Fighting Ability Research Articles

Game theory elucidates how competitive dynamics mediate animal social networks

BackgroundWhile most game theoretical models assume that individuals randomly interact with all other group members, strong evidence indicates that individuals tend to preferentially interact with some of them. The position of an individual in a network affects, among other factors related to survival, its predation risk and competitive success. Here I then modified the Hawk-Dove game to explore the effect of social network structure on competitive strategy of individuals that differ in their fighting ability and may adjust their use of the Hawk, Dove and Assessor tactics to maximize their foraging success when they meet opponents they are connected with.ResultsFrom randomly generated networks, I demonstrate that phenotypic assortment by fighting ability reduces individuals’ aggressiveness and, as such, favours cooperative interactions. Furthermore, the success of individuals with the weakest fighting ability is usually highest within networks where they most frequently meet opponents with the same fighting ability as their own, suggesting they might benefit from breaking connections with strong contestants. This might be the case when strong contestants systematically rely on the aggressive Hawk tactic or the risk of being predated is low and independent of the number of neighbours. Thus, I extended the model and built a dynamic model to allow individuals not only to adjust their behaviour to local conditions but also to modify the structure of the social network. The number of connections and degree of phenotypic assortment are then affected by ecological factors (e.g. resources value and predation risk), but above all by whether individuals can reliably assess the competitive ability of their opponents and adjust their behaviour accordingly.ConclusionsThese findings provide strong evidence that behaviour can play a key role in shaping network structure and highlight the importance of considering the coevolution of network and behaviour to apprehend its consequences on population dynamics.

Sexually selected weapons can wear out, decreasing their effectiveness in combat.

Sexual selection has resulted in some of the most elaborate traits seen in animals, many of which are used as weapons. These weapons can be incredibly diverse, even within species. Such morphological variation has largely been attributed to the environment in which individuals are reared and their genetics. However, variation in weapon form could also be the result of a weapon wearing out from usage. This mechanism has received relatively little attention. In this study, we demonstrate that sexually selected weapons can wear out from repeated use, providing experimental evidence that weapon usage can contribute to the diversity of weapon shapes observed within species. In a second experiment, we demonstrate that having a worn-out weapon decreases an individual's fighting ability. This finding illustrates that the shape of a weapon can have an important role in determining contest outcomes. Overall, these results suggest that individuals are limited in the number of times they can effectively use their weapons, which may be one factor (among others) influencing how frequently an animal engages in a fight.

Weak males do not work hard: Reproductive investment of deficient male fiddler crabs, Austruca lactea

Abstract In iteroparous animals, it may be adaptive to adjust the amount of reproductive investment based on their current competitive ability. Male fiddler crabs use an enlarged major claw for claw-waving display in the breeding season. Males sometimes lose their claws, but they can regenerate a claw, which is an inferior weapon for male-male fights. Here, we compared the waving frequency between males with a regenerated claw (regenerated males) and with an original claw (original males) to examine the differences in the amount of reproductive investment. Regenerated males showed lower waving frequency than original males, but some regenerate males waved frequently before the optimal mating season where original males waved frequently. These results indicate that individuals with poor fighting ability that have lower chance of acquiring females invested less in waving, and may also have shifted their peak of mating period in order to avoid competition with original males.

Evolutionarily stable payoff matrix in hawk–dove games

BackgroundClassical matrix game models aim to find the endpoint of behavioural evolution for a set of fixed possible interaction outcomes. Here, we introduce an evolutionary model in which not only the players’ strategies but also the payoff matrix evolves according to natural selection.ResultsWe start out from the hawk–dove matrix game and, in a way that is consistent with the monomorphic model setup of Maynard Smith and Price, introduce an evolving phenotypic trait that quantifies fighting ability and determines the probability of winning and the cost of losing escalated hawk–hawk fights. We define evolutionarily stable phenotypes as consisting of an evolutionarily stable strategy and an evolutionarily stable trait, which in turn describes a corresponding evolutionarily stable payoff matrix.ConclusionsWe find that the maximal possible cost of escalating fights remains constant during evolution assuming a separation in the time scales of fast behavioural and slow trait selection, despite the fact that the final evolutionarily stable phenotype maximizes the payoff of hawk–hawk fights. Our results mirror the dual nature of Darwinian evolution whereby the criteria of evolutionary success, as well as the successful phenotypes themselves, are a product of natural selection.

Does losing reduce the tendency to engage with rivals to reach mates? An experimental test.

