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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2009.12.008 Byline: Cornelia Arnold (a), Barbara Taborsky (a)(b) Abstract: 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. Author Affiliation: (a) Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Switzerland (b) Evolution & Ecology Program, IIASA, Austria Article History: Received 6 October 2009; Revised 2 November 2009; Accepted 24 November 2009 Article Note: (miscellaneous) MS. number: 09-00646

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2008.10.020 Byline: Barbara Taborsky (a)(b), Luzia Guyer (a), Michael Taborsky (a) Abstract: 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. Author Affiliation: (a) Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Switzerland (b) Evolution & Ecology Program, IIASA, Austria Article History: Received 19 May 2008; Revised 7 August 2008; Accepted 26 October 2008 Article Note: (miscellaneous) MS. number: 08-00330

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2004.03.005 Byline: Barbara Taborsky, Katharina Foerster Abstract: The protection of young from predators is an important and costly component of parental care, and this investment should be adjusted to the predation risk for the offspring. Parents are known to fine-tune defence intensity to the perceived need of protection, yet little attention has been paid to individual variation in the duration of brood defence. To optimize parental investment it may be beneficial to prolong brood care when the predation risk for the young is high. We tested whether cichlids of the species Ctenochromis horei adjust mouthbrooding duration to the perceived predation risk of their offspring. After spawning, females were transferred to an experimental tank, where they incubated the clutch either alone or in the presence of a natural predator of young. Females extended their incubation period by 4.3 days on average when the predator was present. During this prolonged incubation, young continued to grow in the female's buccal cavity. Interspawning interval was longer for females that incubated eggs than for those that did not, although incubation had no long-term negative effects on female condition or egg number or size. Incubating females may thus breed less frequently. Brood care duration should hence be considered as a flexible and potentially costly trait when investigating costs and benefits of parental care. Author Affiliation: (*) Konrad Lorenz-Institut fur Vergleichende Verhaltensforschung, Vienna, Austria (a ) Behavioural Ecology, University of Bern, Switzerland Article History: Received 18 June 2003; Revised 18 September 2003; Accepted 13 March 2004 Article Note: (miscellaneous) MS. number: 7752

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2004.03.007 Byline: Christoph Gruter, Barbara Taborsky Abstract: Biparental care is expected to occur if (1) the costs of desertion for a parent are high, because of greatly reduced survival prospects of offspring, or (2) the benefits of desertion are low. Among mouthbrooding fish, biparental care is rare because the mouth cavity provides a safe brooding site, thus reducing the selective advantages of shared brood care. Eretmodus cyanostictus is a monogamous mouthbrooding cichlid in which the entire clutch is brooded first by the female and then by the male. To test the hypothesis that females alone can produce viable young, we designed an experiment in which females were separated from their mates. Unassisted females prolonged incubation but released as many young as females assisted by males. However, they compensated only partially for male incubation and released smaller and less-developed young. This may substantially reduce offspring survival chances in the wild. The body condition of single females decreased more during incubation and they had a prolonged interspawning interval, but produced similar egg numbers and weights in the next clutch. Our results suggest that the male's brood care effort is an important cause of the maintenance of biparental care and monogamy in E. cyanostictus. Author Affiliation: Behavioural Ecology, University of Bern Article History: Received 3 July 2003; Revised 4 September 2003; Accepted 9 March 2004 Article Note: (miscellaneous) MS. number: 7779

Experiments were performed to test the hypothesis of habitat imprinting as a mechanism in European cuckoo, Cuculus canorus, for finding an appropriate host. Each of the five artificial habitats used consisted of a pair of zebra finches as a host. Results showed that hand-reared cuckoos spent significantly more time searching for their respective familiar habitats than at other habitats in 1 of 2 test years, indicating a habitat imprinting.

All organisms have a stress response system to cope with environmental threats, yet its precise form varies hugely within and across individuals, populations, and species. While the physiological mechanisms are increasingly understood, how stress responses have evolved remains elusive. Here, we show that important insights can be gained from models that incorporate physiological mechanisms within an evolutionary optimality analysis (the 'evo-mecho' approach). Our approach reveals environmental predictability and physiological constraints as key factors shaping stress response evolution, generating testable predictions about variation across species and contexts. We call for an integrated research programme combining theory, experimental evolution, and comparative analysis to advance scientific understanding of how this core physiological system has evolved. Extensive experimental and comparative studies provide a solid understanding of the physiological basis of the stress response system and its variation across and within species. However, lagging behind this is a formal theoretical framework to help unify the wealth of existing verbal hypotheses linking stress response mechanisms and fitness, and to explain how such a response system has evolved. We propose an evo-mecho approach, combining optimality models and evolutionary simulations with empirical evidence about the underlying physiology, to show how mechanistic constraints and the predictability of environmental risks shape the stress response. A deeper understanding of stress response evolution will require mechanistically informed evolutionary models, phylogenetically controlled comparative analyses, and experimental evolution studies. [ABSTRACT FROM AUTHOR]

A radiotelemetry study is conducted to observe the behavior of female common cuckoos, Cuculus canorus, in the vicinity of host nests before and during egg laying. The strong host and habitat specificity of individuals contributes to the variation in behavior between cuckoos, especially in the time of day when eggs were laid in host nests.

