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Pulliainen U, Morandin C, Bos N, Sundström L, Schultner E. Social environment affects sensory gene expression in ant larvae. INSECT MOLECULAR BIOLOGY 2022; 31:1-9. [PMID: 34418191 DOI: 10.1111/imb.12732] [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: 05/04/2021] [Revised: 07/08/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
Social insects depend on communication to regulate social behaviour. This also applies to their larvae, which are commonly exposed to social interactions and can react to social stimulation. However, how social insect larvae sense their environment is not known. Using RNAseq, we characterized expression of sensory-related genes in larvae of the ant Formica fusca, upon exposure to two social environments: isolation without contact to other individuals, and stimulation via the presence of other developing individuals. Expression of key sensory-related genes was higher following social stimulation, and larvae expressed many of the same sensory-related genes as adult ants and larvae of other insects, including genes belonging to the major insect chemosensory gene families. Our study provides first insights into the molecular changes associated with social information perception in social insect larvae.
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Affiliation(s)
- U Pulliainen
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- Tvärminne Zoological Station, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - C Morandin
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland
| | - N Bos
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- Department of Biology, Faculty of Sciences, University of Copenhagen, Copenhagen, Denmark
| | - L Sundström
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- Tvärminne Zoological Station, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - E Schultner
- Zoology and Evolutionary Biology, University of Regensburg, Regensburg, Germany
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2
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Similarities in Recognition Cues Lead to the Infiltration of Non-Nestmates in an Ant Species. J Chem Ecol 2021; 48:16-26. [PMID: 34762209 DOI: 10.1007/s10886-021-01325-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 10/12/2021] [Accepted: 10/17/2021] [Indexed: 10/19/2022]
Abstract
Chemical cues are among the most important information-sharing mechanisms in insect societies, in which cuticular hydrocarbons play a central role, e.g., from nestmate recognition to queen signaling. The nestmate recognition mechanism usually prevents intruders from taking advantage of the resources stored in the nest. However, nestmate recognition is not unconditionally effective, and foreign individuals can sometimes infiltrate unrelated nests and take advantage of the colony resources. In this study, we investigated the role of overall colony odor profiles on the ability of conspecific workers to drift into unrelated colonies. We hypothesized that drifters would have higher chances of success by infiltrating colonies with the odor profiles most similar to their own nest, avoiding being detected as non-nestmates. By performing a drifting bioassay, we found that workers of the ant Formica fusca infiltrated unrelated conspecific colonies at a rate of 2.4%, significantly infiltrating colonies displaying CHC profiles most similar to their natal nests. Notably, methyl branched hydrocarbons seem to play a role as recognition cues in this species. In addition, we show that environmental rather than genetic factors are responsible for most contributions on the CHC phenotype, presenting ca. of 50% and 27.5% of explained variation respectively, and playing a major role in how worker ants detect and prevent the infiltration of non-nestmates in the colony. Hence, relying on cuticular hydrocarbons similarities could be a profitably evolutionary strategy by which workers can identify conspecific colonies, evade detection by guards, and avoid competition with genetic relatives.
