Abstract
In this study, we investigated the effect of social environment on circadian patterns in activity by group housing either six male or six female mice together in a cage, under regular light–dark cycles. Based on the interactions among the animals, the social dominance rank of individual mice was quantitatively established by calculating Elo ratings. Our results indicated that, during our experiment, the social dominance hierarchy was rapidly established, stable yet complex, often showing more than one dominant mouse and several subordinate mice. Moreover, we found that especially dominant male mice, but not female mice, displayed a significantly higher fraction of their activity during daytime. This resulted in reduced rhythm amplitude in dominant males. After division into separate cages, male mice showed an enhancement of their 24 h rhythm, due to lower daytime activity. Recordings of several physiological parameters showed no evidence for reduced health as a potential consequence of reduced rhythm amplitude. For female mice, transfer to individual housing did not affect their daily activity pattern. We conclude that 24 h rhythms under light–dark cycles are influenced by the social environment in males but not in females, and lead to a decrement in behavioural rhythm amplitude that is larger in dominant mice.
Highlights
Analyses at the ‘group’ level of circadian organization will likely generate a more complex, but more comprehensive, view of clocks and rhythms and their contribution to fitness in nature.—Schwartz and co-workers [1]
We examined whether the presence of social cues can affect the temporal activity patterns in mice housed in regular light–dark cycles and, if so, whether the social dominance hierarchy plays a role in this
We tested the hypothesis that subordinate mice increase their daytime activity due to food restrictions imposed by their dominant nest-mates
Summary
Analyses at the ‘group’ level of circadian organization will likely generate a more complex, but more comprehensive, view of clocks and rhythms and their contribution to fitness in nature.—Schwartz and co-workers [1]. There would not just be benefits, such as stress avoidance [26] or easier access to food resources [27], and costs to the switch of temporal niche such as exposure to predators [28], paired with less or no social protection from predators [29] All these findings are from studies of male mice, and the few data available on female mice suggest that their interactions and the cost– benefit analysis is far more subtle, and possibly more complex [30].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