Male-male contests for access to females or breeding resources are critical in determining male reproductive success. Larger males and those with more effective weaponry are more likely to win fights. However, even after controlling for such predictors of fighting ability, studies have reported a winner-loser effect: previous winners are more likely to win subsequent contests, while losers often suffer repeated defeats. While the effect of winning-losing is well-documented for the outcome of future fights, its effect on other behaviors (e.g. mating) remains poorly investigated. Here, we test whether a winning versus losing experience influenced subsequent behaviors of male mosquitofish (Gambusia holbrooki) toward rivals and potential mates. We housed focal males with either a smaller or larger opponent for 24 h to manipulate their fighting experience to become winners or losers, respectively. The focal males then underwent tests that required them to enter and swim through a narrow corridor to reach females, bypassing a cylinder that contained either a larger rival male (competitive scenario), a juvenile or was empty (non-competitive scenarios). The tests were repeated after 1 wk. Winners were more likely to leave the start area and to reach the females, but only when a larger rival was presented, indicating higher levels of risk-taking behavior in aggressive interactions. This winner-loser effect persisted for at least 1 wk. We suggest that male mosquitofish adjust their assessment of their own and/or their rival's fighting ability following contests in ways whose detection by researchers depends on the social context.

The evolution of honest and dishonest signals of fighting ability.

Competition over resources is often decided via aggressive interactions, which may or may not escalate to all-out fights. Weapons and body size play important roles in such interactions, as they often provide reliable cues of an individual's fighting ability. In contrast, traits like nonfunctional display "weapons" may dishonestly exaggerate fighting ability in order to intimidate opponents into retreating. Signals used in the context of aggressive interactions potentially evolve via very different mechanisms than courtship signals, but have received far less theoretical attention. Here, we contrast the evolution of honest and dishonest signals of fighting ability using a game-theoretic model. Contests are assumed to consist of three discrete stages: display from a distance, low-intensity physical contact, and fighting. At each stage, contestants evaluate the fighting ability of their opponents in comparison to their own based on body size and an aggressive signal. After making this evaluation, contestants decide whether to escalate the interaction or cede to their opponent. Our model predicts that both honest and dishonest aggressive signals can exaggerate far beyond their ecological optima, but that exaggeration is more pronounced for honest signals. Equilibrium levels of aggressiveness-as measured by individuals' propensity to escalate aggressive interactions to the next stage-are independent of the honesty of signals. We additionally develop a novel approach, based on causal inference theory, to understand how changes in underlying parameters shape the coevolution of multiple traits. We use this approach to study how aggression coevolves with body and signal size in response to changes in the cost of losing a fight.

Choosing a bigger opponent: the path to victory and greater gains for the small contestant

Animals often engage in contests over limited resources. The probability of winning a contest is primarily determined by the individual's fighting ability relative to its opponent and the perceived value of the disputed resource. Individuals of the hermit crab Calcinus californiensis frequently fight over gastropod shells. We conducted a free-choice experiment to assess the factors that determine individuals’ choice of opponent, contest initiation, and contest resolution. We placed hermit crabs occupying two shell species into a large container and monitored agonistic interactions between crabs. We assessed the asymmetries in fighting ability based on the differences in body mass between the opponents. The shell species and fit (i.e., shell size relative to crab body size) were used as measures of the objective and subjective resource value, respectively. Motivation influenced contest initiation; the crabs occupying too-tight shells were more likely to initiate a contest than the ones in looser-fitting shells. In most cases, the attackers fought for a shell with a looser fit, even if that meant losing a tighter-fitting shell of the preferred shell species. The fighting success for attackers was positively associated with the number of bouts of rapping and the shell size improvement. However, success was negatively correlated with body size asymmetry; attackers that chose opponents larger than themselves were more likely to evict their opponent than the attackers that chose opponents that were smaller. Experimental designs that allow animals to select their own opponents, rather than assigning specific opponents, can strongly contribute to knowledge of agonistic interactions.Significance statementFighting dynamics are commonly assessed by estimating the influence of the resource-holding potential and resource value in pair-matched opponents. Here, however, we examined the influence of asymmetries in resource-holding potential and the objective and subjective value of gastropod shells on the choice of a contender and contest resolution through a free-choice opponent experiment in hermit crabs. The contest initiation was driven by the motivation to obtain a better gastropod shell species or one with a better size fit—factors which are known to improve individual fitness. Furthermore, fighting success was associated with an individual's persistence in displaying aggressive behaviors and its motivation to obtain a better resource. However, contrary to the predictions of game theoretical models, fighting success was higher when attackers chose opponents larger than themselves. Our results highlight the relevance of assessing fighting under more natural conditions by allowing animals to select their opponents.

