Tang Zhong-Hua, Wu Hui, Huang Qing, Kuang Lu, Fu Shi-Jian
Laboratory of Evolutionary Physiology and Behavior, Chongqing Key Laboratory of Animal Biology, Chongqing Normal University, Chongqing, China.
PeerJ. 2017 May 30;5:e3397. doi: 10.7717/peerj.3397. eCollection 2017.
Mixed-species shoals of fish are frequently found in the field; however, little is known about individual-level interactions within these groups. We examined the collective motion of two cyprinid species (Chinese bream, , and qingbo, ) that occupy partially overlapping habitats but differ in social behavior (high vs low aggressiveness) and preferred flow regime (slow vs fast water velocity). We extracted measures of collective motion from video recordings of eight replicate groups of four individuals of either Chinese bream or qingbo (conspecific group) or two Chinese bream plus two qingbo (heterospecific group). Chinese bream in conspecific groups showed lower percent time moving and mean swimming speed but a similar speed while moving as compared to the qingbo conspecific groups. However, the difference in mean swimming speed and percent time moving vanished in the heterospecific group as Chinese bream elevated their swimming activity to coordinate with qingbo. This finding suggests that the two species may share similar interaction rules regarding shoaling behavior. The conspecific groups of qingbo exhibited a greater distance between group members than Chinese bream, suggesting a difference in cohesion. However, the inter-individual distances of all fish were similar in the heterospecific group. Qingbo in the heterospecific group swam more frequently at the front compared to Chinese bream, possibly due to their higher activity level. We also measured the startle response to an artificial stimulus and found that there was no significant difference among groups. In conclusion, the present study demonstrated that in the heterospecific groups, Chinese bream elevated their percent time moving while qingbo decreased their inter-individual distance to achieve consistent collective movement; thus, the two species showed similar behavior in the mixed-species group.
在野外经常能发现混合物种的鱼群；然而，对于这些群体中个体层面的相互作用却知之甚少。我们研究了两种鲤科鱼类（鳊鱼和清波）的集体运动，它们占据部分重叠的栖息地，但在社会行为（攻击性高与低）和偏好的水流状态（水流速度慢与快）方面存在差异。我们从八个重复组的视频记录中提取了集体运动的测量值，这些组每组有四条鳊鱼或四条清波（同种群体），或者两条鳊鱼加两条清波（异种群体）。与清波同种群体相比，鳊鱼同种群体的移动时间百分比和平均游泳速度较低，但移动时的速度相似。然而，在异种群体中，随着鳊鱼提高其游泳活动以与清波协调，平均游泳速度和移动时间百分比的差异消失了。这一发现表明，这两个物种在群居行为方面可能共享相似的相互作用规则。清波的同种群体成员之间的距离比鳊鱼更大，这表明在凝聚力方面存在差异。然而，在异种群体中，所有鱼类的个体间距离相似。与鳊鱼相比，异种群体中的清波在前面游动的频率更高，这可能是由于它们的活动水平较高。我们还测量了对人工刺激的惊吓反应，发现各群体之间没有显著差异。总之，本研究表明，在异种群体中，鳊鱼提高了它们的移动时间百分比，而清波则减小了它们的个体间距离以实现一致的集体运动；因此，这两个物种在混合物种群体中表现出相似的行为。