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3
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Eyer P, Shults PT, Chura MR, Moran MN, Thompson MN, Helms AM, Saran RK, Vargo EL. Divide and conquer: Multicolonial structure, nestmate recognition, and antagonistic behaviors in dense populations of the invasive ant Brachymyrmex patagonicus. Ecol Evol 2021; 11:4874-4886. [PMID: 33976855 PMCID: PMC8093738 DOI: 10.1002/ece3.7396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/05/2021] [Accepted: 02/18/2021] [Indexed: 02/01/2023] Open
Abstract
The ecological success of ants has made them abundant in most environments, yet inter- and intraspecific competition usually limit nest density for a given population. Most invasive ant populations circumvent this limitation through a supercolonial structure, eliminating intraspecific competition through a loss of nestmate recognition and lack of aggression toward non-nestmates. Native to South America, Brachymyrmex patagonicus has recently invaded many locations worldwide, with invasive populations described as extremely large and dense. Yet, in contrast with most invasive ants, this species exhibits a multicolonial structure, whereby each colony occupies a single nest. Here, we investigated the interplay between genetic diversity, chemical recognition, and aggressive behaviors in an invasive population of B. patagonicus. We found that, in its invasive range, this species reaches a high nest density with individual colonies located every 2.5 m and that colony boundaries are maintained through aggression toward non-nestmates. This recognition and antagonism toward non-nestmates is mediated by chemical differentiation between colonies, as different colonies exhibit distinct chemical profiles. We highlighted that the level of aggression between colonies is correlated with their degree of genetic difference, but not their overall chemical differentiation. This may suggest that only a few chemical compounds influence nestmate recognition in this species or that weak chemical differences are sufficient to elicit aggression. Overall, this study demonstrates that invasive ant populations can reach high densities despite a multicolonial structure with strong aggression between colonies, raising questions about the factors underlying their ecological success and mitigating negative consequences of competitive interactions.
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Affiliation(s)
| | | | | | - Megan N. Moran
- Department of EntomologyTexas A&M UniversityCollege StationTXUSA
| | | | - Anjel M. Helms
- Department of EntomologyTexas A&M UniversityCollege StationTXUSA
| | - Raj K. Saran
- Bayer Environmental SciencesCollege StationTXUSA
| | - Edward L. Vargo
- Department of EntomologyTexas A&M UniversityCollege StationTXUSA
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4
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Peignier M, Pokorny T, Heinze J, Lindgren R, Helanterä H, Schultner E. Honesty of Larval Begging Signals Covaries With Colony Kin Structure in Formica Ants. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00398] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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5
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Phenotypic Plasticity of Nest-Mate Recognition Cues in Formica exsecta Ants. J Chem Ecol 2019; 45:735-740. [PMID: 31475301 PMCID: PMC6754345 DOI: 10.1007/s10886-019-01103-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 08/17/2019] [Accepted: 08/22/2019] [Indexed: 11/07/2022]
Abstract
It is well established that many ant species have evolved qualitatively distinct species-specific chemical profile that are stable over large geographical distances. Within these species profiles quantitative variations in the chemical profile allows distinct colony-specific odours to arise (chemotypes) that are shared by all colony members. This help maintains social cohesion, including defence of their colonies against all intruders, including con-specifics. How these colony -level chemotypes are maintained among nest-mates has long been debated. The two main theories are; each ant is able to biochemically adjust its chemical profile to ‘match’ that of its nest-mates and or the queen, or all nest-mates share their individually generated chemical profile via trophollaxis resulting in an average nest-mate profile. This ‘mixing’ idea is better known as the Gestalt model. Unfortunately, it has been very difficult to experimentally test these two ideas in a single experimental design. However, it is now possible using the ant Formica exsecta because the compounds used in nest-mate recognition compounds are known. We demonstrate that workers adjust their profile to ‘match’ the dominant chemical profile within that colony, hence maintaining the colony-specific chemotype and indicates that a ‘gestalt’ mechanism, i.e. profile mixing, plays no or only a minor role.
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6
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Pulliainen U, Helanterä H, Sundström L, Schultner E. The possible role of ant larvae in the defence against social parasites. Proc Biol Sci 2019; 286:20182867. [PMID: 30836870 PMCID: PMC6458323 DOI: 10.1098/rspb.2018.2867] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 02/07/2019] [Indexed: 10/27/2022] Open
Abstract
Temporary social parasite ant queens initiate new colonies by entering colonies of host species, where they begin laying eggs. As the resident queen can be killed during this process, host colonies may lose their entire future reproductive output. Selection thus favours the evolution of defence mechanisms, before and after parasite intrusion. Most studies on social parasites focus on host worker discrimination of parasite queens and their offspring. However, ant larvae can also influence brood composition by consuming eggs. This raises the question whether host larvae can aid in preventing colony takeover by consuming eggs laid by parasite queens. To test whether larvae could play a role in anti-parasite defence, we compared the rates at which larvae of a common host species, Formica fusca, consumed eggs laid by social parasite, non-parasite, nest-mate, or conspecific non-nest-mate queens. Larvae consumed social parasite eggs more than eggs laid by a heterospecific non-parasite queen, irrespective of the chemical distance between the egg cuticular profiles. Also, larvae consumed eggs laid by conspecific non-nest-mate queens more than those laid by nest-mate queens. Our study suggests that larvae may act as players in colony defence against social parasitism, and that social parasitism is a key factor shaping discrimination behaviour in ants.
