摘要:化学预警信息（Chemical alarm cue，CAC）在鱼类捕食者-猎物关系中发挥重要作用，并与二者生存适合度密切关联。繁殖期鱼类的繁殖生理投入和化学预警响应均具有较高的能量需求，因而可能存在某种程度上的生存-繁殖的权衡（Trade-off）。选取高体鳑鲏（Rhodeus ocellatus，卵生，繁殖投入较低）、斑马鱼（Danio rerio，卵生，繁殖投入较高）、孔雀鱼（Poecilia reticulata，卵胎生，繁殖投入较高）和皮球鱼（Poecilia latipinna，卵胎生，繁殖投入很高）等繁殖方式各异、能量投入不同的4种淡水鱼类为实验对象，测定了繁殖IV期实验鱼对不同浓度的化学预警信息（Damage-released chemical alarm cues，DCAC）的行为响应模式，并探究了4种实验鱼的化学预警响应与其性腺指数（Gonadosomatic index，GSI）的关联。结果表明：（1）DCAC对4种实验鱼的空间分布、活跃状态、逃逸行为等大部分化学预警响应参数均有不同程度的影响（P<0.05）；（2）4种实验鱼GSI与其化学预警响应参数的变化无显著相关性（P>0.05）（除高浓度DCAC处理组皮球鱼GSI与底栖时间的变化负相关外）。研究回答了长期以来有关繁殖期鱼类化学预警通讯是否缺失的问题，证实了繁殖期不同繁殖生理投入/繁殖对策的4种淡水鱼类均有显著的化学预警响应，提示鱼类GSI与其化学预警响应程度通常不相关（仅高风险环境下繁殖生理投入很高的物种中可能呈现负相关）。



Abstract:Chemical alarm cue (CAC) plays an important role in the fish predator-prey interactions and is closely related to species fitness. In recent years, it has become a focus of behavioral ecology, conservation biology, and restoration ecology. Epidermal-damage-released chemical cues (DCAC) are typically released during a predation event and, therefore, serve as a reliable indicator of immediate predation risk. The sensitive avoidance of predation risk sources allows prey to increase their probability of survival by detecting and avoiding potential predators but is costly in terms of reduced foraging or mating opportunities if the emerging chemical cues do not represent an actual threat. Noteworthily, a small number of previous studies have demonstrated that some species of spawning Ostariophysians seasonally lose their alarm pheromone cells and alarm responses to DCAC. Moreover, the correlation between the intensity of chemical alarm responses and reproductive physiological inputs (e.g., gonadosomatic index, GSI) remains largely unexplored. In view of the great energy demand for both breeding inputs and chemical alarm responses during breeding in fish, there may be trade-offs between the two based on energy supply and demand. In this study, four freshwater experimental fishes during reproductive phase IV with significant differences in breeding inputs and breeding strategies were used as the experimental models. They were rose bitterling Rhodeus ocellatus (an egg-laying fish) with very low breeding input, zebrafish Danio rerio (an egg-laying fish) with a bit high breeding input, guppy Poecilia reticulata (a live-bearing fish) with abit high reproductive input, and mollie Poecilia latipinna (a live-bearing fish) with very high reproductive input. The changes in behavioral parameters of the four experimental fishes in response to DCAC were measured using EthoVision XT 9.0 video tracking software. The correlations between the intensity of chemical alarm responses and GSI at different DCAC concentrations in the four experimental fishes were determined. The results showed that the changes in most of the behavioral parameters (i.e., bottom-dwelling time, motionless time, swimming distance, body fill, average speed during the movement and highly mobile time) in the four experimental fishes were significantly affected by DCAC (P<0.05). No significant correlation was found between GSI and changes in the chemical alarm behaviors (P>0.05), except that GSI showed a significantly negative correlation with the change in bottom-dwelling time in the species (i.e., P. latipinna) with the highest breeding input at the high concentration of DCAC (P<0.05). This study answers the long-standing question of whether the chemical alarm communication in breeding fish is weakened or even absent. The findings demonstrated that all four fish species with different breeding inputs during reproductive phase IV had significant behavioral responses to DCAC and suggested that the GSI was not related to the extent of chemical alarm responses in most fish species.





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