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Individual repeatability characterizes many behaviors. Repeatable behavior may result from repeated social interactions among familiar group members, owing to adaptive social niche specialization. In the context of aggression, in species like field crickets, social niche specialization should also occur when individuals repeatedly interact with unfamiliar individuals. This would require the outcome of social interactions to have carry-over effects on fighting ability and aggressiveness in subsequent interactions, leading to long-term among-individual differentiation. To test this hypothesis, we randomly assigned freshly emerged adult males of the southern field cricket Gryllus bimaculatus to either a solitary or social treatment. In social treatment, males interacted with a same-sex partner but experienced a new partner every 3 days. After 3 weeks of treatment, we repeatedly subjected treated males to dyadic interactions to measure aggression. During this time, we also continuously measured the 3-daily rate of carbohydrate and protein consumption. Individual differentiation was considerably higher among males reared in the social versus solitary environment for aggressiveness but not for nutrient intake. Simultaneously, social experience led to lower within-individual stability (i.e. increased within-individual variance) in carbohydrate intake. Past social experiences, thus, shaped both behavioral individuality and stability. While previous research has emphasized behavioral individuality resulting from repeated interactions among familiar individuals, our study implies that behavioral individuality, in the context of aggression, may generally result from social interactions, whether with familiar or unfamiliar individuals. Our findings thus imply that social interactions may have a stronger effect on individual differentiation than previously appreciated. [ABSTRACT FROM AUTHOR]

Social interactions shape relationships between individuals in complex societies. Affiliative interactions are associated with benefits and strengthen social bonds, while aggressive interactions are costly and negatively affect social bonds. Individuals may attempt to reduce aggressive encounters through submissive displays directed at higher-ranking individuals. Thus, fine-scale patterns of affiliative, aggressive, and submissive interactions may reflect costly and beneficial social relationships within groups, providing insight into the benefits of group living and the mechanisms of conflict resolution. So far, however, most studies have looked at social interactions and benefits of group living in isolation. We investigated how the strength of social bonds (affiliative vs. aggressive interactions) and submissive displays varied with kin-selected and potential mating benefits, and with reproductive conflict in the cooperatively breeding purple-crowned fairy-wren, Malurus coronatus. Our results revealed that subordinates formed equally strong social bonds with kin and potential mates (unrelated opposite-sex individuals) while they formed antagonistic relationships with reproductive competitors that offered no kin-selected or mating benefits (unrelated same-sex individuals). Submissive displays were directed exclusively at same-sex breeders, regardless of relatedness. Affiliation and submission were associated with reduced foraging time when food was limited, indicating a cost to maintaining positive relationships. Together, our results suggest that the strength of social bonds is determined by (potential) benefits obtained from group members, while submission likely serves to reduce conflict. Our findings highlight the importance of time-costly social interactions for maintaining relationships with group members, providing insight into how social groups of individuals with (partly) divergent interests can remain stable. [ABSTRACT FROM AUTHOR]

Vocal learning in birds is a complex animal behavior with several parallels to vocal learning in humans. Early experiments in the 70s showing that juvenile birds could learn their species' normal song presented only through loudspeakers led to the general notion that social interactions are unnecessary for song learning. These views were soon challenged, and after decades of research we know that different social factors influence song learning. Here, I discuss recent research that is getting us closer to understanding how. Juvenile birds in the wild are exposed to both direct and indirect interactions with singing adults, which can be relevant to different aspects of the learning process. The exposure to a potential living tutor may trigger or enhance the learning process, but direct interaction with a tutor producing the song type that is finally learned or incorporated to the repertoire is not required. Social interactions that the learner witnesses may be more important in determining which songs are included in the final repertoire of an adult bird. Further research is also required to better understand the role of interactions with females, not by providing a model song to imitate but by exhibiting responses contingent to juveniles practicing their songs. [ABSTRACT FROM AUTHOR]

Differences in male and female phenotypes are often the results of sexual selection. Over the years, a vast number of studies investigated how and why the 2 sexes differ in their physical appearance, reaching the conclusion that peculiar visual traits, signals, or ornaments usually evolve under the pressure of sexual selection to mediate intrasexual competition and mate choice. In social contexts, however, males and females can hold different roles and social interactions may depend on the individual gender. The female-dominated hymenopteran societies represent a fascinating scenario to investigate recognition and communication among individuals of different genders outside a common sexual selection framework because sterile female workers typically do not mate and are not attracted to males. Here, we used laboratory bioassays (lure presentation experiments) to evaluate the ability of Polistes dominula workers to discriminate between individuals of the 2 genders, investigating the relevance of the chemical and visual cues potentially involved in such process. Our results showed that P. dominula workers are able to discriminate between the sexes and visual cues rather than chemical ones are responsible for such discrimination. [ABSTRACT FROM AUTHOR]

