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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.

The function of cooperative traits can change over time. For example, helping behaviors that originally evolved by kin selection can later yield direct fitness benefits and be stabilized by partner choice. In such cases, there may be multiple interacting factors that drive cooperation. Here, I review evidence that food sharing in vampire bats evolved as form of extended maternal care that was co‐opted to yield reciprocal benefits, and that such reciprocal relationships may have led to investment strategies that balance the trade‐offs between greater quality and quantity of cooperative relationships. [ABSTRACT FROM AUTHOR]

Evolutionary medicine is a concept that arose mainly in the 1990s, and which applies evolutionary biological principles to human medical fields. For instance, evolutionary medicine proposed that there is an evolutionary mismatch between the human anatomy and physiology and novel, man‐made environments, leading to the so‐called diseases of civilization. Constraints exist on the process of natural selection, and evolutionary trade‐offs can prevent traits from being optimal, leaving humans with traits that at first sight seem maladaptive, such as the very narrow birth canal of humans. More generally, certain traits can increase reproduction at the cost of health and longevity. Other traits, such as pain and fever, are related to protective physiological defences, and not diseases. Some medical topics have biological roots in the field of ethology, particularly human ethology, such as the behavioural aspects of psychiatry and addiction. Compulsive overeating and binge eating show similarities to substance‐linked addictions and behavioural addictions. Interactions between behaviour, stress and diseases have ancient evolutionary roots, which may lead to a mismatch to the modern human environment. A subject of high, topical interest is the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) pandemic, as the behavioural aspects of population compliance are crucial for the success in fighting the pandemic. Ethology, and evolutionary biology in general, can substantially contribute to improving the biological understanding of medical phenomena, and therefore of medical and public health interventions. This applies not only to research but also to education. [ABSTRACT FROM AUTHOR]

Behavioural reactions towards a mirror image are frequently used to measure individual aggression in a standardized way, especially in fishes. However, this approach was criticized recently on several grounds. One point of concern is that mirror tests are often conducted under highly artificial laboratory settings, while there exists a lack of knowledge of how individuals will react towards their reflection in the wild. We measured the responses of eight sympatric lamprologine cichlid species towards their mirror images in their natural environment in Lake Tanganyika. All species reacted by showing aggression towards their mirror image. The occurrence of overt and restrained aggression varied between species, reflecting species‐specific aggressive behaviours. The finding that larger species showed a higher amount of overt attacks further supports this interpretation. A commonality across all species was that aggression escalated over time, resembling behavioural patterns during prolonged aggressive encounters between life opponents with similar resource holding potential. These results shed light on the behaviour of closely related fish species towards their mirror image under natural conditions and contribute knowledge to the ongoing discussion on the suitability of mirror tests when measuring aggression. [ABSTRACT FROM AUTHOR]

Conflicts between stable social groups ("intergroup conflicts") can be damaging and exert a strong influence on within‐group social behaviour. The success of groups during intergroup conflict may depend on the ability of individual group members to converge upon collective defence behaviour, such as approaching or attacking. In principle, collective defence can be achieved via a united front, in which each individual responds in the same way to an intergroup threat. We tested the impact of simulated intergroup conflicts on collective defence and individual behaviour in banded mongooses (Mungos mungo), a cooperatively breeding mammal in which intergroup conflict is particularly common and costly. We presented focal groups with scent markings, call playbacks and caged live animals from rival groups and compared their responses to these stimuli with their responses to own‐group control stimuli. A greater proportion of group members approached the stimulus and acted defensively in response to rival stimuli as compared to controls, consistent with a unified collective defence response. However, counter to our expectation, groups exhibited lower behavioural homogeneity when presented with rival stimuli as compared to controls. A closer examination of the behaviours competitors used revealed that lower homogeneity was driven by a greater use, and diversity, of defensive behaviours relevant to repelling simulated rivals. Finally, group size affected responses: as group size increased, the proportion of members approaching the stimulus and behavioural homogeneity decreased. Our results lend support to the hypothesis that intergroup conflict leads to coordinated collective defence behaviour during the immediate threat of an intergroup conflict. However, collective defence need not mean that all group members execute the same behaviours. [ABSTRACT FROM AUTHOR]

