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Krapf P, Sedfaoui K, Contala ML, Steiner FM, Schlick-Steiner BC. Short-time development of among-colony behaviour in a high-elevation ant. Behav Processes 2023; 208:104872. [PMID: 37011703 DOI: 10.1016/j.beproc.2023.104872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 03/25/2023] [Accepted: 03/30/2023] [Indexed: 04/03/2023]
Abstract
Standardised assays are often used to characterise aggression in animals. In ants,such assays can be applied at several organisational levels (e.g., colony, population) and at specific times during the season. However, whether the behaviour differs at these levels and changes over a few weeks remains largely unexplored. Here, six colonies from the high-elevation ant Tetramorium alpestre were collected weekly for five weeks from two behaviourally-different populations (aggressive and peaceful in intraspecific encounters). We conducted one-on-one worker encounters at the colony and population levels. When analysing the colony combinations separately, the behaviour was peaceful and remained so within the peaceful population; initial aggression became partially peaceful within the aggressive population; and initial aggression decreased occasionally and increased in one combination but remained constant for most across-population combinations. When analysing all colony combinations together, within-population behaviour remained similar, but acrosspopulation behaviour became peaceful. The observed behavioural differences among organisational levels emphasise the relevance of assessing both. Moreover, the effect of decreasing aggression is discernible already over a few weeks. Compression of the vegetation period at high elevations may compress such behavioural changes.Addressing both organisational levels and seasonality is important, particularly in studies of behavioural complexity such as in this ant.
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Affiliation(s)
- Patrick Krapf
- Molecular Ecology Group, Department of Ecology, Universität Innsbruck, Austria.
| | - Klaus Sedfaoui
- Molecular Ecology Group, Department of Ecology, Universität Innsbruck, Austria; Department of Biology, University of Padua, Italy
| | - Marie-Luise Contala
- Molecular Ecology Group, Department of Ecology, Universität Innsbruck, Austria
| | - Florian M Steiner
- Molecular Ecology Group, Department of Ecology, Universität Innsbruck, Austria
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Krapf P, Arthofer W, Ayasse M, Steiner FM, Schlick-Steiner BC. Global change may make hostile - Higher ambient temperature and nitrogen availability increase ant aggression. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 861:160443. [PMID: 36436655 DOI: 10.1016/j.scitotenv.2022.160443] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 10/24/2022] [Accepted: 11/19/2022] [Indexed: 06/16/2023]
Abstract
Behaviour is a response of organisms to internal and external stimuli and comprises various activities such as searching for food. Aggression is important in such activities, for example, improving the chances of winning competition for food, but animals differ in their level of aggression. This behavioural plasticity allows individuals to respond to environmental changes and is important for the survival of animals. It may be an important asset in facing global changes, which affect all organisms, for example, via rising temperature and eutrophication. The latter have steadily increased since 1900, especially in high elevations. Their effects may first become visible in stationary organisms such as ants because their nests are strictly associated with the conditions on site. Here, we analysed eight populations of the high-elevation ant Tetramorium alpestre along several elevations spanning the European Alps. We conducted a correlative approach and analysed several genetic and environmental proxies, namely within- and across-colony genetic relatedness, cuticular hydrocarbons, body size, across-colony geographic distance, air temperature, and worker nitrogen values additionally to within-population aggressive behaviour. We hypothesised that a) these proxies and aggressive behaviour differ among populations and that b) one or more of these proxies influence aggression. We found that a) some environmental proxies and aggression differed among populations but not the genetic proxies and that b) air temperature and worker nitrogen-isotope values correlated positively with worker aggression. The results indicate an environmental but not social-structural influence on this ant's aggressive behaviour, even though social structure varied among populations (single- and multiple-queened colonies). We infer that global change affects aggression in our study system and propose five mutually non-exclusive scenarios to explain the behavioural change mechanistically. Using the space-for-time principle, we speculate that aggression may increase due to future increases in temperature and nitrogen availability in this ant and other species living in high elevations.
