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Blacher P, Zahnd S, Purcell J, Avril A, Honorato TO, Bailat‐Rosset G, Staedler D, Brelsford A, Chapuisat M. Species recognition limits mating between hybridizing ant species. Evolution 2022; 76:2105-2115. [PMID: 35802833 PMCID: PMC9541793 DOI: 10.1111/evo.14566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 06/21/2022] [Accepted: 06/29/2022] [Indexed: 01/22/2023]
Abstract
Identifying mechanisms limiting hybridization is a central goal of speciation research. Here, we studied premating and postmating barriers to hybridization between two ant species, Formica selysi and Formica cinerea. These species hybridize in the Rhône valley in Switzerland, where they form a mosaic hybrid zone, with limited introgression from F. selysi into F. cinerea. There was no sign of temporal isolation between the two species in the production of queens and males. With choice experiments, we showed that queens and males strongly prefer to mate with conspecifics. Yet, we did not detect postmating barriers caused by genetic incompatibilities. Specifically, hybrids of all sexes and castes were found in the field and F1 hybrid workers did not show reduced viability compared to nonhybrid workers. To gain insights into the cues involved in species recognition, we analyzed the cuticular hydrocarbons (CHCs) of queens, males, and workers and staged dyadic encounters between workers. CHC profiles differed markedly between species, but were similar in F. cinerea and hybrids. Accordingly, workers also discriminated species, but they did not discriminate F. cinerea and hybrids. We discuss how the CHC-based recognition system of ants may facilitate the establishment of premating barriers to hybridization, independent of hybridization costs.
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Affiliation(s)
- Pierre Blacher
- Departement of Ecology and EvolutionUniversity of LausanneLausanneCH‐1015Switzerland
| | - Sacha Zahnd
- Departement of Ecology and EvolutionUniversity of LausanneLausanneCH‐1015Switzerland
| | - Jessica Purcell
- Department of EntomologyUniversity of CaliforniaRiversideCalifornia92521USA
| | - Amaury Avril
- Departement of Ecology and EvolutionUniversity of LausanneLausanneCH‐1015Switzerland
| | | | | | - Davide Staedler
- Scitec Research SALausanneCH‐1007Switzerland,Department of Biomedical SciencesUniversity of LausanneLausanneCH‐1011Switzerland
| | - Alan Brelsford
- Department of BiologyUniversity of CaliforniaRiversideCalifornia92521USA
| | - Michel Chapuisat
- Departement of Ecology and EvolutionUniversity of LausanneLausanneCH‐1015Switzerland
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2
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Portinha B, Avril A, Bernasconi C, Helanterä H, Monaghan J, Seifert B, Sousa VC, Kulmuni J, Nouhaud P. Whole-genome analysis of multiple wood ant population pairs supports similar speciation histories, but different degrees of gene flow, across their European ranges. Mol Ecol 2022; 31:3416-3431. [PMID: 35460311 PMCID: PMC9320829 DOI: 10.1111/mec.16481] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 04/07/2022] [Accepted: 04/11/2022] [Indexed: 11/30/2022]
Abstract
The application of demographic history modelling and inference to the study of divergence between species has become a cornerstone of speciation genomics. Speciation histories are usually reconstructed by analysing single populations from each species, assuming that the inferred population history represents the actual speciation history. However, this assumption may not be met when species diverge with gene flow, for example, when secondary contact may be confined to specific geographic regions. Here, we tested whether divergence histories inferred from heterospecific populations may vary depending on their geographic locations, using the two wood ant species Formica polyctena and F. aquilonia. We performed whole-genome resequencing of 20 individuals sampled in multiple locations across the European ranges of both species. Then, we reconstructed the histories of distinct heterospecific population pairs using a coalescent-based approach. Our analyses always supported a scenario of divergence with gene flow, suggesting that divergence started in the Pleistocene (c. 500 kya) and occurred with continuous asymmetrical gene flow from F. aquilonia to F. polyctena until a recent time, when migration became negligible (2-19 kya). However, we found support for contemporary gene flow in a sympatric pair from Finland, where the species hybridise, but no signature of recent bidirectional gene flow elsewhere. Overall, our results suggest that divergence histories reconstructed from a few individuals may be applicable at the species level. Nonetheless, the geographical context of populations chosen to represent their species should be taken into account, as it may affect estimates of migration rates between species when gene flow is spatially heterogeneous.
