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Balzarini V, Taborsky M, Villa F, Frommen JG. Computer animations of color markings reveal the function of visual threat signals in Neolamprologus pulcher. Curr Zool 2017; 63:45-54. [PMID: 29491962 PMCID: PMC5804153 DOI: 10.1093/cz/zow086] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 07/19/2016] [Indexed: 11/24/2022] Open
Abstract
Visual signals, including changes in coloration and color patterns, are frequently used by animals to convey information. During contests, body coloration and its changes can be used to assess an opponent's state or motivation. Communication of aggressive propensity is particularly important in group-living animals with a stable dominance hierarchy, as the outcome of aggressive interactions determines the social rank of group members. Neolamprologus pulcher is a cooperatively breeding cichlid showing frequent within-group aggression. Both sexes exhibit two vertical black stripes on the operculum that vary naturally in shape and darkness. During frontal threat displays these patterns are actively exposed to the opponent, suggesting a signaling function. To investigate the role of operculum stripes during contests we manipulated their darkness in computer animated pictures of the fish. We recorded the responses in behavior and stripe darkness of test subjects to which these animated pictures were presented. Individuals with initially darker stripes were more aggressive against the animations and showed more operculum threat displays. Operculum stripes of test subjects became darker after exposure to an animation exhibiting a pale operculum than after exposure to a dark operculum animation, highlighting the role of the darkness of this color pattern in opponent assessment. We conclude that (i) the black stripes on the operculum of N. pulcher are a reliable signal of aggression and dominance, (ii) these markings play an important role in opponent assessment, and (iii) 2D computer animations are well suited to elicit biologically meaningful short-term aggressive responses in this widely used model system of social evolution.
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Affiliation(s)
- Valentina Balzarini
- Institute of Ecology and Evolution, Behavioral Ecology Division, University of Bern, Wohlenstrasse 50a, 3032 Hinterkappelen, Switzerland
| | - Michael Taborsky
- Institute of Ecology and Evolution, Behavioral Ecology Division, University of Bern, Wohlenstrasse 50a, 3032 Hinterkappelen, Switzerland
| | - Fabienne Villa
- Institute of Ecology and Evolution, Behavioral Ecology Division, University of Bern, Wohlenstrasse 50a, 3032 Hinterkappelen, Switzerland
| | - Joachim G. Frommen
- Institute of Ecology and Evolution, Behavioral Ecology Division, University of Bern, Wohlenstrasse 50a, 3032 Hinterkappelen, Switzerland
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Acker P, Grégoire A, Rat M, Spottiswoode CN, van Dijk RE, Paquet M, Kaden JC, Pradel R, Hatchwell BJ, Covas R, Doutrelant C. Disruptive viability selection on a black plumage trait associated with dominance. J Evol Biol 2015; 28:2027-41. [PMID: 26249359 PMCID: PMC4949555 DOI: 10.1111/jeb.12717] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 07/26/2015] [Accepted: 08/01/2015] [Indexed: 11/30/2022]
Abstract
Traits used in communication, such as colour signals, are expected to have positive consequences for reproductive success, but their associations with survival are little understood. Previous studies have mainly investigated linear relationships between signals and survival, but both hump-shaped and U-shaped relationships can also be predicted, depending on the main costs involved in trait expression. Furthermore, few studies have taken the plasticity of signals into account in viability selection analyses. The relationship between signal expression and survival is of particular interest in melanin-based traits, because their main costs are still debated. Here, we first determined the main factors explaining variability in a melanin-based trait linked to dominance: the bib size of a colonial bird, the sociable weaver Philetairus socius. We then used these analyses to obtain a measure representative of the individual mean expression of bib size. Finally, we used capture-recapture models to study how survival varied in relation to bib size. Variation in bib size was strongly affected by year and moderately affected by age, body condition and colony size. In addition, individuals bearing small and large bibs had higher survival than those with intermediate bibs, and this U-shaped relationship between survival and bib size appeared to be more pronounced in some years than others. These results constitute a rare example of disruptive viability selection, and point towards the potential importance of social costs incurred by the dominance signalling function of badges of status.
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Affiliation(s)
- P Acker
- CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, Montpellier Cedex 05, France.,Laboratoire Évolution & Diversité Biologique (UMR 5174 EDB), Université Toulouse 3 Paul Sabatier - CNRS - ENFA, Toulouse, France
| | - A Grégoire
- CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, Montpellier Cedex 05, France
| | - M Rat
- Percy FitzPatrick Institute, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch, South Africa
| | - C N Spottiswoode
- Percy FitzPatrick Institute, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch, South Africa.,Department of Zoology, University of Cambridge, Cambridge, UK
| | - R E van Dijk
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - M Paquet
- CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, Montpellier Cedex 05, France.,Percy FitzPatrick Institute, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch, South Africa
| | - J C Kaden
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.,The Royal Zoological Society of Scotland, Edinburgh Zoo, Edinburgh, UK
| | - R Pradel
- CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, Montpellier Cedex 05, France
| | - B J Hatchwell
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - R Covas
- Percy FitzPatrick Institute, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch, South Africa.,CIBIO, University of Porto, Vairão, Portugal.,Biology Department, Science Faculty, University of Porto, Porto, Portugal
| | - C Doutrelant
- CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, Montpellier Cedex 05, France.,Percy FitzPatrick Institute, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch, South Africa
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