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Affiliation(s)
- Unni Pulliainen
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
- Tvärminne Zoological Station, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
| | - Heikki Helanterä
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
- Tvärminne Zoological Station, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
- Ecology and Genetics Research Unit, Faculty of Science, University of Oulu, Finland
| | - Liselotte Sundström
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
- Tvärminne Zoological Station, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
| | - Eva Schultner
- Institut für Zoologie und Evolutionsbiologie, Biologie I, Universität Regensburg, Regensburg, Germany
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7
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Saar M, Eyer PA, Kilon-Kallner T, Hefetz A, Scharf I. Within-colony genetic diversity differentially affects foraging, nest maintenance, and aggression in two species of harvester ants. Sci Rep 2018; 8:13868. [PMID: 30217995 PMCID: PMC6138738 DOI: 10.1038/s41598-018-32064-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 09/03/2018] [Indexed: 11/09/2022] Open
Abstract
There is accumulating evidence that genetic diversity improves the behavioral performance and consequently the fitness in groups of social animals. We examined the behavioral performance of colonies of two co-occurring, congeneric harvester ant species (Messor arenarius and a non-described Messor sp.) in fitness-related behaviors, pertaining to foraging performance, nest maintenance, and aggression. We linked these behaviors to the colonial genetic diversity, by genotyping workers, using six and five microsatellite markers for M. arenarius and M. sp., respectively. Correlations of genetic diversity with colony performance and aggression level contrasted between the two species. In M. arenarius, genetic diversity was correlated with foraging performance and nest maintenance but not with the overall aggression level, while in M. sp., genetic diversity was correlated with the overall aggression level, but not with foraging performance or nest maintenance. The two species exhibited similar specific aggression levels, with higher aggression shown towards heterospecifics and lower towards non-nestmate conspecifics and nestmates. However, M. sp. workers displayed a tendency to interact for longer with heterospecifics than did M. arenarius. We speculate that the different foraging strategies, group vs. individual foraging, and possibly also the different mating systems, contribute to the differences found in behavior between the two species.
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Affiliation(s)
- Maya Saar
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Pierre-André Eyer
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Department of Entomology, Texas A&M University, College Station, Texas, USA
| | - Tal Kilon-Kallner
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Abraham Hefetz
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Inon Scharf
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
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8
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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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9
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Ellis S, Procter DS, Buckham-Bonnett P, Robinson EJH. Inferring polydomy: a review of functional, spatial and genetic methods for identifying colony boundaries. INSECTES SOCIAUX 2016; 64:19-37. [PMID: 28255180 PMCID: PMC5310590 DOI: 10.1007/s00040-016-0534-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 11/04/2016] [Accepted: 11/06/2016] [Indexed: 06/06/2023]
Abstract
Identifying the boundaries of a social insect colony is vital for properly understanding its ecological function and evolution. Many species of ants are polydomous: colonies inhabit multiple, spatially separated, nests. Ascertaining which nests are parts of the same colony is an important consideration when studying polydomous populations. In this paper, we review the methods that are used to identify which nests are parts of the same polydomous colony and to determine the boundaries of colonies. Specifically, we define and discuss three broad categories of approach: identifying nests sharing resources, identifying nests sharing space, and identifying nests sharing genes. For each of these approaches, we review the theoretical basis, the limitations of the approach and the methods that can be used to implement it. We argue that all three broad approaches have merits and weaknesses, and provide a methodological comparison to help researchers select the tool appropriate for the biological question they are investigating.