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Affiliation(s)
- Patrick Krapf
- 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
| | - Manfred Ayasse
- Institute of Evolutionary Ecology and Conservation Genomics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Florian M Steiner
- 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
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Flucher SM, Krapf P, Arthofer W, Suarez AV, Crozier RH, Steiner FM, Schlick-Steiner BC. Effect of social structure and introduction history on genetic diversity and differentiation. Mol Ecol 2021; 30:2511-2527. [PMID: 33811410 DOI: 10.1111/mec.15911] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 03/03/2021] [Accepted: 03/19/2021] [Indexed: 12/31/2022]
Abstract
Invasive species are a global threat to biodiversity, and understanding their history and biology is a major goal of invasion biology. Population-genetic approaches allow insights into these features, as population structure is shaped by factors such as invasion history (number, origin and age of introductions) and life-history traits (e.g., mating system, dispersal capability). We compared the relative importance of these factors by investigating two closely related ants, Tetramorium immigrans and Tetramorium tsushimae, that differ in their social structure and invasion history in North America. We used mitochondrial DNA sequences and microsatellite alleles to estimate the source and number of introduction events of the two species, and compared genetic structure among native and introduced populations. Genetic diversity of both species was strongly reduced in introduced populations, which also differed genetically from native populations. Genetic differentiation between ranges and the reduction in microsatellite diversity were more severe in the more recently introduced and supercolonial T. tsushimae. However, the loss of mitochondrial haplotype diversity was more pronounced in T. immigrans, which has single-queen colonies and was introduced earlier. Tetramorium immigrans was introduced at least twice from Western Europe to North America and once independently to South America. Its monogyny might have limited genetic diversity per introduction, but new mutations and successive introductions over a long time may have added to the gene pool in the introduced range. Polygyny in T. tsushimae probably facilitated the simultaneous introduction of several queens from a Japanese population to St. Louis, USA. In addition to identifying introduction pathways, our results reveal how social structure can influence the population-genetic consequences of founder events.
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Affiliation(s)
- Sylvia M Flucher
- Molecular Ecology Group, Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Patrick Krapf
- Molecular Ecology Group, Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Wolfgang Arthofer
- Molecular Ecology Group, Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Andrew V Suarez
- Department of Evolution, Ecology and Behavior, University of Illinois at Urbana-Champaign, Urbana, IL, USA.,Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Ross H Crozier
- School of Marine and Tropical Biology, James Cook University, Townsville, QLD, Australia
| | - Florian M Steiner
- Molecular Ecology Group, Department of Ecology, University of Innsbruck, Innsbruck, Austria
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Cicconardi F, Krapf P, D'Annessa I, Gamisch A, Wagner HC, Nguyen AD, Economo EP, Mikheyev AS, Guénard B, Grabherr R, Andesner P, Wolfgang A, Di Marino D, Steiner FM, Schlick-Steiner BC. Genomic Signature of Shifts in Selection in a Subalpine Ant and Its Physiological Adaptations. Mol Biol Evol 2021; 37:2211-2227. [PMID: 32181804 PMCID: PMC7403626 DOI: 10.1093/molbev/msaa076] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Understanding how organisms adapt to extreme environments is fundamental and can provide insightful case studies for both evolutionary biology and climate-change biology. Here, we take advantage of the vast diversity of lifestyles in ants to identify genomic signatures of adaptation to extreme habitats such as high altitude. We hypothesized two parallel patterns would occur in a genome adapting to an extreme habitat: 1) strong positive selection on genes related to adaptation and 2) a relaxation of previous purifying selection. We tested this hypothesis by sequencing the high-elevation specialist Tetramorium alpestre and four other phylogenetically related species. In support of our hypothesis, we recorded a strong shift of selective forces in T. alpestre, in particular a stronger magnitude of diversifying and relaxed selection when compared with all other ants. We further disentangled candidate molecular adaptations in both gene expression and protein-coding sequence that were identified by our genome-wide analyses. In particular, we demonstrate that T. alpestre has 1) a higher level of expression for stv and other heat-shock proteins in chill-shock tests and 2) enzymatic enhancement of Hex-T1, a rate-limiting regulatory enzyme that controls the entry of glucose into the glycolytic pathway. Together, our analyses highlight the adaptive molecular changes that support colonization of high-altitude environments.