Reproductive season-based plasticity in the size and strength of female crayfish (Faxonius obscurus) claws.

Animal weapons are morphological traits that improve the fighting ability of the wielder and are associated with competition. These traits are typically sexually dimorphic, with males possessing weaponry and females lacking weaponry. However, in some cases, like in many crustaceans, both males and females wield enlarged claws, which may function as weapons. Further, animal weapons may vary in their size, shape, and performance, with theory predicting that selection pressure for weaponry should be the highest when the importance of fights is the greatest, such as during a reproductive season. However, the degree and direction of selection may vary based on sex and season, with females potentially benefiting from wielding larger weapons during nonreproductive seasons. Crayfishes offer an ideal system to investigate how weapon phenotypes change across reproductive seasons since both males and females undergo a form alteration associated with reproduction. Thus, we investigated whether female Allegheny crayfish, Faxonius obscurus, claws change in size, shape, or pinching strength based on whether a female is in a reproductive or nonreproductive form. We found that female F. obscurus claws are larger and stronger during the reproductive season. These findings align with previous research on males of the same species. We discuss how predictions about the relationship between seasonality and weapon investment may differ based on sex.

Age-dependent winner-loser effects in a mangrove rivulus fish, Kryptolebias marmoratus.

The outcomes of recent fights can provide individuals information about their relative fighting ability and affect their contest decisions (winner-loser effects). Most studies investigate the presence/absence of the effects in populations/species, but here we examine how they vary between individuals of a species in response to age-dependent growth rate. Many animals' fighting ability is highly dependent on body size, so rapid growth makes information from previous fights unreliable. Furthermore, fast-growing individuals are often at earlier developmental stages and are relatively smaller and weaker than most other individuals but are growing larger and stronger quickly. We therefore predicted winner-loser effects to be less detectable in individuals with high than low growth rates and to decay more quickly. Fast-growing individuals should also display stronger winner than loser effects, because a victory when small indicates a strength which will grow, whereas a loss might soon become irrelevant. We tested these predictions using naïve individuals of a mangrove killifish, Kryptolebias marmoratus, in different growth stages. Measures of contest intensity revealed winner/loser effects only for slow-growth individuals. Both fast- and slow-growth fish with a winning experience won more of the subsequent non-escalated contests than those with a losing experience; in fast-growth individuals this effect disappeared in 3days, but in slow-growth fish it did not. Fast-growth individuals also displayed winner effects but not loser effects. The fish therefore responded to their contest experiences in a way which reflected value of the information from these experiences to them, consistent with our predictions.

How does the timing of weapon loss influence reproductive traits and trade-offs in the insect Narnia femorata?

A longstanding goal of evolutionary biology is to understand among-individual variation in resource allocation decisions and the timing of these decisions. Recent studies have shown that investment in elaborate and costly weapons can result in trade-offs with investment in testes. In this study, we ask the following questions: At what point plasticity in resource allocation to these different structures ceases during development, if at all? Furthermore, can individuals tailor their reproductive behavior to accompany structural changes? We experimentally addressed these questions in the insect Narnia femorata, quantifying resource reallocation across development for the first time, using a phenotypic engineering approach. To investigate whether allocation plasticity diminishes throughout ontogeny, we induced weapon loss at a range of different developmental stages and examined subsequent testes mass and reproductive behavior. We found that relative testes mass increased as weapon investment decreased, implying a direct trade-off between testes and weapon investment. However, autotomy postadulthood ceased to induce larger testes mass. Intriguingly, losing a weapon while young was associated with extended adult mating duration, potentially enabling compensation for reduced fighting ability. Our results highlight the importance of examining the ontogeny of trade-offs between reproductive traits and the flexibility of the relationship between reproductive morphology and behavior.