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Affiliation(s)
- Beatriz Portinha
- Organismal & Evolutionary Biology Research ProgrammeUniversity of HelsinkiHelsinkiFinland
- cE3cCentre for Ecology, Evolution and Environmental changesFaculdade de CiênciasUniversidade de LisboaLisboaPortugal
| | - Amaury Avril
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
| | | | | | | | | | - Vitor C. Sousa
- cE3cCentre for Ecology, Evolution and Environmental changesFaculdade de CiênciasUniversidade de LisboaLisboaPortugal
| | - Jonna Kulmuni
- Organismal & Evolutionary Biology Research ProgrammeUniversity of HelsinkiHelsinkiFinland
- Tvärminne Zoological StationUniversity of HelsinkiHankoFinland
| | - Pierre Nouhaud
- Organismal & Evolutionary Biology Research ProgrammeUniversity of HelsinkiHelsinkiFinland
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3
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Cordonnier M, Kaufmann B, Simon L, Escarguel G, Mondy N. Discrimination of conspecifics from heterospecifics in a hybrid zone: Behavioral and chemical cues in ants. INSECT SCIENCE 2022; 29:276-288. [PMID: 33913250 DOI: 10.1111/1744-7917.12915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 02/17/2021] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
Species and nestmate recognition in social insects occurs mostly through cuticular hydrocarbons acting as chemical cues. These compounds generate a colony-specific odor profile depending on genetic and environmental factors. Species and nestmate recognition results in specific behavioral responses, regulating the level of aggression toward other individuals during an interaction. Although species discrimination and recognition cues have been poorly studied in the context of interspecific hybridization, such systems offer an opportunity to further investigate the influence of heritable and environmental factors on recognition. We explored the strength of discrimination in a hybrid zone between two ant species-Tetramorium immigrans and T. caespitum-by comparing cuticular hydrocarbon profiles and measuring intra- and interspecific worker aggression in both areas of sympatry and areas of allopatry among species. Species cuticular hydrocarbon profiles were well-differentiated and interspecific aggression was high, revealing highly discriminating species recognition cues. Hybrids' cuticular hydrocarbon profiles consisted of a mixture of the parental bouquets, but also exhibited hybrid-specific patterns. Behavioral assays showed that T. immigrans is as aggressive toward hybrids as toward heterospecifics. Finally, aggression between heterospecific workers was lower when interacting individuals came from areas of sympatry among species than from areas of allopatry. Taken as a whole, these findings paint a particularly complex picture of the recognition system in T. immigrans, T. caespitum, and their hybrids, and highlight that hybrid zones afford a still underexplored opportunity for investigating recognition mechanisms and discrimination between species.