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Affiliation(s)
| | - Patrick Krapf
- Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Ilda D'Annessa
- Istituto di Scienze e Tecnologie Chimiche "Giulio Natta", CNR (SCITEC-CNR), Milan, Italy
| | - Alexander Gamisch
- Department of Ecology, University of Innsbruck, Innsbruck, Austria.,Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Herbert C Wagner
- Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Andrew D Nguyen
- Department of Entomology and Nematology, University of Florida, Gainesville, FL
| | - Evan P Economo
- Biodiversity & Biocomplexity Unit, Okinawa Institute of Science & Technology, Onna, Japan
| | - Alexander S Mikheyev
- Ecology and Evolution Unit, Okinawa Institute of Science & Technology, Onna, Japan
| | - Benoit Guénard
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Reingard Grabherr
- Institute of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Philipp Andesner
- Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | | | - Daniele Di Marino
- Department of Life and Environmental Sciences - New York-Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, Ancona, Italy
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Hsu HW, Chiu MC, Lee CC, Lee CY, Yang CCS. The Association between Virus Prevalence and Intercolonial Aggression Levels in the Yellow Crazy Ant, Anoplolepis Gracilipes (Jerdon). INSECTS 2019; 10:insects10120436. [PMID: 31817209 PMCID: PMC6956197 DOI: 10.3390/insects10120436] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/29/2019] [Accepted: 11/30/2019] [Indexed: 01/30/2023]
Abstract
The recent discovery of multiple viruses in ants, along with the widespread infection of their hosts across geographic ranges, provides an excellent opportunity to test whether viral prevalence in the field is associated with the complexity of social interactions in the ant population. In this study, we examined whether the association exists between the field prevalence of a virus and the intercolonial aggression of its ant host, using the yellow crazy ant (Anoplolepis gracilipes) and its natural viral pathogen (TR44839 virus) as a model system. We delimitated the colony boundary and composition of A. gracilipes in a total of 12 study sites in Japan (Okinawa), Taiwan, and Malaysia (Penang), through intercolonial aggression assay. The spatial distribution and prevalence level of the virus was then mapped for each site. The virus occurred at a high prevalence in the surveyed colonies of Okinawa and Taiwan (100% infection rate across all sites), whereas virus prevalence was variable (30%–100%) or none (0%) at the sites in Penang. Coincidentally, colonies in Okinawa and Taiwan displayed a weak intercolonial boundary, as aggression between colonies is generally low or moderate. Contrastingly, sites in Penang were found to harbor a high proportion of mutually aggressive colonies, a pattern potentially indicative of complex colony composition. Our statistical analyses further confirmed the observed correlation, implying that intercolonial interactions likely contribute as one of the effective facilitators of/barriers to virus prevalence in the field population of this ant species.
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Affiliation(s)
- Hung-Wei Hsu
- Laboratory of Insect Ecology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan;
| | - Ming-Chung Chiu
- Department of Biology, Graduate School of Science, Kobe University, Kobe 657-8501, Japan;
| | - Ching-Chen Lee
- Center for Ecology and Environment, Department of Life Science, Tunghai University, Taichung 40704, Taiwan;
| | - Chow-Yang Lee
- Department of Entomology, University of California, Riverside, 900 University Avenue, Riverside, CA 92521, USA;
| | - Chin-Cheng Scotty Yang
- Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
- Correspondence: ; Tel.: +81-70-4144-2823
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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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