Quantitative genetics of breeding coloration in sand lizards; genic capture unlikely to maintain additive genetic variance

Sexual selection on fitness-determining traits should theoretically erode genetic variance and lead to low heritability. However, many sexually selected traits maintain significant phenotypic and additive genetic variance, with explanations for this “lek paradox” including genic capture due to condition-dependence, and breaks on directional selection due to environmental sources of variance including maternal effects. Here we investigate genetic and environmental sources of variance in the intrasexually selected green badge of the sand lizard (Lacerta agilis). The badge functions as a cue to male fighting ability in this species, and male–male interactions determine mate acquisition. Using animal models on a pedigree including three generations of males measured over an extensive 9-year field study, we partition phenotypic variance in both badge size and body condition into additive genetic, maternal, and permanent environmental effects experienced by an individual over its lifespan. Heritability of badge size was 0.33 with a significant estimate of underlying additive genetic variance. Body condition was strongly environmentally determined in this species and did not show either significant additive genetic variance or heritability. Neither badge size nor body condition was responsive to maternal effects. We propose that the lack of additive genetic variance and heritability of body condition makes it unlikely that genic capture mechanisms maintain additive genetic variance for badge size. That said, genic capture was originally proposed for male traits under female choice, not agonistic selection. If developmental pathways generating variance in body condition, and/or the covarying secondary sex trait, differ between inter- and intrasexual selection, or the rate at which their additive genetic variance or covariance is depleted, future work may show whether genic capture is largely restricted to intersexual selection processes.

Iridescent scales signal male fighting ability to access females in the jewelled splitfin Xenotoca variata.

Jewelled splitfin males (Xenotoca variata) possess multi-colour iridescent scales (speckles) on the flanks. This study tested the hypothesis that the number of speckles could be a good proxy for predicting fighting ability in contests for access to females. The experiments consisted in observing and recording males' agonistic behaviour, courtship displays and mating attempts in mixed-sex groups. The data were analysed and presented based on a Bayesian approach, which revealed that the density (cm-2 ) of speckles was positively correlated with the increase observed in the proportional frequency of attacks. Similarly, the density of speckles was positively associated with the increase observed in the frequency of courtship behaviour and with the frequency of mating attempts. Male-male aggressions drastically diminished (by eightfold) when females were removed from the observation tanks. These results indicate that the number of speckles is a consistent predictor of successful access to females and therefore, speckled males are likely to be able to gain more mating opportunities. This finding highlights the ubiquitous role iridescent colours play in visual signalling.

Զինծառայողների հոգևոր դաստիարակության կարևորությունը / The importance of spiritual education of military personnel

Spiritual element is a necessary component in the education of the military personnel. Without spirituality, it is difficult to educate a person in the qualities of self-sacrifice, discipline, sense of responsibility and honor, which are necessary for the defender of the Motherland. The Army not only teaches a military profession and creates physical fitness, but also educates high spiritual and moral qualities based on patriotism, which is impossible without the participation of the Holy Church. Realizing the importance of spiritual education of servicemen in the Armenian Army, the spiritual leadership or military chaplaincy of the Armed Forces of the Republic of Armenia was established in 1997. Its mission is to teach soldiers Holy Bible and tenets of Christian faith, according to the creed of the Armenian Apostolic Holy Church, as well as to educate them with Christian moral principles and patriotic spirit of selfless service to the interests of the state and nation. Faith helps a person to maintain discipline, to overcome fears and call of the self-preservation instinct in case of danger, and first of all during military actions. Certainly, spiritual, moral and ideological education among military personnel automatically raises the level of discipline, psychological stability, morale, conscious fulfillment of one’s duty of the Motherland Defender, their fighting ability and professionalism.

Fighting ability, personality and melanin signalling in free-living Eurasian tree sparrows (Passer montanus).

BackgroundIndividuals’ access to resources is often decided during dyadic contests the outcome of which is determined by the fighting (or competitive) ability of the participants. Individuals’ fighting ability (termed also as resource-holding power or potential, RHP) is usually associated with individual features (e.g., sex, age, body size) and is also frequently signalled through various ornaments like the black throat patch (bib) in many birds. Individual personality is a behavioural attribute often linked to fighting ability as well. Based on earlier studies, however, the relationship between personality and fighting ability is far from being straightforward. While accounting for sex and body size, we studied whether exploratory behaviour, an aspect of personality, predicts fighting ability when competing for food during winter in free-living Eurasian tree sparrows (Passer montanus). We also investigated whether the bib can serve as a potential indicator of individual competitiveness in this species.MethodsWe captured adult tree sparrows, marked them with a unique combination of colour rings, and collected data about the individuals’ sex, body size, bib size and exploratory behaviour. Birds were then released and the agonistic behaviour of the marked individuals was recorded while foraging in groups on bird feeding platforms.ResultsThe probability of winning a fight, a proxy for fighting ability of individuals, was not related to exploratory behaviour, in either of the sexes. However, bib size was positively related to probability of winning in females, but not in males. Body size was not associated with probability of winning neither in males, nor in females.ConclusionsOur results suggest that, at least in tree sparrows, the outcome of dyadic encounters over food during the non-breeding period are not determined by the exploratory personality of individuals. However, our findings provide further support for a status signalling role of the black bib in tree sparrows, and hint for the first time that bib size might function as a status signal in females as well. Finally, our results do not confirm that body size could serve as an indicator of fighting ability (i.e., RHP) in this species.