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Affiliation(s)
- Marion Cordonnier
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
| | - Bernard Kaufmann
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
| | - Laurent Simon
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
| | - Gilles Escarguel
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
| | - Nathalie Mondy
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France
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4
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Siddiqui JA, Bamisile BS, Khan MM, Islam W, Hafeez M, Bodlah I, Xu Y. Impact of invasive ant species on native fauna across similar habitats under global environmental changes. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:54362-54382. [PMID: 34405331 DOI: 10.1007/s11356-021-15961-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 08/09/2021] [Indexed: 06/13/2023]
Abstract
Biotic invasions can predominantly alter the dynamics, composition, functions, and structure of natural ecosystems. Social insects, particularly ants, are among the most damaging invasive alien species. Invasive ant species are among the supreme threats to ecosystems. There are about 23 species of invasive ants recorded worldwide, according to the ant invasive databases. The ecological impacts of invasive ants comprise predation, hybridization, and competition with native species that changes the ecosystem processes with the biodiversity loss and upsurge of pests. The effects of invasion on native fauna in the same habitats might be catastrophic for the native community through various ecological mechanisms, e.g., habitat disturbance, resource competition, limiting the foraging activity of native species, and various other indirect mechanisms of invasive species. Invasive species may have harmful impacts on habitats and devastating effects on natural flora and fauna, and stopping these new species from being introduced is the most effective way to deter future invasions and maintain biodiversity. This paper reviews the literature to evaluate the effects of invasive ant species on the native species, including vertebrates, invertebrates, and plants sharing the same habitats as the non-native species under global environmental changes. We also highlighted the various management strategies that could be adopted in minimizing the adverse effects of these invasive ant species on the natural ecosystem. To this end, strategies that could regulate the mode and rate of invasion by these alien ant species are the most effective ways to deter future invasions and maintain biodiversity.
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Affiliation(s)
- Junaid Ali Siddiqui
- Red Imported Fire Ant Research Centre, South China Agricultural University, Guangzhou, 510642, Guangdong, China
| | - Bamisope Steve Bamisile
- Red Imported Fire Ant Research Centre, South China Agricultural University, Guangzhou, 510642, Guangdong, China.
| | - Muhammad Musa Khan
- Key Laboratory of Bio-Pesticide Innovation and Application, Engineering Research Centre of Biological Control, South China Agricultural University, Guangzhou, China
| | - Waqar Islam
- College of Geography, Fujian Normal University, Fuzhou, 350007, China
| | - Muhammad Hafeez
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Imran Bodlah
- Insect Biodiversity and Conservation Group, Department of Entomology, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan
| | - Yijuan Xu
- Red Imported Fire Ant Research Centre, South China Agricultural University, Guangzhou, 510642, Guangdong, China.
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5
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Cordonnier M, Escarguel G, Dumet A, Kaufmann B. Multiple mating in the context of interspecific hybridization between two Tetramorium ant species. Heredity (Edinb) 2020; 124:675-684. [PMID: 32205865 DOI: 10.1038/s41437-020-0310-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 02/29/2020] [Accepted: 03/11/2020] [Indexed: 12/24/2022] Open
Abstract
In eusocial Hymenoptera, haplodiploidy and polyandry may facilitate selection for hybridization. Interspecific hybridization is widespread in ants and can lead to hybrid inviability as well as the formation of new species through hybrid speciation. However, in ants, polyandry is uncommon. By analyzing microsatellite markers on 15 ant workers per colony, we show that the mating system of 28 pure colonies of Tetramorium immigrans, 15 pure colonies of Tetramorium caespitum, and 27 hybrid colonies is a monogyne/polyandrous mating system, with a higher mating rate in T. caespitum (mean = 2.4 males vs. 1.7 in T. immigrans). Hybrid queens, but no hybrid fathers, were deduced from workers' genotypes, in accordance with Haldane's rule extended to haplodiploid organisms, which states that the haploid sex should more often be sterile or inviable. In five colonies, hybridization and multiple mating allowed the simultaneous production of both hybrid and nonhybrid offspring. Although rare, these situations hinted at asymmetrical, larger contributions of T. immigrans vs. T. caespitum males to offspring production. Together, these findings point toward a complex and dynamic mating system in T. immigrans and T. caespitum, and contribute to better understand interspecific hybridization mechanisms and their consequences on genetic and taxonomic diversity. The study of polyandry within a hybrid zone is unprecedented and opens new opportunities to better understand interspecific hybridization mechanisms and their short- to long-term consequences.