It has been proposed that naked mole‐rat (Heterocephalus glaber) societies resemble those of eusocial insects by showing a division of labour among non‐breeding individuals. Earlier studies suggested that non‐breeders belong to distinct castes that specialise permanently or temporarily in specific cooperative tasks. In contrast, recent research on naked mole‐rats has shown that behavioural phenotypes are continuously distributed across non‐breeders and that mole‐rats exhibit considerable behavioural plasticity suggesting that individuals may not specialise permanently in work tasks. However, it is currently unclear whether individuals specialise temporarily and whether there is a sex bias in cooperative behaviour among non‐breeders. Here, we show that non‐breeding individuals vary in overall cooperative investment, but do not specialise in specific work tasks. Within individuals, investment into specific cooperative tasks such as nest building, food carrying and burrowing is positively correlated, and there is no evidence that individuals show trade‐offs between these cooperative behaviours. Non‐breeding males and females do not differ in their investment in cooperative behaviours and show broadly similar age and body mass related differences in cooperative behaviours. Our results suggest that non‐breeding naked mole‐rats vary in their overall contribution to cooperative behaviours and that some of this variation may be explained by differences in age and body mass. Our data provide no evidence for temporary specialisation, as found among some eusocial insects and suggest that the behavioural organisation of naked mole‐rats resembles that of other cooperatively breeding vertebrates more than that of eusocial insect species. [ABSTRACT FROM AUTHOR]

Cooperative behaviour often co‐occurs with the defence of key resources, typically in the form of a breeding site or territory communally exploited by a group of cooperating individuals. Nevertheless, not all animals that defend resources evolve advanced forms of cooperation and sociality—many non‐cooperative species occupy resources that do not differ in obvious ways from those inhabited by cooperative species. A key question is thus whether cooperation confers more subtle benefits, for example by allowing access to higher quality resources through competitive exclusion of less social rivals. In other words, it is not clear whether defendable resources are a necessary precondition for sociality or whether they also contribute to the maintenance and enhancement of cooperative societies. Here, we highlight how advances in imaging technology, machine‐learning, and environmental reconstruction enable the collection of behavioural and ecological data in unparalleled quantity and quality to address this question. These new techniques are especially suited to compare small‐scale differences in resource use between cooperative and non‐cooperative species that share a general habitat and have similar ecologies. The lamprologine cichlids of Lake Tanganyika are a prominent example of such a system and Michael Taborsky's pioneering work on this group has done much to promote these fishes as models of social evolution. We show that habitat features indicative of increased resource quality, namely increased stone cover, are indeed associated with the distribution of cooperative cichlids—at least where these resources are relatively scarce. We thus support a point Michael Taborsky made in 1981: the evolution of cooperative behaviour among cichlids is tied to their close association with a crucial resource, the substrate in which they hide and breed. In the future, the techniques we introduce here will allow to also investigate whether this substrate is indeed more than just the necessary precondition for cooperation among fishes; in addition, they will likely find application in a wide range of research fields interested in the interplay between biotic and abiotic environmental factors. [ABSTRACT FROM AUTHOR]

The social environment encountered early during development can temporarily or permanently influence life history decisions and behaviour of individuals and correspondingly shape molecular pathways. In the highly social cichlid fish Neolamprologus pulcher, deprivation of brood care permanently affects social behaviour and alters the expression of stress axis genes in juveniles and adults. It is unclear when gene expression patterns change during early life depending on social experience, and which genes are involved. We compared brain gene expression of N. pulcher at two time points during the social experience phase when juveniles were reared either with or without brood care, and one time point shortly afterwards. We compared (a) whole transcriptomes and (b) expression of 79 genes related to stress regulation, in order to define a neurogenomic state of stress for each fish. At developmental day 75, that is, after the social experience phase, 43 genes were down‐regulated in fish having experienced social deprivation, while two genes involved in learning and memory and in post‐translational modifications of proteins (PTM), respectively, were up‐regulated. Down‐regulated genes were mainly associated with immunity, PTM and brain function. In contrast, during the experience phase no genes were differentially expressed when assessing the whole transcriptome. When focusing on the neurogenomic state associated with the stress response, we found that individuals from the two social treatments differed in how their brain gene expression profiles changed over developmental stages. Our results indicate that the early social environment influences the transcriptional activation in fish brains, both during and after an early social experience, possibly affecting plasticity, immune system function and stress axis regulation. [ABSTRACT FROM AUTHOR]