Evolution of warfare by resource raiding favors polymorphism in belligerence and bravery

From protists to primates, intergroup aggression and warfare over resources has been observed in several taxa whose populations typically consist of groups connected by limited genetic mixing. Here, we model the co-evolution between four traits relevant to this setting: (i) investment into common-pool resource production within groups ('helping'); (ii) proclivity to raid other groups to appropriate their resources ('belligerence'); and investments into (iii) defense and (iv) offense of group contests ('defensive and offensive bravery'). We show that when traits co-evolve, the population often experiences disruptive selection favouring two morphs: 'Hawks', who express high levels of both belligerence and offensive bravery; and 'Doves', who express neither. This social polymorphism involves further among-traits associations when the fitness costs of helping and bravery interact. In particular if helping is antagonistic with both forms of bravery, co-evolution leads to the coexistence of individuals that either: (i) do not participate into common-pool resource production but only in its defense and appropriation ('Scrounger Hawks'); or (ii) only invest into common pool resource production ('Producer Doves'). Provided groups are not randomly mixed, these findings are robust to several modelling assumptions. This suggests that inter-group aggression is a potent mechanism in favoring within-group social diversity and behavioural syndromes.

Restless Rainbows And Bold Browns: Personality of Domesticated Trout Predicts Invasiveness And Impact

Personality and behavioural syndromes are increasingly recognised in many animal species and are now seen as critical to the prediction of non-native species success and impacts. Rainbow trout and brown trout have been introduced globally, but differ in patterns of establishment success and ecological impact. While environmental tolerance may be a driver, thus far the role of behaviour has not been rigorously tested. Here, we investigated whether diploid rainbow trout and diploid and triploid brown trout differ among several key behavioural measures linked to invasibility. We assessed activity, boldness, aggression, and feeding, using open field, novel object, shelter, mirror, feeding, and functional response experiments. We also tested within each fish type for behavioural syndromes comprising correlations among activity, boldness and aggression. Rainbow trout were more active and aggressive but less bold than diploid and triploid brown trout. In small groups, however, rainbow trout were bolder than both types of brown trout. Diploid brown trout were more active and bolder than triploids when tested individually. There was no association between activity and boldness in rainbow trout, but there was in both brown trout. The increased activity and aggression of rainbow trout may reflect an increased stress response to novel situations, with this response reduced in a group. These results suggest that rainbow trout do not manage their energy budgets effectively, and may explain why they are implicated in fewer ecological impacts. Comparative analyses of multiple behaviours of invasive species and genetic variants may thus be key to understanding and predicting invader success and ecological impacts.

Captivity-induced behaviour and spatial learning abilities in an enigmatic, aquifer-dwelling blind eel, Rakthamichthys digressus

We investigated the impact of captive life on behaviour and learning abilities in an enigmatic, aquifer-dwelling blind eel, Rakthamichthys digressus. Of eight major behavioural traits related to exploration and activity in a novel arena, four were significantly altered by life in captivity. While the startle response upon introduction into the arena and overall swimming away from the walls increased after captivity, inactivity exhibited immediately after the startle and the reaction to an external disturbance decreased. We also observed behavioural syndromes between startle responses and horizontal wall following, and between overall activity and vertical wall following; however, these behavioural syndromes were not altered by maintenance in captivity. Interestingly, this blind-eel failed to learn a simple spatial task in a Y-maze apparatus. Captive-associated behavioural changes in R. digressus may influence their survival after reintroduction into natural habitats, and such changes must be taken into account while developing protocols for ex-situ conservation and subsequent release.