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Affiliation(s)
- Marion Cordonnier
- Univ. Lyon, UMR5023 Ecologie des Hydrosystèmes Naturels et Anthropisés, ENTPE, CNRS, Université Lyon 1, Villeurbanne, F-69622, Lyon, France.
| | - Gilles Escarguel
- Univ. Lyon, UMR5023 Ecologie des Hydrosystèmes Naturels et Anthropisés, ENTPE, CNRS, Université Lyon 1, Villeurbanne, F-69622, Lyon, France
| | - Adeline Dumet
- Univ. Lyon, UMR5023 Ecologie des Hydrosystèmes Naturels et Anthropisés, ENTPE, CNRS, Université Lyon 1, Villeurbanne, F-69622, Lyon, France
| | - Bernard Kaufmann
- Univ. Lyon, UMR5023 Ecologie des Hydrosystèmes Naturels et Anthropisés, ENTPE, CNRS, Université Lyon 1, Villeurbanne, F-69622, Lyon, France
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6
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Cordonnier M, Gayet T, Escarguel G, Kaufmann B. From hybridization to introgression between two closely related sympatric ant species. J ZOOL SYST EVOL RES 2019. [DOI: 10.1111/jzs.12297] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Marion Cordonnier
- UMR5023 Ecologie des Hydrosystèmes Naturels et Anthropisés, CNRS, Université Lyon 1, ENTPE Université Lyon Lyon France
| | - Thibault Gayet
- UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, CNRS, Université Lyon 1 Université de Lyon Lyon France
- Unité Cervidés Sangliers Office National de la Chasse et de la Faune Sauvage Birieux France
| | - Gilles Escarguel
- UMR5023 Ecologie des Hydrosystèmes Naturels et Anthropisés, CNRS, Université Lyon 1, ENTPE Université Lyon Lyon France
| | - Bernard Kaufmann
- UMR5023 Ecologie des Hydrosystèmes Naturels et Anthropisés, CNRS, Université Lyon 1, ENTPE Université Lyon Lyon France
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7
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Krapf P, Hochenegger N, Arthofer W, Schlick-Steiner BC, Steiner FM. Comparing ant behaviour indices for fine-scale analyses. Sci Rep 2019; 9:6856. [PMID: 31048736 PMCID: PMC6497665 DOI: 10.1038/s41598-019-43313-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 04/17/2019] [Indexed: 12/24/2022] Open
Abstract
Animal behaviour often is characterised by standardised assays. In social insects such as ants, behaviour assays are for example used to characterise aggressive and peaceful behaviour. Such assays differ in the number of individuals, the duration and place of assays, and the scoring scales. Also the behaviour indices used to summarise the results differ. Here, we compared five behaviour indices (Aggression Index, Mean Maximum Aggression Index; and the newly introduced Mean Maximum Peace Index, Mean Behaviour Index aggressive, and Mean Behaviour Index peaceful) using a scoring scale that comprises peaceful and aggressive behaviour. The indices were applied on eight simulations and three observed data sets. The five indices were correlated but frequently differed in their means. Multiple indices were needed to capture the complete behaviour range. Furthermore, subtle differences in workers' behaviour, that is, differences that go beyond the presence/absence of aggression, were only identified when considering multiple indices. We infer that the indices applied are differently suited for different analyses. Fine-scale analyses of behavioural variation profit from using more than one index. The particular choice of index or indices likely influences the interpretation of behaviour and should be carefully done in the light of study species and research question.
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Affiliation(s)
- Patrick Krapf
- Molecular Ecology Group, Department of Ecology, University of Innsbruck, Technikerstr. 25, Innsbruck, 6020, Austria.
