Paul Matthew J, Indic Premananda, Schwartz William J
Department of Psychology, University at Buffalo, SUNY, Buffalo, NY 14260, USA
Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
Biol Lett. 2015 Jun;11(6):20150204. doi: 10.1098/rsbl.2015.0204.
Communal animals often engage in group activities that require temporal synchrony among its members, including synchrony on the circadian timescale. The principles and conditions that foster such collective synchronization are not understood, but existing literature hints that the number of interacting individuals may be a critical factor. We tested this by recording individual circadian body temperature rhythms of female house mice housed singly, in twos (pairs), or in groups of five (quintets) in constant darkness; determining the daily phases of the circadian peak for each animal; and then calculating the cycle-to-cycle phase relationship between cohabiting animals over time. Significant temporal coherence was observed in quintets: the proportion of quintets (4/7), but not pairs (2/8), that became synchronized was greater than could be achieved by the complete simulated reassortment of all individuals. We speculate that the social coupling of individual circadian clocks of group members may be adaptive under certain conditions, and we propose that optimal group sizes in nature may depend not only on species-specific energetics, spatial behaviour and natural history but also on the mathematics of synchronizing assemblies of weakly coupled animal oscillators.
群居动物经常参与需要其成员之间时间同步的群体活动，包括昼夜节律时间尺度上的同步。促进这种集体同步的原理和条件尚不清楚，但现有文献暗示，相互作用的个体数量可能是一个关键因素。我们通过记录雌性家鼠在持续黑暗中单独饲养、成对饲养（两只一组）或五只一组饲养时的个体昼夜体温节律来对此进行测试；确定每只动物昼夜峰值的每日相位；然后计算同居动物随时间的周期到周期相位关系。在五只一组的群体中观察到了显著的时间一致性：五只一组（4/7）而非两只一组（2/8）中实现同步的比例大于通过对所有个体进行完全模拟重新组合所能达到的比例。我们推测，在某些条件下，群体成员个体昼夜节律时钟的社会耦合可能具有适应性，并且我们提出，自然界中的最佳群体规模可能不仅取决于物种特有的能量学、空间行为和自然史，还取决于弱耦合动物振荡器同步集合的数学原理。
