Department of Biological Sciences, Environmental and Conservation Sciences Program, North Dakota State University, PO Box 6050, Fargo, ND 58108, USA.
Biosciences Department, Minnesota State University Moorhead, 1104 7th Avenue South, Moorhead, MN 56563, USA.
Proc Biol Sci. 2022 Aug 31;289(1981):20220752. doi: 10.1098/rspb.2022.0752. Epub 2022 Aug 17.
Predator naiveté has been invoked to explain the impacts of non-native predators on isolated populations that evolved with limited predation. Such impacts have been repeatedly observed for the endangered Pahrump poolfish, , a desert fish species that evolved in isolation since the end of the Pleistocene. We tested Pahrump poolfish anti-predator responses to conspecific chemical alarm cues released from damaged epidermal tissue in terms of fish activity and water column position. Pahrump poolfish behavioural responses to conspecific alarm cues did not differ from responses to a dechlorinated tap water control. As a positive control, the well-studied fathead minnow, , showed significant alarm cue responses in terms of reduced activity and lowered water column position. The density of epidermal club cells, the presumptive source of alarm cues, was significantly lower in Pahrump poolfish relative to fathead minnows. Therefore, anti-predator competence mediated by conspecific alarm cues does not seem to be a component of the ecology of Pahrump poolfish. These findings provide a proximate mechanism for the vulnerability of Pahrump poolfish to non-native predators, with implications for the conservation and management of insular species.
捕食者的天真曾被用来解释非本地捕食者对那些在有限捕食环境下进化的孤立种群的影响。这种影响在濒危的帕伦普湖狼鲈身上反复出现，这是一种自更新世末期以来就与外界隔绝的沙漠鱼类物种。我们根据鱼类的活动和水柱位置，测试了帕伦普湖狼鲈对同种的受损表皮组织释放的化学警报信号的防御反应。帕伦普湖狼鲈对同种警报信号的反应与去氯自来水对照没有区别。作为阳性对照，研究充分的黑头呆鱼在减少活动和降低水柱位置方面表现出明显的警报信号反应。表皮俱乐部细胞的密度，即警报信号的假定来源，在帕伦普湖狼鲈中明显低于黑头呆鱼。因此，由同种警报信号介导的防御捕食能力似乎不是帕伦普湖狼鲈生态的一个组成部分。这些发现为帕伦普湖狼鲈易受非本地捕食者侵害提供了一个近似的机制，并对岛屿物种的保护和管理具有重要意义。
