Kiehnau Emily L, Weider Lawrence J
Graduate Program in Ecology and Evolutionary Biology, Department of Biology, University of Oklahoma, Norman, OK, 73019, USA.
Oecologia. 2019 Aug;190(4):799-809. doi: 10.1007/s00442-019-04461-6. Epub 2019 Jul 11.
Chemical cues are used by many taxa to communicate within and among species. Behavioral defenses induced by predator cues are a mechanism by which prey species resist or avoid predator attack. This study examined the egg bank of native Daphnia species in a lake that has been invaded by Bythotrephes longimanus, an invertebrate zooplanktivore native to northern-central Europe and Asia (initial invasion 1994, population boom in 2009). Daphnia resting eggs from both pre- and post-B. longimanus invasion lake sediments were hatched and established as isofemale clonal lines. Phototactic behavior (a proxy for vertical migration behavior) was assessed in the presence and absence of B. longimanus cue. This was done to evaluate the hypothesis that the heavy predation imposed by B. longimanus would have been selected for Daphnia clones that are more negatively phototactic in the presence of B. longimanus cue, because B. longimanus is a visual predator. The behavior of the clones derived from pre-B. longimanus era resting eggs was not significantly different from the behavior of the clones from the post-B. longimanus era and exposure to predator cue did not affect the phototactic response of the clones. There was a significant difference in the phototactic behavior of the three Daphnia species tested (Daphnia ambigua, Daphnia mendotae, and Daphnia pulicaria). These results suggest that predation by B. longimanus is not the main factor that is influencing the phototactic behavior of Daphnia in the lake. Other factors such as fish predation may be playing a more significant role in this system.
许多生物分类群利用化学信号在物种内部和物种之间进行交流。捕食者信号诱导的行为防御是猎物物种抵抗或避免捕食者攻击的一种机制。本研究调查了一个湖泊中本地水蚤物种的卵库，该湖泊已被长刺溞入侵，长刺溞是一种原产于欧洲中北部和亚洲的无脊椎浮游动物捕食者（1994年首次入侵，2009年种群数量激增）。将长刺溞入侵前后湖泊沉积物中的水蚤休眠卵孵化，并建立为同雌系克隆品系。在有和没有长刺溞信号的情况下评估趋光行为（垂直迁移行为的替代指标）。这样做是为了评估以下假设：由于长刺溞是视觉捕食者，长刺溞施加的严重捕食压力会选择在长刺溞信号存在时更具负趋光性的水蚤克隆。来自长刺溞入侵前时代休眠卵的克隆行为与来自长刺溞入侵后时代克隆的行为没有显著差异，并且暴露于捕食者信号不会影响克隆的趋光反应。所测试的三种水蚤物种（模糊水蚤、门多塔水蚤和蚤状水蚤）的趋光行为存在显著差异。这些结果表明，长刺溞的捕食不是影响该湖泊中水蚤趋光行为的主要因素。其他因素，如鱼类捕食，可能在这个系统中发挥更重要的作用。
