Ślusarczyk Mirosław
Department of Hydrobiology, University of Warsaw, Banacha 2, 02-097 Warsaw, Poland e-mail:
Oecologia. 1999 May;119(2):159-165. doi: 10.1007/s004420050772.
The production of diapausing eggs by Daphnia magna stimulated by fish exudates can be explained as an anti-predator defence ensuring genome protection in periods of high risk from fish predation. The combined effects on the induction of D. magna diapause of an "alarm" chemical originating from injured conspecific prey and fish kairomones were tested. The results of the experiment showed that the cues when present together promote both the production of ephippial eggs and male formation, indicating their role in the synchronization of the entire mode of Daphnia sexual reproduction. Ephippial eggs were only produced in the presence of both fish kairomone and conspecific alarm chemicals, while male offspring occurred in the treatments where both, one or none of the cues were present. However, production of males was the highest when both cues were provided. D. magna responded similarly to the tested cues whether or not the hypothetical alarm substance associated with predator odour came from Daphnia specimens actually eaten by fish or from crushed conspecific individuals. However, chemicals from crushed chironomid larvae combined with fish kairomones did not induce a similar response in D. magna. The relative advantage of utilization of alarm cues or predator kairomones in the induction of defence responses in prey organisms is discussed.
大型溞受鱼类分泌物刺激产生滞育卵，这可被解释为一种反捕食防御机制，能在面临鱼类捕食高风险时期确保基因组得到保护。研究测试了源自受伤同种猎物的“警报”化学物质和鱼类信息素对大型溞滞育诱导的综合影响。实验结果表明，当这些信号同时存在时，会促进休眠卵的产生和雄性的形成，这表明它们在大型溞有性繁殖整个模式的同步过程中发挥作用。只有在同时存在鱼类信息素和同种警报化学物质的情况下才会产生休眠卵，而在存在两种信号、一种信号或无信号的处理组中都会出现雄性后代。然而，当两种信号都存在时，雄性的产生量最高。无论与捕食者气味相关的假定警报物质是来自实际被鱼类吃掉的大型溞标本还是来自碾碎的同种个体，大型溞对测试信号的反应都相似。不过，碾碎的摇蚊幼虫的化学物质与鱼类信息素结合后，在大型溞中并未引发类似反应。本文讨论了在诱导猎物生物防御反应中利用警报信号或捕食者信息素的相对优势。