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Affiliation(s)
- S. Ellis
- Department of Biology and York Centre for Complex Systems Analysis, University of York, York, UK
- Centre for Research in Animal Behaviour, University of Exeter, Exeter, UK
| | - D. S. Procter
- Department of Biology and York Centre for Complex Systems Analysis, University of York, York, UK
- Centre for Exercise, Nutrition and Health Sciences, School of Policy Studies, University of Bristol, Bristol, UK
| | - P. Buckham-Bonnett
- Department of Biology and York Centre for Complex Systems Analysis, University of York, York, UK
| | - E. J. H. Robinson
- Department of Biology and York Centre for Complex Systems Analysis, University of York, York, UK
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10
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Menzel F, Radke R, Foitzik S. Odor diversity decreases with inbreeding in the ant Hypoponera opacior. Evolution 2016; 70:2573-2582. [PMID: 27641363 DOI: 10.1111/evo.13068] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 08/22/2016] [Accepted: 08/23/2016] [Indexed: 12/29/2022]
Abstract
Reduction in heterozygosity can lead to inbreeding depression. This loss of genetic variability especially affects diverse loci, such as immune genes or those encoding recognition cues. In social insects, nestmates are recognized by their odor, that is their cuticular hydrocarbon profile. Genes underlying hydrocarbon production are thought to be under balancing selection. If so, inbreeding should result in a loss of chemical diversity. We show here that cuticular hydrocarbon diversity decreases with inbreeding. Studying an ant with a facultative inbreeding lifestyle, we found inbred workers to exhibit both a lower number of hydrocarbons and less diverse, that is less evenly proportioned profiles. The association with inbreeding was strong for methyl-branched alkanes, which play a major role in nestmate recognition, and for n-alkanes, whereas unsaturated compounds were unaffected. Shifts in allocation strategies with inbreeding in our focal species indicate that these ants can detect their inbreeding level and use this information to adjust their reproductive strategy. Our study is the first to demonstrate that odor profiles can encode information on inbreeding, with broad implications not only for social insects, but for sexual selection and mate choice in general. Odor profiles may constitute an honest signal of inbreeding, a fitness-relevant trait in many species.
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Affiliation(s)
- Florian Menzel
- Institute of Zoology, Johannes Gutenberg University Mainz, Johannes-von-Müller-Weg 6, 55128, Mainz, Germany.
| | - René Radke
- Institute of Zoology, Johannes Gutenberg University Mainz, Johannes-von-Müller-Weg 6, 55128, Mainz, Germany
| | - Susanne Foitzik
- Institute of Zoology, Johannes Gutenberg University Mainz, Johannes-von-Müller-Weg 6, 55128, Mainz, Germany
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11
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Leonhardt SD, Menzel F, Nehring V, Schmitt T. Ecology and Evolution of Communication in Social Insects. Cell 2016; 164:1277-1287. [PMID: 26967293 DOI: 10.1016/j.cell.2016.01.035] [Citation(s) in RCA: 186] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Indexed: 01/06/2023]
Abstract
Insect life strategies comprise all levels of sociality from solitary to eusocial, in which individuals form persistent groups and divide labor. With increasing social complexity, the need to communicate a greater diversity of messages arose to coordinate division of labor, group cohesion, and concerted actions. Here we summarize the knowledge on prominent messages in social insects that inform about reproduction, group membership, resource locations, and threats and discuss potential evolutionary trajectories of each message in the context of social complexity.
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Affiliation(s)
- Sara Diana Leonhardt
- Department of Animal Ecology and Tropical Biology, University of Würzburg, 97074 Würzburg, Germany
| | - Florian Menzel
- Evolutionary Biology, Institute of Zoology, University of Mainz, 55128 Mainz, Germany
| | - Volker Nehring
- Department of Evolutionary Biology and Animal Ecology, University of Freiburg, 79104 Freiburg, Germany
| | - Thomas Schmitt
- Department of Animal Ecology and Tropical Biology, University of Würzburg, 97074 Würzburg, Germany.
