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Social species rely on acquiring appropriate social skills to navigate their social environment. Developmental plasticity allows individuals to develop an appropriate phenotype by receiving cues from their social and nonsocial environment. However, committing to a specific phenotype early in life may prove maladaptive if there is a mismatch between the early and future environment. To address potential mismatches, multiple or extended sensitive periods provide opportunities for individuals to gather the necessary information in changing and predictable environments. Cooperative breeders, like the highly social cichlid Neolamprologus pulcher , typically experience changing environments especially during dispersal. While we know that early development is critical for the acquisition of social competence, it remains uncertain whether a second or extended sensitive period exists around the time of dispersal decisions in cooperative breeders. Here we manipulated the early and late life social environment of N. pulcher and asked whether individuals retain plasticity to adjust their social phenotype around sexual maturation. Juveniles were raised for 2 months with or without adults and tested for social competence. Shortly before reaching sexual maturity, they were randomly assigned to be housed alone, with siblings or with a social group for an additional 2 months before undergoing further social competence testing. Aggressive and submissive behaviours were assessed in two social contexts. Fish raised with a large group exhibited greater social competence compared to those raised only among siblings, regardless of subsequent social experiences. This suggests that either early life cues reliably predict future environments in nature or that constraints on late life plasticity exist. • We study the acquisition of social competence in cooperatively breeding fish. • We investigate whether sensitive periods exist early and late in life. • Early development is critical in acquiring social competence in Neolamprologus pulcher. • Later development does not influence the social competence in N. pulcher. [ABSTRACT FROM AUTHOR]

In cooperatively breeding species, subordinates can obtain group membership through social interactions with other group members or by providing services such as helping with territory defence. Large subordinate individuals, which can reproduce, are expected to adjust their behaviour as a function of the demand of help and group size because if the environmental conditions allow, they may either leave the group to start breeding or queue for the breeding position in their natal group. The number of helpers in a group is expected to affect the need of help by dominants and consequently also the level of subordination shown by helpers. In a series of field experiments, we manipulated the need of help and the opportunities for subordinates to show submissive behaviour in a wild population of the cooperatively breeding species Neolamprologus pulcher. We assessed if group size determines the social behavioural strategy of large subordinate individuals. When experimentally eliciting submissive behaviour, large subordinates from small groups showed a lower frequency of submissive behaviour compared to large groups; moreover, they tended to show a higher frequency of sand digging than in large groups. In contrast, neither territory defence in the presence of a heterospecific egg and larvae predator nor dispersal propensity, measured as prospecting frequency in neighbouring territories, was affected by group size. A principal component analysis revealed that prospecting is uncorrelated with submissive behaviour and helping behaviour. Our results suggest that group size may be involved in shaping behavioural phenotypes of juvenile subordinates. [ABSTRACT FROM AUTHOR]

The ability to flexibly adjust behaviour to social and non-social challenges is important for successfully navigating variable environments. Social competence, i.e. adaptive behavioural flexibility in the social domain, allows individuals to optimize their expression of social behaviour. Behavioural flexibility outside the social domain aids in coping with ecological challenges. However, it is unknown if social and non-social behavioural flexibility share common underlying cognitive mechanisms. Support for such shared mechanism would be provided if the same neural mechanisms in the brain affected social and non-social behavioural flexibility similarly. We used individuals of the cooperatively breeding fish Neolamprologus pulcher that had undergone early-life programming of the hypothalamic–pituitary–interrenal axis by exposure to (i) cortisol, (ii) the glucocorticoid receptor antagonist mifepristone, or (iii) control treatments, and where effects of stress-axis programming on social flexibility occurred. One year after the treatments, adults learned a colour discrimination task and subsequently, a reversal-learning task testing for behavioural flexibility. Early-life mifepristone treatment marginally enhanced learning performance, whereas cortisol treatment significantly reduced behavioural flexibility. Thus, early-life cortisol treatment reduced both social and non-social behavioural flexibility, suggesting a shared cognitive basis of behavioural flexibility. Further our findings imply that early-life stress programming affects the ability of organisms to flexibly cope with environmental stressors. [ABSTRACT FROM AUTHOR]

Use of virtual proxies of live animals are rapidly gaining ground in studies of animal behaviour. Such proxies help to reduce the number of live experimental animals needed to stimulate the behaviour of experimental individuals and to increase standardisation. However, using too simplistic proxies may fail to induce a desired effect and/or lead to quick habituation. For instance, in a predation context, prey often employ multimodal cues to detect predators or use specific aspects of predator behaviour to assess threat. In a live interaction, predator and prey often show behaviours directed towards each other, which are absent in virtual proxies. Here we compared the effectiveness of chemical and visual predator cues in the cooperatively breeding cichlid Neolamprologus pulcher, a species in which predation pressure has been the evolutionary driver of its sociality. We created playbacks of predators simulating an attack and tested their effectiveness in comparison to a playback showing regular activity and to a live predator. We further compared the effectiveness of predator odour and conspecific skin extracts on behaviours directed towards a predator playback. Regular playbacks of calmly swimming predators were less effective than live predators in stimulating a focal individual's aggression and attention. However, playbacks mimicking an attacking predator induced responses much like a live predator. Chemical cues did not affect predator directed behaviour. [ABSTRACT FROM AUTHOR]