The preference of cuckoo females for specific habitats when searching for host nests is studied. This is confirmed as also, that host specificity also plays an important role in cuckoo females.

‘Social competence’ refers to the ability of an individual to optimise its social behaviour depending on available social information. Although such ability will enhance social interactions and thus raise Darwinian fitness, its evolutionary and ecological significance has been largely ignored. Social competence is based on behavioural flexibility. We propose that the study of social competence requires an integrative approach that aims to understand how the brain translates social information into flexible behavioural responses, how flexibility might be constrained by the developmental history of an individual or by trade-offs with other (ecological) competences, and how social plasticity feeds back on fitness. Finally we propose a hypothesis of how social competence can become a driver of social evolution. [Copyright &y& Elsevier]

• Glucocorticoid receptors (GR) are important mediators of the stress response. • GRs terminate the stress response which might improve behavioural flexibility. • While stressed, both GR blocked and control fish participated in a detour task. • Blocking GR increased fear responses and reduced behavioural flexibility. • We highlight a potential role of GR in coping with changing conditions Behavioural flexibility plays a major role in the way animals cope with novel situations, and physiological stress responses are adaptive and highly efficient mechanisms to cope with unpredictable events. Previous studies investigating the role of stress responses in mediating behavioural flexibility were mostly done in laboratory rodents using stressors and cognitive challenges unrelated to the ecology of the species. To better understand how stress mediates behavioural flexibility in a natural context, direct manipulations of the stress response and cognitive tests in ecologically relevant contexts are needed. To this aim, we pharmacologically blocked glucocorticoid receptors (GR) in adult Neolamprologus pulcher using a minimally invasive application of a GR antagonist. GR blockade prevents the recovery after a stressful event, which we predicted to impair behavioural flexibility. After the application of the GR antagonist, we repeatedly exposed fish to a predator and tested their behavioural flexibility using a detour task, i.e. fish had to find a new, longer route to the shelter when the shortest route was blocked. While the latencies to find the shelter were not different between treatments, GR blocked fish showed more failed attempts during the detour tasks than control fish. Furthermore, weak performance during the detour tasks was accompanied by an increase of fear related behaviours. This suggests that blocking GR changed the perception of fear and resulted in an impaired behavioural flexibility. Therefore, our results support a potential link between the capacity to recover from stressors and behavioural flexibility in N. pulcher with potential consequences for an effective and adaptive coping with changing environments. [ABSTRACT FROM AUTHOR]

Abstract In highly social species, individuals frequently face opportunities to cooperate. The molecular and neural mechanisms that integrate internal and external information prior to cooperative responses are not well understood. Using expression levels of egr-1 , a genomic marker of neural activity, we quantified the neural response to an alloparental-care opportunity in a cooperatively breeding fish, a component of cooperative behaviour, across brain regions and time. In this species, alloparental care and submission are considered alternative strategies to appease dominants. We therefore investigated whether brood care and defence as well as submissive displays were associated with egr-1 expression. Finally, we predicted potential targets of the egr-1 transcription factor in the cichlid genome. This target prediction suggested that egr-1 regulates the expression of transcription factors involved in nervous system development, which could be implicated in social memory formation associated with cooperation. Egr-1 expression levels differed between test and control individuals and across time. Compared to a control, individuals experiencing the cooperation opportunity expressed less egr-1 in two brain regions, the cerebellum and the telencephalon. This down-regulation was independent of their behavioural reaction, i.e. whether they cooperated or not. However, within the subset of test individuals, egr-1 expression increased as a function of the amount of submissive behaviours, but not of cooperative behaviours, in the hypothalamus and potentially the telencephalon. These regions host structures that play a role in social decision-making; suggesting that egr-1 might be a suitable proxy for neural activation due to the social interaction component of the cooperation opportunity, rather than the actual alloparental care component. Highlights • Egr-1 was down-regulated in the cerebellum and the telencephalon of test fish • This down-regulation was independent of the amount of cooperative behaviours • More submissive test fish had higher egr-1 expression in two brain regions • Egr-1 regulates transcription factors involved in nervous system development • Egr-1 alone is not a suitable marker for neural activation due to alloparental care [ABSTRACT FROM AUTHOR]