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12
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Social Structure and Genetic Distance Mediate Nestmate Recognition and Aggressiveness in the Facultative Polygynous Ant Pheidole pallidula. PLoS One 2016; 11:e0156440. [PMID: 27243627 PMCID: PMC4886963 DOI: 10.1371/journal.pone.0156440] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 05/13/2016] [Indexed: 11/19/2022] Open
Abstract
In social insects, the evolutionary stability of cooperation depends on the privileged relationships between individuals of the social group, which is facilitated by the recognition of relatives. Nestmate recognition is based on genetically determined cues and/or environmentally derived chemical components present on the cuticle of individuals. Here, we studied nestmate recognition in the ant Pheidole pallidula, a species where both single-queen (monogyne) and multiple-queen (polygyne) colonies co-occur in the same population. We combined geographical, genetic and chemical analyses to disentangle the factors influencing the level of intraspecific aggressiveness. We show that encounters between workers from neighbouring colonies (i.e., nests less than 5 m away) are on average less aggressive than those between workers from more distant colonies. Aggressive behaviour is associated with the level of genetic difference: workers from monogyne colonies are more aggressive than workers from polygyne colonies, and the intensity of aggressiveness is positively associated with the genetic distance between colonies. Since the genetic distance is correlated with the spatial distance between pairs of colonies, the lower level of aggression toward neighbours may result from their higher relatedness. In contrast, the analysis of overall cuticular hydrocarbon profiles shows that aggressive behaviour is associated neither with the chemical diversity of colonies, nor with the chemical distances between them. When considering methyl-branched alkanes only, however, chemical distances differed between monogyne and polygyne colonies and were significantly associated with aggressiveness. Altogether, these results show that the social structure of colonies and the genetic distances between colonies are two major factors influencing the intensity of agonistic behaviours in the ant P. pallidula.
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13
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Torres CW, Tsutsui ND. The Effect of Social Parasitism by Polyergus breviceps on the Nestmate Recognition System of Its Host, Formica altipetens. PLoS One 2016; 11:e0147498. [PMID: 26840394 PMCID: PMC4740506 DOI: 10.1371/journal.pone.0147498] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 01/04/2016] [Indexed: 11/30/2022] Open
Abstract
Highly social ants, bees and wasps employ sophisticated recognition systems to identify colony members and deny foreign individuals access to their nest. For ants, cuticular hydrocarbons serve as the labels used to ascertain nest membership. Social parasites, however, are capable of breaking the recognition code so that they can thrive unopposed within the colonies of their hosts. Here we examine the influence of the socially parasitic slave-making ant, Polyergus breviceps on the nestmate recognition system of its slaves, Formica altipetens. We compared the chemical, genetic, and behavioral characteristics of colonies of enslaved and free-living F. altipetens. We found that enslaved Formica colonies were more genetically and chemically diverse than their free-living counterparts. These differences are likely caused by the hallmark of slave-making ant ecology: seasonal raids in which pupa are stolen from several adjacent host colonies. The different social environments of enslaved and free-living Formica appear to affect their recognition behaviors: enslaved Formica workers were less aggressive towards non-nestmates than were free-living Formica. Our findings indicate that parasitism by P. breviceps dramatically alters both the chemical and genetic context in which their kidnapped hosts develop, leading to changes in how they recognize nestmates.