Is facial structure an honest cue to real-world dominance and fighting ability in men? A pre-registered direct replication of

Masculine facial morphology (e.g., larger jaw, prominent cheekbones) have been linked to a suite of social outcomes—including greater wealth, career progress, romantic desirability, and even greater political success. A leading explanation for these links is that dominant facial structures represent honest cues of physical dominance and fighting ability. Třebický et al. (2013) published the first study to demonstrate that masculine facial cues (e.g., large nose, deep-set eyes) similarly predict both dominance judgments and real-world fighting success, but no studies have replicated these popular findings that a large and specific assortment of masculine facial structures are implicated in both fighting ability and dominance perception. Thus, we conducted a pre-registered direct replication and extension of Třebický et al. (2013). Two separate samples of United States MTurk participants rated 516 UFC fighters' facial photographs on perceived aggressiveness (N = 500) and fighting ability (N = 500). Results showed that perceived aggressiveness was associated with masculine facial morphology (e.g., large nose, deep-set eyes) independent of bodily size. There was also some evidence that perceived fighting ability was associated with masculine facial morphology, which disappeared after controlling for bodily size. There was no support for the relation between facial structure and fighting success, and there were often negative relations between perceived aggressiveness and fighting ability on fighting success (i.e., more successful fighters were perceived as less successful and aggressive). We argue that our evolved psychology differentially processes the distinct avenues to victory that constitute overall fighting success (e.g., knockout versus submission wins).

The implicit rules of combat reflect the evolved function of combat: An evolutionary-psychological analysis of fairness and honor in human aggression

Aggression was a powerful selection pressure for our human ancestors. Aggressive contests would have selected not only for anatomical features (e.g., superior upper-body strength in adult males), but also for behavior-regulation adaptations for the conditional and cost-effective deployment of aggression. Here, we explore two concepts that appear to be part of the neurocognitive suite that regulates aggression. The first is the concept of a “fair fight”, which tags whether an aggressive bout can provide an unbiased estimate of the relative fighting ability of the combatants. The second concept is the “honorability” of a fighter, which tags whether an individual can be trusted to not inflict aggression in excess of what is needed to establish the relative fighting ability of the combatants. Eight predictions were derived from these hypotheses and tested experimentally with vignettes that varied relevant aspects of a fight. The results support the predictions. Fights are perceived as “fair” to the extent that the fighters avoid biased tactics that improve their probability of winning absent superior fighting ability (e.g., not attacking when the opponent is unprepared). Further, fighters are perceived as “honorable” when they minimize the danger to both combatants (e.g., not attacking after the opponent surrenders). We conclude by listing additional implications of the theory.

A reziliens működés kompetenciáinak fejlesztési lehetőségei a hivatásgondozó – szupervíziós – munkában segítőknél, különösen a lelkipásztori hivatásban

"Opportunities for the Development of the Competences of Resilient Operation in the Professional Care – Supervision Work – of Helpers, Especially in the Pastoral Vocation. Within the framework of this study, I present the specific resilience-enhancing role and characteristics of helpers, of a professional life path, professional caregivers, and supervising work with special focus on pastoral work, and helper vocation. I examine how the pastoral vocation picture finds its place in the family of helping vocations, how it can be defined in the search for identification, how therapy, education, how professional care appear in almost every aspect of pastoral work, and how vocation care and super success can be adapted in pastoral work. In each chapter, my reflection covers the most important resilience issues, identity issues, the person-centered approach and related concepts. I examine the relationships and methodology of resilience and supervision within the framework of helping occupations in the process of becoming a child, and I discuss how learning appears in the course of professional care along the lines of the ministry. The development of resilient competences in professional care has become important since the regime change, especially in the pastoral profession and in the intertwining of cooperation with assisting professions. Regarding the dialogue, purity and authentic presence of helper vocations and roles, the transparency and pastoral psychological approach of contexts and systems is an increasingly topical direction and issue. Main question: Is there sufficient insight and awareness to examine the respective helping vocations, the pastor's professional life path, his tired or burnt-out personality in the ministry, and his important fighting ability in the midst of crises? Are we looking for preventive ways? Is today’s pastor motivated enough to pay attention to his psychical, spiritual, physical, and social health? If so, how can these be achieved? As a researcher, as an active psychotherapist working with couples and families, as a professional/supervisor, pastor wife, active Christian pastoral and mental health professional, and a pastoral psychologist, I think in several dimensions and systemic perspectives. As a helper, professional care-giver/supervisor, the issue of identity is important. I see spirituality as a kind of “driver” in the process, and I think it is decisive – it can be inspiring, but it can also be disincentive. Calibration is the task of the authentic helper of the time. That is, continuous reflection and self-reflection in a spiritual dimension. The goal is to mature, to fight/cope resiliently. The freedom to jump, the intuitive way, the path of development and learning are puzzle pieces of the spiritual dimension, a space for coping and fulfilment. Knowing God, I know myself, and knowing myself (in humility) brings me closer to God. Keywords: identity, professional identity, professional image of helpers and pastors, motivation, authenticity, empathy, IQ/EQ/SQ (intellect/emotion/spirituality – intelligence), focus, resilience, learning, stress, coping, professional care/supervision "