| | - Nadine Hochenegger
- Molecular Ecology Group, Department of Ecology, University of Innsbruck, Technikerstr. 25, Innsbruck, 6020, Austria
| | - Wolfgang Arthofer
- Molecular Ecology Group, Department of Ecology, University of Innsbruck, Technikerstr. 25, Innsbruck, 6020, Austria
| | - Birgit C Schlick-Steiner
- Molecular Ecology Group, Department of Ecology, University of Innsbruck, Technikerstr. 25, Innsbruck, 6020, Austria
| | - Florian M Steiner
- Molecular Ecology Group, Department of Ecology, University of Innsbruck, Technikerstr. 25, Innsbruck, 6020, Austria
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8
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Avril A, Purcell J, Brelsford A, Chapuisat M. Asymmetric assortative mating and queen polyandry are linked to a supergene controlling ant social organization. Mol Ecol 2018; 28:1428-1438. [PMID: 30003603 DOI: 10.1111/mec.14793] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 07/02/2018] [Accepted: 07/06/2018] [Indexed: 01/04/2023]
Abstract
Nonrecombining genomic variants underlie spectacular social polymorphisms, from bird mating systems to ant social organization. Because these "social supergenes" affect multiple phenotypic traits linked to survival and reproduction, explaining their persistence remains a substantial challenge. Here, we investigate how large nonrecombining genomic variants relate to colony social organization, mating system and dispersal in the Alpine silver ant, Formica selysi. The species has colonies headed by a single queen (monogynous) and colonies headed by multiple queens (polygynous). We confirmed that a supergene with alternate haplotypes-Sm and Sp-underlies this polymorphism in social structure: Females from mature monogynous colonies had the Sm/Sm genotype, while those from polygynous colonies were Sm/Sp and Sp/Sp. Queens heading monogynous colonies were exclusively mated with Sm males. In contrast, queens heading polygynous colonies were mated with Sp males and Sm males. Sm males, which are only produced by monogynous colonies, accounted for 22.9% of the matings with queens from mature polygynous colonies. This asymmetry between social forms in the degree of assortative mating generates unidirectional male-mediated gene flow from the monogynous to the polygynous social form. Biased gene flow was confirmed by a significantly higher number of private alleles in the polygynous social form. Moreover, heterozygous queens were three times as likely as homozygous queens to be multiply mated. This study reveals that the supergene variants jointly affect social organization and multiple components of the mating system that alter the transmission of the variants and thus influence the dynamics of the system.
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Affiliation(s)
- Amaury Avril
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Jessica Purcell
- Department of Entomology, University of California Riverside, Riverside, California
| | - Alan Brelsford
- Department of Evolution, Ecology, and Organismal Biology, University of California Riverside, Riverside, California
| | - Michel Chapuisat
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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9
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Krapf P, Russo L, Arthofer W, Möst M, Steiner FM, Schlick-Steiner BC. An Alpine ant's behavioural polymorphism: monogyny with and without internest aggression in Tetramorium alpestre. ETHOL ECOL EVOL 2017; 30:220-234. [PMID: 29682632 PMCID: PMC5890305 DOI: 10.1080/03949370.2017.1343868] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 05/31/2017] [Indexed: 11/21/2022]
Abstract
Social structure influences animal societies on various levels (e.g., relatedness, behaviour). In ants, both the number of matings per queen and the number of queens per colony can vary strongly. While workers from both monogynous and polygynous colonies often fight fiercely, in supercolonies (an extreme form of polygyny comprising thousands of queens in spatially separated but interconnected nests), non-nestmates interact peacefully. Studies on social and behavioural polymorphism within ant species can help elucidate their influence on genetic diversity and behaviour and the factors triggering variation in social structure and behaviour. Here, we reveal a behavioural and social polymorphism comprising monogyny with and without internest aggression in Tetramorium alpestre sampled in Tyrol, Austria. The social polymorphism is based on genetic and behavioural evidence and contrasts with the supercolonial organisation known from another location in Austria (Carinthia), 150 km away. Microsatellite genotyping using eight polymorphic loci revealed monogyny-monandry and high intranest pairwise relatedness. Interestingly, various experimental one-on-one worker encounters revealed only occasional aggressive behaviour between monogynous colonies, and thus a behavioural polymorphism. Mantel tests revealed a significant negative correlation between spatial distance and relatedness, while worker behaviour was not correlated with relatedness or spatial distance. These results indicate that behaviour might be influenced by other factors - for example, the experience of workers, ecological, chemical, and/or genetic factors not characterised in this study. However, workers distinguished nestmates from non-nestmates also when aggression was lacking. We hypothesise an adaptive value of reduced aggression. We speculate that the non-aggressive and partly aggressive encounters observed represent different options in the social structure of T. alpestre, the non-aggressiveness possibly also promoting supercolony development. The social and behavioural polymorphisms observed offer opportunities to identify the factors triggering these changes and thus further explore the behavioural and social polymorphism of this ant species.