The ability to respond flexibly to environmental challenges, for instance by learning or by responding appropriately to novel stimuli, may be crucial for survival and reproductive success. Experiences made during early ontogeny can shape the degree of behavioural flexibility maintained by individuals during later life. In natural habitats, animals are exposed to a multitude of social and non-social ecological factors during early ontogeny, but their relative influences on future learning ability and behavioural flexibility are only poorly understood. In the cooperatively breeding cichlid Neolamprologus pulcher, we investigated whether early social and predator experiences shape the learning performance, flexibility, and response to novelty of adults. Fish were reared either with or without parents and helpers and with or without perceived predation risk in a full-factorial experiment. We investigated the influence of these treatments on learning performance and flexibility in a spatial acquisition and reversal learning task. To test for response to novelty, we performed a neophobia test. We found that fish reared with predator experience, but without the presence of older group members outperformed fish with other rearing backgrounds in reversal learning and that individuals, which had been reared in a socially more complex environment together with older group members responded less neophobic toward a novel object than individuals reared among siblings only. Comparative evidence from fish and rats suggests that these developmental effects may be driven by the cues of safety perceived in the presence of guarding parents. [ABSTRACT FROM AUTHOR]

Social competence is defined as the ability of an animal to optimize the expression of social behaviour as a function of the available social information. The social environment encountered early in life can affect the expression of various social behaviours later in life. We investigated whether early social experience can affect social competence. In the cooperatively breeding cichlid Neolamprologus pulcher, we tested whether individuals reared with older brood-caring conspecifics persistently perform better in a series of tasks (1) simulating different social contexts, (2) assigning individuals different social roles and (3) exposing them to an unknown social situation. Fish that had been reared together with older conspecifics showed more appropriate behaviours both as winners (more aggressive displays) and as losers (more submissive displays) when aggressively competing with peers over a resource, and when trying to be accepted as subordinate group member and prospective brood care helper by an unfamiliar dominant pair (more submissive displays near shelters), a situation they had never encountered before. In both tasks fish that had grown up with older fish were tolerated better by conspecifics than fish reared with same-age siblings only. We detected effects of the early environment on social behaviour in the juvenile and adult stages of the test fish. Our results suggest that growing up in more complex social groups fosters a general social ability (i.e. social competence) in N. pulcher that improves their performance across different social roles and contexts, and which may provide fitness benefits. [Copyright &y& Elsevier]

The early social environment can affect the social behaviour of animals throughout life. We tested whether the presence of adults during early development influences the social behaviour of juveniles later on in the cooperatively breeding cichlid Neolamprologus pulcher. In a split-brood design we raised half of the broods together with parents and with or without brood care helpers, and the other half without adults. During early rearing, fry raised with adults showed more aggressive and submissive behaviour to each other than fish raised with siblings only. After transferring the young to a neutral environment lacking adult conspecifics we tested their social performance in a competitive situation. Either young were assigned the ownership of a shelter or they had no shelter of their own. As shelter owners, fish that had been raised with adults showed more of an energetically cheaper, restrained form of aggression, while as intruders they behaved submissively more often than fish raised without adults. The strength of these treatment effects depended on the opponent''s social experience, and contests were terminated earlier only when both opponents had been raised with adults. Our results show that the social-rearing conditions persistently affect the economy and adequacy of individual reactions to social challenges, which is reminiscent of social competence effects known from humans. Remarkably, during the social treatment period brood care involved only protection but no direct interactions between adults and young. We discuss potential mechanisms by which the presence of brood-caring adults may persistently affect social skills in animals. [Copyright &y& Elsevier]

Size-assortative mating is one of the most common mating patterns in nature. Nevertheless, the underlying behavioural mechanisms have received little attention. Assortment is typically assumed to result from mate choice, which can be coupled with differences in competitive potential. We investigated the behavioural mechanisms underlying size-assortative mating in a monogamous, biparental goby cichlid, where mutual mate choice should be expected. We performed three field experiments with females and males of Eretmodus cyanostictus to test for the existence of mate preferences in general and with regard to size: (1) a sequential presentation of differently sized potential partners; (2) a removal of partners combined with surveillance until re-pairing with a new partner; and (3) the simultaneous release of new and original partners on the experimental territories. In the removal experiment, we found evidence for weak preferences for large partners relative to own size and to the original partner''s size, but pairs were formed irrespective of these preferences. The ecological importance of being paired appears to reduce choosiness and to override mate preferences. Territory ownership was quickly decided by aggressive interactions between original and new partners, and in both sexes the larger contestant won and was immediately accepted as partner by the resident. Our results suggest that strong intrasexual competition can be a powerful promoter of size-assortative mating even in the absence of active mate choice. [Copyright &y& Elsevier]

Winner and loser effects are widespread among animal taxa and are known to influence hierarchy formation, although it is unclear how rank influences such effects in species organized in social hierarchies. We investigated the existence of winner and loser effects and the effect of social rank on such effects in Neolamprologus pulcher , a cooperatively breeding cichlid fish. Social groups of these fish are organized in strict linear, size-based hierarchies. We successively assigned a dominant or subordinate rank to each of 18 focal individuals in balanced order, followed by an assigned winning or losing experience, respectively, resulting in a two-by-two factorial design. For each of the four treatment combinations, we recorded the performance of the focal fish in contests over a resource with similar-sized, naïve opponents. Assigned winners won subsequent contests more often than losers, were more likely to escalate the contest and showed more overt aggression during a contest. Moreover, individuals with assigned subordinate rank showed more restrained aggression. However, winner and loser effects were not modulated by rank. This study shows that winner–loser effects exist in a highly social fish with linear social hierarchy. Moreover, fighting experience and rank may play complementary roles in conflict resolution. • Whether social hierarchy position influences winner-loser effects is unknown. • In a fully crossed design, we manipulated current rank and winning experience. • Assigned winners showed more aggression and escalated contests more than losers. • Assigned subordinates showed more threat behaviour than dominants. • Rank and winning experience affect contests complementarily but not interactively. [ABSTRACT FROM AUTHOR]