Data from: Mechanisms of biotic resistance across complex life cycles

1. Biotic resistance is the ability of communities to inhibit the establishment, spread or impact of novel species. However, the interactions that underlie biotic resistance depend heavily on the contexts in which species interact. Consequently, studies of biotic resistance that consider single processes, patches, species or life-history stages may provide an incomplete picture of the capacity for communities to resist invasion. 2. Many organisms have multiphasic life cycles, where individuals can occupy distinct niches at different stages of the life-history. Generally, studies of biotic resistance focus on interactions within a single life-history stage, and interactions at other life-history stages are overlooked. Here, we demonstrate that different mechanisms of biotic resistance occur across the life history and together limit the invasion success of an introduced marine invertebrate (Ciona intestinalis) in northern California. 3. We tested the role of interactions (competition and predation) with the resident community in limiting the abundance of Ciona through experiments conducted on fertilization, larval survival, settlement, early post-settlement survival, and the survival of juveniles and adults. 4. Under some circumstances, Ciona became abundant in mid-successional stages and showed more rapid growth rates than a morphologically similar native species, Ascidia ceratodes. However, predators reduced Ciona abundance much more than that of Ascidia at several life stages. 5. Furthermore, Ciona appeared to be a weaker competitor at the adult stage. Early life-history interactions with other sessile species at the fertilization, larval and recruit stages had modest to no effects on Ciona abundance. 6. The presence of biotic resistance mechanisms acting at multiple life stages, and potentially under different conditions, suggests that different components of biotic resistance interact to enhance the resident community's resistance to invasion.

1. 生物抵抗（biotic resistance）指群落抑制外来物种定殖、扩散或产生影响的能力。然而，支撑生物抵抗的种间相互作用高度依赖于物种相互作用发生的情境。因此，仅关注单一过程、生境斑块、物种或生活史阶段的生物抵抗研究，可能无法完整反映群落抵御入侵的能力。2. 许多生物具有多阶段生活史，其个体在生活史的不同阶段可占据不同生态位。通常而言，生物抵抗相关研究多聚焦于单一生活史阶段内的种间相互作用，而忽略了其他阶段的相互作用。本研究表明，贯穿整个生活史的不同生物抵抗机制共同限制了一种引入性海洋无脊椎动物——玻璃海鞘（Ciona intestinalis）在北加利福尼亚海域的入侵成功。3. 本研究通过针对受精、幼虫存活、附着、附着后早期存活以及稚体与成体存活的一系列实验，检验了与本地群落的相互作用（竞争与捕食）在限制玻璃海鞘种群丰度中的作用。4. 在部分情境下，玻璃海鞘在演替中期阶段种群丰度较高，且生长速率快于形态相似的本地物种角皮海鞘（Ascidia ceratodes）。但在多个生活史阶段中，捕食者对玻璃海鞘种群丰度的抑制作用远强于角皮海鞘。5. 此外，玻璃海鞘在成体阶段的竞争能力较弱。在受精、幼虫以及稚体阶段，与其他固着物种的早期生活史相互作用对玻璃海鞘的种群丰度仅有微弱甚至无影响。6. 多个生活史阶段（且可能在不同情境下）发挥作用的生物抵抗机制的存在，表明生物抵抗的不同组分相互协作，强化了本地群落抵御入侵的能力。