Effects of male and female personality on sexual cannibalism in the Springbok mantis

Behaviours that are consistent across contexts (also known as behavioural syndromes) can have evolutionary implications, but their role in scenarios where the sexes conflict, such as sexual cannibalism, is poorly understood. The aggressive spillover hypothesis proposes that cannibalistic attacks during adulthood may depend on female aggressiveness during earlier developmental stages, but evidence for this hypothesis is scarce. Male activity may also influence sexual cannibalism if males approach females quickly and carelessly, yet this has not been explored. Here we use the Springbok mantis, Miomantis caffra, to explore whether male activity levels and female aggressiveness can explain high rates of sexual cannibalism prior to copulation. We show that male and female personality traits affect male mating decisions, but not sexual cannibalism. Females that were aggressive as juveniles were not more likely to cannibalize males when adult, but these females were approached by males more frequently. More active males were more likely to approach females, but they were neither faster at doing so nor were they more likely to be cannibalized. We also found that size and age influenced mating decisions of both sexes: young females were more like to cannibalize males while young and large males took longer to approach females. Taken together, our results suggest that several traits, including personality, play a role in sexual encounters in M. caffra. Our study further highlights the importance of examining the traits of both sexes when assessing mating dynamics, especially in the context of sexual cannibalism.

Time Perspective among Patients Diagnosed with Neurotic and Personality Disorders − an Exploratory, Clinical Study

(1) An assessment of the structure of time perspective (TP) in a group of patients with neurotic and personality disorders (ICD-10: F4x, F60.x, F61) treated with group psychotherapy. (2) An analysis of the differences between the structure of TP in patients and the general population in order to expand the understanding of the relations between TP and mental health. Data were collected from 49 patients at the University Hospital Day Centre for the Treatment of Neurotic Disorders and Behavioural Syndromes. The measurement of TP was performed with the Zimbardo Time Perspective Inventory. A licensed psychiatrist conducted the diagnosis of neurotic and personality disorders, with additional data obtained from the Symptom Checklist KO ‘O’ and the Neurotic Personality Questionnaire KON-2006. The statistical analysis revealed significant differences in the structure of TP between patients and the general population. Among patients, the intensity of the past experienced negatively was significantly higher, and subsequently, the degree of the past experienced positively was lower. Patients remain in the negative past and concentrate much more on the pain and the worrying memories. They give much less attention to what was and what is valuable and pleasant in their life. Results of this research reveal distinct features of the structure of TP in the studied group. Findings underline the clinical relevance of TP at various stages of therapy. Restoring a balanced time perspective could be regarded as a tenable goal for psychotherapy and perhaps an innovative indicator of the treatment’s effectiveness.

Dysregulation of circRNA Expression in the Peripheral Blood of Individuals With Schizophrenia and Bipolar Disorder

Circular RNA (circRNA) are head-to-tail back-spliced RNA transcripts that have been linked to several biological processes and their perturbation is evident in human diseases, including neurological disorders. There is also emerging research suggesting circRNA expression may also be altered in psychiatric and behavioural syndromes. Here, we provide a comprehensive analysis of circRNA expression in peripheral blood mononuclear cells (PBMCs) from 39 patients with schizophrenia and bipolar disorder as well as 20 healthy individuals using deep RNA-seq. We observed systematic alternative splicing leading to a complex and diverse profile of RNA transcripts including 8,762 high confidence circRNAs. More specific scrutiny of the circular transcriptome in schizophrenia and bipolar disorder, compared to a non-psychiatric control group, revealed significant dysregulation of 55 circRNAs with a bias towards downregulation. These molecules were predicted to interact with a large number of miRNAs that target genes enriched in psychiatric disorders. Further replication and cross validation to determine the specificity of these circRNAs across broader diagnostic groups and subgroups in psychiatry will enable their potential utility as biomarkers to be established.

Behavioural repeatability in the Big Brown Bat, Eptesicus fuscus

Work on animal personality, characterized by high behavioural repeatability, shows that animals exhibit limits to plasticity, with an individual’s range of variation only covering a portion of the range observed across the entire population. This work is particularly important for understanding the underlying genetic basis of behaviours. While research on behavioural repeatability has spanned many taxa, little work has focused on bats. Our objective was to determine if big brown bats (Eptesicus fuscus) exhibit moderate to high repeatability of different behavioural traits and if behavioural syndromes (among-individual correlations between behaviours) are present. Using a captive population, repeatability was assessed for aggression, exploration, and activity. Moderate repeatabilities were observed for all behaviours, indicating that individuals exhibit consistent behaviour over time. There were no significant correlations among behaviours. Future research aimed at assessing how changes in social structure impact behavioural repeatability will be valuable for understanding behavioural plasticity in social bat species.