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Affiliation(s)
- Candice W. Torres
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, United States of America
- * E-mail:
| | - Neil D. Tsutsui
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, United States of America
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14
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Frizzi F, Ciofi C, Dapporto L, Natali C, Chelazzi G, Turillazzi S, Santini G. The Rules of Aggression: How Genetic, Chemical and Spatial Factors Affect Intercolony Fights in a Dominant Species, the Mediterranean Acrobat Ant Crematogaster scutellaris. PLoS One 2015; 10:e0137919. [PMID: 26445245 PMCID: PMC4596555 DOI: 10.1371/journal.pone.0137919] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Accepted: 08/23/2015] [Indexed: 12/04/2022] Open
Abstract
Nest-mate recognition plays a key role in the biology of ants. Although individuals coming from a foreign nest are, in most cases, promptly rejected, the degree of aggressiveness towards non nest-mates may be highly variable among species and relies on genetic, chemical and environmental factors. We analyzed intraspecific relationships among neighboring colonies of the dominant Mediterranean acrobat ant Crematogaster scutellaris integrating genetic, chemical and behavioral analyses. Colony structure, parental relationships between nests, cuticular hydrocarbons profiles (CHCs) and aggressive behavior against non nest-mates were studied in 34 nests located in olive tree trunks. Bayesian clustering analysis of allelic variation at nine species-specific microsatellite DNA markers pooled nests into 14 distinct clusters, each representing a single colony, confirming a polydomous arrangement of nests in this species. A marked genetic separation among colonies was also detected, probably due to long distance dispersion of queens and males during nuptial flights. CHCs profiles varied significantly among colonies and between nests of the same colony. No relationship between CHCs profiles and genetic distances was detected. The level of aggressiveness between colonies was inversely related to chemical and spatial distance, suggesting a ‘nasty neighbor’ effect. Our findings also suggest that CHCs profiles in C. scutellaris may be linked to external environmental factors rather than genetic relationships.
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Affiliation(s)
- Filippo Frizzi
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019, Sesto Fiorentino (FI), Italy
- * E-mail:
| | - Claudio Ciofi
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019, Sesto Fiorentino (FI), Italy
| | - Leonardo Dapporto
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019, Sesto Fiorentino (FI), Italy
| | - Chiara Natali
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019, Sesto Fiorentino (FI), Italy
| | - Guido Chelazzi
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019, Sesto Fiorentino (FI), Italy
| | - Stefano Turillazzi
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019, Sesto Fiorentino (FI), Italy
| | - Giacomo Santini
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019, Sesto Fiorentino (FI), Italy
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15
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Jongepier E, Foitzik S. Ant recognition cue diversity is higher in the presence of slavemaker ants. Behav Ecol 2015. [DOI: 10.1093/beheco/arv153] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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Helanterä H, d'Ettorre P. A comparative study of egg recognition signature mixtures in Formica ants. Evolution 2015; 69:520-9. [PMID: 25545864 DOI: 10.1111/evo.12590] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Accepted: 12/04/2014] [Indexed: 11/28/2022]
Abstract
Processing of information from the environment, such as assessing group membership in social contexts, is a major determinant of inclusive fitness. For social insects, recognizing brood origin is crucial for inclusive fitness in many contexts, such as social parasitism and kin conflicts within colonies. Whether a recognition signature is informative in kin conflicts depends on the extent of a genetic contribution into the cues. We investigated colony- and matriline-specific variation in egg surface hydrocarbons in seven species of Formica ants. We show that chemical variance is distributed similarly to genetic variation, suggesting a significant genetic contribution to eggs odors in the genus. Significant among matriline components, and significant correlations between chemical and genetic similarity among individuals also indicate kin informative egg odors in several species. We suggest that egg odor surface variation could play a large role in within colony conflicts, and that a comparative method can reveal novel insight into communication of identity.
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Affiliation(s)
- Heikki Helanterä
- Centre of Excellence in Biological Interactions, Department of Bioscience, University of Helsinki, Helsinki, Finland; Tvärminne Zoological Station, University of Helsinki, Helsinki, Finland.
