Department of Biology, Temple University, Philadelphia, PA, United States of America.
PLoS One. 2019 Sep 6;14(9):e0221969. doi: 10.1371/journal.pone.0221969. eCollection 2019.
Invasive predators have caused rapid declines in many native prey species across the globe. Predator invasion success may be attributed to prey naïveté, or the absence of anti-predator behavior between native and non-native species. An understanding of the effects of naïveté at different timescales since introduction and across multiple trophic levels is lacking, however, particularly in marine systems. Given the central role of trophic interactions in invasion dynamics, this knowledge gap limits the ability to predict high impact predator invasions. Naïveté was examined across three trophic levels of marine invertebrates: a native basal prey (hard clam), two non-native intermediate predators (the recently-introduced Asian shore crab and the long-established European green crab), a native intermediate predator (juvenile blue crabs), and a native top predator (adult blue crab). We hypothesized that naïveté would be more pronounced in trophic interactions involving the recently-introduced non-native predator in comparison to the long-established non-native and native intermediate predators. We further hypothesized that the recently-introduced intermediate predator would both benefit from naïveté of the native basal prey and be hindered by higher mortality through its own naïveté to the native top predator. To test these hypotheses, three laboratory experiments and a field experiment were used. Consistent with our hypotheses, basal prey naïveté was most pronounced with the recently-introduced intermediate predator, and this increased the predator's foraging success. This recently-introduced intermediate predator, however, exhibited an ineffective anti-predator response to the native top predator, and was also preyed upon more in the field than its long-established and native counterparts. Therefore, despite direct benefits from basal prey naïveté, the recently-introduced intermediate predator's naïveté to its own predators may limit its invasion success. These results highlight the importance of a multi-trophic perspective on predator-prey dynamics to more fully understand the consequences of naïveté in invasion biology.
入侵捕食者已导致全球许多本地猎物物种迅速减少。捕食者的入侵成功可能归因于猎物的天真，即本地和非本地物种之间缺乏防御捕食者的行为。然而，人们对引入后不同时间尺度和多个营养级别的天真影响的了解仍存在差距，特别是在海洋系统中。鉴于营养相互作用在入侵动态中的核心作用，这一知识空白限制了预测高影响捕食者入侵的能力。本研究考察了海洋无脊椎动物的三个营养级别的天真程度：一个本地基础猎物（硬壳蛤）、两个新引入的非本地中间捕食者（最近引入的亚洲滨蟹和长期存在的欧洲绿蟹）、一个本地中间捕食者（幼年蓝蟹）和一个本地顶级捕食者（成年蓝蟹）。我们假设，与长期存在的非本地和本地中间捕食者相比，新引入的非本地捕食者的营养相互作用中，天真程度更为明显。我们进一步假设，新引入的中间捕食者既受益于本地基础猎物的天真，也因自身对本地顶级捕食者的天真而面临更高的死亡率。为了验证这些假设，本研究使用了三个实验室实验和一个野外实验。与我们的假设一致，新引入的中间捕食者对本地基础猎物的天真程度最为明显，这增加了捕食者的觅食成功率。然而，这种新引入的中间捕食者对本地顶级捕食者表现出无效的防御捕食者的反应，并且在野外比其长期存在的和本地的同类更容易被捕食。因此，尽管新引入的中间捕食者从本地基础猎物的天真中直接受益，但它对自身捕食者的天真可能限制了其入侵成功。这些结果强调了从多营养级角度研究捕食者-猎物动态的重要性，以更全面地了解入侵生物学中天真的后果。
