鱼群中饥饿个体比例和模拟捕食风险对德玛森小岩鲷群体行为的影响

PERCENTAGE OF STARVED INDIVIDUALS IN A GROUP AND SIMULATED PREDATION RISK ON THE COLLECTIVE BEHAVIOR OF CHINDONGO DEMASONI

  • 摘要: 研究旨在探讨同质(所有个体均正常摄食或饥饿)或异质(由不同饥饿个体比例组成的鱼群)鱼群的隐蔽所利用及觅食行为差异, 以及上述行为对模拟捕食刺激的响应。实验选取喜好集群的德玛森小岩鲷(Chindongo demasoni)幼鱼为研究对象, 以设置了隐蔽所臂和食物臂的六臂迷宫为竞技场, 考察不同饥饿个体比例鱼群(8尾成员, 分别为8F0S、7F1S、4F4S、1F7S和0F8S, F为正常投喂个体, S为饥饿个体), 在自发状态及遭遇模拟捕食刺激下在迷宫不同区域的分布和成群动态。研究发现: (1)8F0S鱼群偏好隐蔽所臂; 随着鱼群饥饿个体成员比例上升, 鱼群在食物臂分布呈线性增加趋势, 0F8S鱼群在隐蔽所臂和食物臂的分布已不再存在差异; (2)隐蔽所臂的鱼群成群频率随饥饿鱼比例的上升呈下降趋势, 但食物臂的鱼群成群频率并未随饥饿鱼比例上升而上升, 且鱼群单次持续时间和总体时间占比均不受鱼群内部饥饿个体占比的影响; (3)模拟捕食刺激导致实验鱼在隐蔽所臂分布显著上升, 应激状态下几乎所有集群均发生在隐蔽所臂, 且该变化不受鱼群组成的影响。研究表明: (1)在陌生环境下德玛森小岩鲷的行为策略是优先避敌, 其次才是营养需求; (2)在实验条件下德玛森小岩鲷的集群行为可能主要由多数群体成员共同决定。

     

    Abstract: Fish are constantly under a dilemma to balance the behaviors of foraging and predator avoidance in their natural habitats. The present study aimed to investigate the balance between sheltering and foraging activities of fish shoal with different percentages of starved individuals, as well as their response to a simulated predation risk. The Chindongo demasoni, a group living cichlid fish species was selected as an experimental model, and a six-arm radius maze equipped with both shelters and food items was used as an observation arena. The fission-fusion dynamics of fish shoals composed of 8 members with different percentages of starved individuals (8F0S, 7F0S, 4F4S, 1F7S and 0F8S, F represents regularly fed member and S represents starved member) were videoed and analyzed. The main results are as follows (1) Regularly fed fish shoal (i.e., 8F0S) showed higher distribution density in the shelter arm compared to other regions of the maze. However, with the increase of starved member, the distribution density showed a linear increase tendency in the food arm, and there had been no significant difference between in shelter- and food-arms in 0F8S. (2) The grouping frequency in shelter arm decreased with the increased number of starved member, however, none of the variables about fission-fusion dynamics in food arm increased with the increased starved member. (3) Simulated predation risk elicited profound increase in grouping in the shelter arm no matter what the shoal composition is. These results suggested that (1) High priority of behavior strategy in C. demasoni is avoiding predation risk when explored in a novel environment. (2) Shoaling behavior of C. demasoni might be decided by majority of group members rather than minority individuals.

     

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