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Affiliation(s)
- Patrick Krapf
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
| | - Lucia Russo
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
| | - Wolfgang Arthofer
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
| | - Markus Möst
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
| | - Florian M. Steiner
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
| | - Birgit C. Schlick-Steiner
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
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10
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Beresford J, Elias M, Pluckrose L, Sundström L, Butlin RK, Pamilo P, Kulmuni J. Widespread hybridization within mound-building wood ants in Southern Finland results in cytonuclear mismatches and potential for sex-specific hybrid breakdown. Mol Ecol 2017; 26:4013-4026. [PMID: 28503905 DOI: 10.1111/mec.14183] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 04/07/2017] [Accepted: 04/17/2017] [Indexed: 12/28/2022]
Abstract
Hybridization and gene flow between diverging lineages are increasingly recognized as common evolutionary processes, and their consequences can vary from hybrid breakdown to adaptive introgression. We have previously found a population of wood ant hybrids between Formica aquilonia and F. polyctena that shows antagonistic effects of hybridization: females with introgressed alleles show hybrid vigour, whereas males with the same alleles show hybrid breakdown. Here, we investigate whether hybridization is a general phenomenon in this species pair and analyse 647 worker samples from 16 localities in Finland using microsatellite markers and a 1200-bp mitochondrial sequence. Our results show that 27 sampled nests contained parental-like gene pools (six putative F. polyctena and 21 putative F. aquilonia) and all remaining nests (69), from nine localities, contained hybrids of varying degrees. Patterns of genetic variation suggest these hybrids arise from several hybridization events or, instead, have backcrossed to the parental gene pools to varying extents. In contrast to expectations, the mitochondrial haplotypes of the parental species were not randomly distributed among the hybrids. Instead, nests that were closer to parental-like F. aquilonia for nuclear markers preferentially had F. polyctena's mitochondria and vice versa. This systematic pattern suggests there may be underlying selection favouring cytonuclear mismatch and hybridization. We also found a new hybrid locality with strong genetic differences between the sexes similar to those predicted under antagonistic selection on male and female hybrids. Further studies are needed to determine the selective forces that act on male and female genomes in these newly discovered hybrids.
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Affiliation(s)
- J Beresford
- Department of Biosciences, Centre of Excellence in Biological Interactions, University of Helsinki, Helsinki, Finland.,Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - M Elias
- Institut de Systématique, Évolution, Biodiversité (ISYEB) - UMR 7205 - CNRS MNHN UPMC EPHE, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France
| | - L Pluckrose
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - L Sundström
- Department of Biosciences, Centre of Excellence in Biological Interactions, University of Helsinki, Helsinki, Finland.,Tvärminne Zoological Station, University of Helsinki, Hanko, Finland
| | - R K Butlin
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.,Department of Marine Science, University of Gothenburg, Gothenburg, Sweden
| | - P Pamilo
- Department of Biosciences, Centre of Excellence in Biological Interactions, University of Helsinki, Helsinki, Finland
| | - J Kulmuni
- Department of Biosciences, Centre of Excellence in Biological Interactions, University of Helsinki, Helsinki, Finland.,Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.,Tvärminne Zoological Station, University of Helsinki, Hanko, Finland.,Department of Biology and Biocenter Oulu, University of Oulu, Oulu, Finland
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