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Population Diversity in Cuticular Hydrocarbons and mtDNA in a Mountain Social Wasp. J Chem Ecol 2014; 41:22-31. [DOI: 10.1007/s10886-014-0531-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 11/03/2014] [Accepted: 11/12/2014] [Indexed: 10/24/2022]
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Sources of variation in cuticular hydrocarbons in the ant Formica exsecta. J Chem Ecol 2013; 39:1415-23. [PMID: 24272518 PMCID: PMC3851696 DOI: 10.1007/s10886-013-0366-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/23/2013] [Accepted: 10/08/2013] [Indexed: 01/09/2023]
Abstract
Phenotypic variation arises from interactions between genotype and environment, although how variation is produced and then maintained remains unclear. The discovery of the nest-mate recognition system in Formica exsecta ants has allowed phenotypic variation in chemical profiles to be quantified across a natural population of 83 colonies. We investigated if this variation was correlated or not with intrinsic (genetic relatedness), extrinsic (location, light, temperature), or social (queen number) factors. (Z)-9-Alkenes and n-alkanes showed different patterns of variance: island (location) explained only 0.2 % of the variation in (Z)-9-alkenes, but 21-29 % in n-alkanes, whereas colony of origin explained 96 % and 45-49 % of the variation in (Z)-9-alkenes and n-alkanes, respectively. By contrast, within-colony variance of (Z)-9-alkenes was 4 %, and 23-34 % in n-alkanes, supporting the function of the former as recognition cues. (Z)-9-Alkene and n-alkane profiles were correlated with the genetic distance between colonies. Only n-alkane profiles diverged with increasing spatial distance. Sampling year explained a small (5 %), but significant, amount of the variation in the (Z)-9-alkenes, but there was no consistent directional trend. Polygynous colonies and populous monogynous colonies were dominated by a rich C23:1 profile. We found no associations between worker size, mound exposure, or humidity, although effect sizes for the latter two factors were considerable. The results support the conjecture that genetic factors are the most likely source of between-colony variation in cuticular hydrocarbons.
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Badouin H, Belkhir K, Gregson E, Galindo J, Sundström L, Martin SJ, Butlin RK, Smadja CM. Transcriptome characterisation of the ant Formica exsecta with new insights into the evolution of desaturase genes in social hymenoptera. PLoS One 2013; 8:e68200. [PMID: 23874539 PMCID: PMC3709892 DOI: 10.1371/journal.pone.0068200] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 05/28/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Despite the recent sequencing of seven ant genomes, no genomic data are available for the genus Formica, an important group for the study of eusocial traits. We sequenced the transcriptome of the ant Formica exsecta with the 454 FLX Titanium technology from a pooled sample of workers from 70 Finnish colonies. RESULTS About 1,000,000 reads were obtained from a normalised cDNA library. We compared the assemblers MIRA3.0 and Newbler2.6 and showed that the latter performed better on this dataset due to a new option which is dedicated to improve contig formation in low depth portions of the assemblies. The 29,579 contigs represent 27 Mb. 50% showed similarity with known proteins and 25% could be assigned a category of gene ontology. We found more than 13,000 high-quality single nucleotide polymorphisms. The Δ9 desaturase gene family is an important multigene family involved in chemical communication in insects. We found six Δ9 desaturases in this Formica exsecta transcriptome dataset that were used to reconstruct a maximum-likelihood phylogeny of insect desaturases and to test for signatures of positive selection in this multigene family in ant lineages. We found differences with previous phylogenies of this gene family in ants, and found two clades potentially under positive selection. CONCLUSION This first transcriptome reference sequence of Formica exsecta provided sequence and polymorphism data that will allow researchers working on Formica ants to develop studies to tackle the genetic basis of eusocial phenotypes. In addition, this study provided some general guidelines for de novo transcriptome assembly that should be useful for future transcriptome sequencing projects. Finally, we found potential signatures of positive selection in some clades of the Δ9 desaturase gene family in ants, which suggest the potential role of sequence divergence and adaptive evolution in shaping the large diversity of chemical cues in social insects.
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Affiliation(s)
- Hélène Badouin
- Centre National de la Recherche Scientifique CNRS - Institut des Sciences de l'Evolution UMR 5554, Université Montpellier 2, Montpellier, France.
