Abstract
In social animals that form flocks, individuals compete or cooperate to gain access to shared resources. In particular, group-foraging individuals frequently engage in aggressive interactions with conspecifics, including threat displays and physical attacks, in order to acquire food resources. Here, we investigated social interactions in flocks of captive tree sparrows (Passer montanus) to observe the formation of dominance hierarchies. We also examined correlations between social status and morphological traits to identify which physical traits act as indicators of dominance. To do so, we recorded aggressive behaviours (attacks and threats) of tree sparrows caught in two distinct regions in the Republic of Korea (Gwangju and Gurye). After merging the two groups, we examined dominance structures using David’s scores for one month, and we recorded 1,051 aggressive interactions at a feeder in a group of 19 individuals. Using the number of aggressions and attack and threat behaviours, we tested whether morphological traits and sex influenced dominance structures. Aggressions were significantly more frequent in males than in females. However, no significant difference was observed the frequency of between- and within-sex aggression. In addition, differences in the frequency of aggression behaviours were observed between capture-site groups. Dominance structure was significantly correlated with certain morphological traits; specifically, the frequency of attacking behaviours was correlated with bill-nose length, and the frequency of threat displays was correlated with sex and badge size. These results suggest that social signals are closely related to morphological traits that are used to form dominance hierarchies in tree sparrow flocks.
Introduction: The growing prevalence of obesity and related type 2 diabetes is reaching epidemic proportions in the Gulf countries. Oxidative damage and inflammation are possible mechanisms linking obesity to diabetes and other related complications, including cardiovascular disease (CVD).
Aims: To measure the effects of increased fruit and vegetable consumption on body weight, waist circumference, oxidative damage, and inflammatory markers.
Materials and Methods: We recruited and followed up with 965 community free-living subjects. All recruited subjects had fruit and vegetable intakes, physical activity, antioxidants, and markers of oxidative damage and inflammation measured at baseline and follow up. A validated, semi-quantitative food-frequency questionnaire was used to assess subjects’ fruit and vegetable consumption. We stratified subjects based on their daily fruit and vegetable consumption and compared metabolic risk factors between those with high fruit and vegetable consumption and those with low consumption. A multiple logistic regression analysis was performed to determine the independent effects of fruit and vegetable intake on changes in body weight and waist circumference (WC).
Results: A total of 965 community free-living subjects (801 (83%) females, mean (SD) age 39 ± 12 years) were recruited and followed up with for a mean (SD) period of 427 ± 223 days. Using WHO cut-off points for body mass index (BMI), 284 (30%) subjects were overweight and 584 (62%) obese, compared to 69 (8%) at normal body weight. An increased fruit and vegetable consumption was associated with a significant decrease in inflammatory markers (hs CRP, TNF-α) and oxidative damage markers (TBARs) and with increased antioxidant enzymes (catalase, glutathione peroxidase) compared to a low consumption (p < 0.05). The benefits of an increased fruit and vegetable consumption in obese subjects was independent of changes in body weight and WC and was maintained at follow up.
Conclusion: Our results support the beneficial role of a higher fruit and vegetable intake in obese subjects independent of changes in body weight and WC.
Forced loss lowers social ranks and induces depressive-like behaviors
Forced loss generates negative reward prediction error
Forced loss but not natural loss activates LH-LHb circuit and induces LHb bursting
LHb burst firing inhibits mPFC and reinforces subordination
Summary
Downward social mobility is a well-known mental risk factor for depression, but its neural mechanism remains elusive. Here, by forcing mice to lose against their subordinates in a non-violent social contest, we lower their social ranks stably and induce depressive-like behaviors. These rank-decline-associated depressive-like behaviors can be reversed by regaining social status. In vivo fiber photometry and single-unit electrophysiological recording show that forced loss, but not natural loss, generates negative reward prediction error (RPE). Through the lateral hypothalamus, the RPE strongly activates the brain’s anti-reward center, the lateral habenula (LHb). LHb activation inhibits the medial prefrontal cortex (mPFC) that controls social competitiveness and reinforces retreats in contests. These results reveal the core neural mechanisms mutually promoting social status loss and depressive behaviors. The intertwined neuronal signaling controlling mPFC and LHb activities provides a mechanistic foundation for the crosstalk between social mobility and psychological disorder, unveiling a promising target for intervention.
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Reply to Male birds with larger bills were found to be significantly more aggressive and have higher social status than their smaller billed counterparts by Zadarex
Abstract
In social animals that form flocks, individuals compete or cooperate to gain access to shared resources. In particular, group-foraging individuals frequently engage in aggressive interactions with conspecifics, including threat displays and physical attacks, in order to acquire food resources. Here, we investigated social interactions in flocks of captive tree sparrows (Passer montanus) to observe the formation of dominance hierarchies. We also examined correlations between social status and morphological traits to identify which physical traits act as indicators of dominance. To do so, we recorded aggressive behaviours (attacks and threats) of tree sparrows caught in two distinct regions in the Republic of Korea (Gwangju and Gurye). After merging the two groups, we examined dominance structures using David’s scores for one month, and we recorded 1,051 aggressive interactions at a feeder in a group of 19 individuals. Using the number of aggressions and attack and threat behaviours, we tested whether morphological traits and sex influenced dominance structures. Aggressions were significantly more frequent in males than in females. However, no significant difference was observed the frequency of between- and within-sex aggression. In addition, differences in the frequency of aggression behaviours were observed between capture-site groups. Dominance structure was significantly correlated with certain morphological traits; specifically, the frequency of attacking behaviours was correlated with bill-nose length, and the frequency of threat displays was correlated with sex and badge size. These results suggest that social signals are closely related to morphological traits that are used to form dominance hierarchies in tree sparrow flocks.