Relationships among Behavior, Chromatism, and Morphology in Male Aggressive Encounters in Tropidurus spinulosus

Male–male aggressive encounters in lizards may involve physical confrontation or the use of multiple cues to signal fighting ability. Behavioral, chromatic, and morphological traits may be associated to reinforce gradual messages to escalate or deescalate interactions during encounters. Our first aim was to provide a detailed ethogram of male–male aggressive encounters in the social lizard Tropidurus spinulosus. Then, we aimed to elucidate the association among behaviors and morphological and chromatic characters. Our results showed several behavioral displays organized in sequential phases, with two displays being characteristic of this species; furthermore, increasingly threatening displays may be repeated several times before reaching physical aggression. Males that dominated the encounters usually had more extended color bands in the most visible body parts, lower body condition, and preferentially had performed pushup early in the bout, whereas males that were ultimately chased had high color band extension in the chest and high testicular volume and performed more lateral compression and head-swipe escalating readily to physical aggression by biting the opponent. In conclusion, the behavioral displays employed by different males were associated with their morphological and chromatic characters, highlighting the existence of signaling strategies among individuals.

Drivers and outcomes of between-group conflict in vervet monkeys.

Neighbouring groups compete over access to resources and territories in between-group encounters, which can escalate into between-group conflicts (BGCs). Both the ecological characteristics of a territory and the rival's fighting ability shape the occurrence and outcome of such contests. What remains poorly understood, however, is how seasonal variability in the ecological value of a territory together with fighting ability related to the likelihood of between-group encounters and the extent to which these escalate into conflicts. To test this, we observed and followed four vervet monkey groups in the wild, and recorded the group structure (i.e. size, composition), the locations and the outcomes of 515 BGCs. We then assessed key ecological measures at these locations, such as vegetation availability (estimated from Copernicus Sentinel 2 satellite images) and the intensity of usage of these locations. We tested to what extent these factors together influenced the occurrence and outcomes of BGCs. We found that the occurrence of BGCs increased at locations with higher vegetation availability relative to the annual vegetation availability within the group's home territory. Also, groups engaging in a BGC at locations far away from their home territory were less likely to win a BGC. Regarding group structure, we found that smaller groups systematically won BGCs against larger groups, which can be explained by potentially higher rates of individual free-riding occurring in larger groups. This study sheds light on how the ecology of encounter locations in combination with a group's social characteristics can critically impact the dynamics of BGCs in a non-human primate species.This article is part of the theme issue ‘Intergroup conflict across taxa’.

Flashy male Jamaican anoles Anolis grahami show accelerated telomere attrition

Secondary sexual traits have evolved through sexual selection, many species have developed signals that can indicate their level of other fitness-relevant traits such as fight ability. Previous studies have shown that male sexual signals are honest signals about quality in an intrasexual context, demonstrating a direct relationship between the signal’s design and the fighting ability of its possessor. However, signals can be costly since conspicuous signals are more likely to attract predators or be energetically expensive. Here we have analysed if dewlap size and colouration were reliable signs of a male’s bite force, and the physiological costs associated with larger dewlaps and intense colouration in Jamaican anoles (Anolis grahami). We analysed dewlap size and colouration against bite force, and telomere attrition. Our results supported the hypothesis that dewlap size and colour intensity are honest predictors of an individual’s fighting potential as indicated by bite force. However, we have also found a relationship between colour intensity with higher telomere attrition rates, thereby indicating a possible cost of this trait for the individual.