRD, Institute of Ecology and Environmental sciences of Paris, iEES-Paris, 75005, Paris, France
| | - C Doums
- Institut de Systématique, Évolution, Biodiversité (ISYEB), UMR 7205, MNHN, CNRS, EPHE-PSL, Sorbonne Université, Université des Antilles, 75005, Paris, France
- EPHE, PSL University, 75005, Paris, France
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Boulay R, Aron S, Cerdá X, Doums C, Graham P, Hefetz A, Monnin T. Social Life in Arid Environments: The Case Study of Cataglyphis Ants. ANNUAL REVIEW OF ENTOMOLOGY 2017; 62:305-321. [PMID: 27860520 DOI: 10.1146/annurev-ento-031616-034941] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Unlike most desert-dwelling animals, Cataglyphis ants do not attempt to escape the heat; rather, they apply their impressive heat tolerance to avoid competitors and predators. This thermally defined niche has promoted a range of adaptations both at the individual and colony levels. We have also recently discovered that within the genus Cataglyphis there are incredibly diverse social systems, modes of reproduction, and dispersal, prompting the tantalizing question of whether social diversity may also be a consequence of the harsh environment within which we find these charismatic ants. Here we review recent advances regarding the physiological, behavioral, life-history, colony, and ecological characteristics of Cataglyphis and consider perspectives on future research that will build our understanding of organic adaptive responses to desertification.
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Affiliation(s)
- Raphaël Boulay
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- Institute of Insect Biology, Tours University, 37200 Tours, France
| | - Serge Aron
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- Evolutionary Biology and Ecology, Université Libre de Bruxelles, 1050, Belgium
| | - Xim Cerdá
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- Doñana Biological Station, CSIC, 41092 Seville, Spain
| | - Claudie Doums
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- Institute of Systematics, Evolution, and Biodiversity, CNRS, UPMC, EPHE, MNHN, 75005 Paris, France
| | - Paul Graham
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- School of Life Sciences, University of Sussex, Brighton, BN1 9QG, United Kingdom
| | - Abraham Hefetz
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Thibaud Monnin
- Le Studium Loire Valley Institute for Advanced Studies, 45000 Orléans, France;
- UMR 7618, Institute of Ecology and Environmental Sciences of Paris, Sorbonne Universités, UPMC Univ Paris 06, 75252 Paris, France
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