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Abstract
Communication between organisms involves visual, auditory, and olfactory pathways. In solitary insects, chemical recognition cues are influenced mainly by selection regimes related to species recognition and sexual selection. In social insects, chemical recognition cues have an additional role in mediating recognition of society members and, thereby, allowing kin selection to operate. Here, we examined whether cuticular hydrocarbon profiles are sex-specific and whether males and young queens of the ant Formica fusca have colony-specific profiles. We also investigated whether there is a relationship between genetic relatedness and chemical diversity within colonies. We demonstrated that female and male sexuals do not have unique sex-specific compounds, but that there are quantitative chemical differences between the sexes. Out of the 51 cuticular hydrocarbon compounds identified, 10 showed a significant quantitative difference between males and females. We also showed that both males and females have a significant colony-specific component in their profiles. Finally, we found a negative correlation between within-colony relatedness and within-colony chemical diversity of branched, but not linear compounds. This suggests that colonies with multiple matri- or patrilines also have a significantly greater chemical diversity.
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Martin S, Trontti K, Shemilt S, Drijfhout F, Butlin R, Jackson D. Weak patriline effects are present in the cuticular hydrocarbon profiles of isolated Formica exsecta ants but they disappear in the colony environment. Ecol Evol 2012; 2:2333-46. [PMID: 23139891 PMCID: PMC3488683 DOI: 10.1002/ece3.319] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 06/15/2012] [Accepted: 06/18/2012] [Indexed: 11/24/2022] Open
Abstract
Chemical recognition cues are used to discriminate among species, con-specifics, and potentially between patrilines in social insect colonies. There is an ongoing debate about the possible persistence of patriline cues despite evidence for the mixing of colony odors via a “gestalt” mechanism in social insects, because patriline recognition could lead to nepotism. We analyzed the variation in recognition cues (cuticular hydrocarbons) with different mating frequencies or queen numbers in 688 Formica exsecta ants from 76 colonies. We found no increase in the profile variance as genetic diversity increased, indicating that patriline effects were absent or possibly obscured by a gestalt mechanism. We then demonstrated that an isolated individual's profile changed considerably relative to their colony profile, before stabilizing after 5 days. We used these isolated individuals to eliminate the masking effects of the gestalt mechanism, and we detected a weak but statistically significant patriline effect in isolated adult workers and also in newly emerged callow workers. Thus, our evidence suggests that genetic variation in the cuticular hydrocarbon profile of F. exsecta ants (n-alkanes and alkenes) resulted in differences among patrilines, but they were obscured in the colony environment, thereby avoiding costly nepotistic behaviors.
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Affiliation(s)
- Stephen Martin
- Department of Animal & Plant Sciences, University of Sheffield Sheffield, S10 2TN, U.K
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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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Martin SJ, Vitikainen E, Drijfhout FP, Jackson D. Conspecific ant aggression is correlated with chemical distance, but not with genetic or spatial distance. Behav Genet 2011; 42:323-31. [PMID: 21928047 DOI: 10.1007/s10519-011-9503-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 09/08/2011] [Indexed: 10/17/2022]
Abstract
Five possible mechanisms might underlie kin recognition in social groups: spatial location, familiarity through prior association, phenotype matching, recognition alleles, or rejecting unfamiliar cues. Kin recognition by phenotype matching relies on a strong correlation between genotype and phenotype. Aggression bioassays are the standard method for investigating recognition in animals, particularly social insect interactions among nestmates and non-nestmates. These bioassays typically pay little regard to how outcomes are determined by differences in chemical recognition cues of the test subjects, because the system of signal coding was unknown until recently. We exploited the known nestmate recognition system of the ant Formica exsecta to investigate aggression between 24 pairs of colonies across a range of chemical (Z9-alkene & n-alkanes), genetic, and spatial distances. The whole Z9-alkene chemical profile was the only significant (p < 0.001) predictor of aggression levels. Aggression was a nonlinear step function of Z9-alkene chemical distance, where a small change in chemical profile resulted in a rapid behavioural transition from non-aggression to overt aggression. These findings raise questions surrounding our current understanding of recognition systems, because they support phenotype matching to a colony chemical profile without a significant genetic or spatial component.
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Affiliation(s)
- Stephen J Martin
- Department of Animal & Plant Sciences, University of Sheffield, Sheffield, UK.
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