Artificial light at night is an increasing threat for ecological processes. Previous work has highlighted the effects of nighttime light on individuals and on higher levels of biological organization, such as community ecology and ecosystem functioning. Here, we focus on the effects of artificial light at night on social interactions and group dynamics. We discuss 4 main ways of how light pollution is expected to alter social interactions and group dynamics. First, light at night can alter the activity patterns of individuals and this is predicted to affect the social network structure of populations, which in turn affects the transfer of information and diseases. Second, changes in activity patterns and disrupted biological rhythms are expected to reduce behavioral synchrony in social processes such as reproduction, migration, and dispersal. Third, increased light at night is expected to affect the communication between individuals; primarily, it will increase the opportunities for visual social information transfer. Last, artificial nighttime light is expected to lower social competence, with subsequent negative effects on aggressive interactions and group coordination. Throughout the article, we propose testable hypotheses and identify suitable study species, and we hope that this article inspires future research on the effects of bright nights on social interactions and group dynamics. [ABSTRACT FROM AUTHOR]

Why do animals associate with some individuals but not others? Mountain brushtail possums preferentially associate with maternal relatives at night, such as mothers and maternal siblings. This suggests that bonds between relatives may form through familiarity, before young are independent of their mothers. Female possums also associate for longer than males. This, in part, may be because these possums prefer to associate with kin, but male dispersal leads to the separation of male relatives.Kinship is a key factor that can influence the fitness benefits associated with social behaviors through the operation of kin selection. A species’ patterns of dispersal, and resulting fine-scale spatial genetic structure, can mediate kin selection by altering both the capacity for kin cooperation and the intensity of kin competition. In this study, we used proximity logger collars and multilocus genotypes to investigate how genetic relatedness influences the associations of mountain brushtail possums (Trichosurus cunninghami) in the context of fine-scale spatial genetic structure. We found distinct differences between diurnal and nocturnal associations. Diurnal (den-sharing) associations occurred within a small subset of mainly male–female dyads, whose members were socially pair-bonded. In contrast, nocturnal associations occurred between multiple individuals of both sexes. Spatial proximity was an important factor influencing the nocturnal encounter rate. Further, proximity was associated with relatedness between individuals, a pattern that was stronger among females than males. After proximity was accounted for, we found that possums who shared a mitochondrial haplotype associated more often and for longer during nocturnal activity. By comparison, autosomal nuclear relatedness metrics did not explain associations. This is likely to represent, in part, mother–offspring associations but may also indicate a general preference for associating with familiar individuals. Females also associated for longer than did males, which may be attributed to a combination of kin preference and differences between the sexes in genetic structuring. Thus, this study demonstrates the way social behaviors may be shaped by how kin selection and fine-scale spatial genetic structure interact. [ABSTRACT FROM PUBLISHER]

Competition within sexes is expected when resources are sex specific, whereas competition between sexes can occur when similar resources are exploited. Local population density and sex ratio will determine the amount of sex-specific interactions and thus the potential degree of sex-specific competition. In contrast, high densities and the density of same-sex individuals may also positively influence survival, for example, by facilitating the exploitation of resources. The population density and sex ratio may therefore differently affect survival of males and females and thus also affect the expected fitness gains of producing a certain offspring sex. In this paper, we investigate experimentally whether and how sex-specific local densities affected sex-specific annual local survival of juvenile and adult great tits. We manipulated the density and sex ratio of fledgling great tits in 12 forest plots during 3 consecutive breeding seasons and monitored local survival until the next breeding season. We found no negative effects of the number of same- or opposite-sex competitors on juvenile local survival. Instead, local survival of juveniles of both sexes increased with the density of same-sex fledglings. Adult local survival was negatively affected by an experimental increase in density of nestlings, yet associated positively with the natural breeding pair density in a plot. Juvenile local survival related negatively to breeding pair density. Our results reveal experimental evidence for both negative effects of density on adult local survival and positive sex-specific effects on juvenile local survival, which shape sex-specific fitness prospects and might thus also alter optimal sex allocation decisions. [ABSTRACT FROM PUBLISHER]

Whether male competition and female choice act in concert, independently, or in opposition is a critical issue for understanding sexual selection. In complex social systems, the outcomes of pairwise interactions may not be accurate indicators of how sexual selection emerges. We investigated how female choice and male competition interact in the bluefin killifish, Lucania goodei, in a 3-staged experiment where 1) females could choose between 2 males, 2) those males could interact in the presence of that female, and 3) females and males could freely interact and spawn. In the pairwise stages (1 and 2), females displayed pronounced preferences between males and male competition produced a distinctly dominant individual. None of the morphological traits, including color, measured in males were associated with either female preference or male dominance. When all 3 fish interacted (stage 3), male activity level was the sole predictor of spawning success. Males with elevated activity levels were more aggressive toward males and females, exhibited intensified courtship, and obtained more spawns. Female preference did not predict the number of spawns with a male, but it did predict her latency to spawn; females spawned more quickly with preferred males. Thus, male competition and female choice interact to determine reproductive success, but there is evidence for conflict and a cost to females of associating with dominant males. Reproductive success in this species is not easily predicted from simple measures of morphology or female preference and is influenced by complex social interactions, both between males, and between males and females. [ABSTRACT FROM PUBLISHER]