Data from: Linking native and invader traits explains native spider population responses to plant invasion

Theoretically, the functional traits of native species should determine how natives respond to invader-driven changes. To explore this idea, we simulated a large-scale plant invasion using dead spotted knapweed (Centaurea stoebe) stems to determine if native spiders’ web-building behaviors could explain differences in spider population responses to structural changes arising from C. stoebe invasion. After two years, irregular web-spiders were >30 times more abundant and orb weavers were >23 times more abundant on simulated invasion plots compared to controls. Additionally, irregular web-spiders on simulated invasion plots built webs that were 4.4 times larger and 5.0 times more likely to capture prey, leading to >2-fold increases in recruitment. Orb-weavers showed no differences in web size or prey captures between treatments. Web-spider responses to simulated invasion mimicked patterns following natural invasions, confirming that C. stoebe’s architecture is likely the primary attribute driving native spider responses to these invasions. Differences in spider responses were attributable to differences in web construction behaviors relative to historic web substrate constraints. Orb-weavers in this system constructed webs between multiple plants, so they were limited by the overall quantity of native substrates but not by the architecture of individual native plant species. Irregular web-spiders built their webs within individual plants and were greatly constrained by the diminutive architecture of native plant substrates, so they were limited both by quantity and quality of native substrates. Evaluating native species traits in the context of invader-driven change can explain invasion outcomes and help to identify factors limiting native populations.

从理论层面而言，本土物种的功能性状应当决定其对入侵物种引发的环境变化的响应模式。为验证这一假说，我们利用死亡的斑点矢车菊（Centaurea stoebe）茎秆模拟大规模植物入侵，以探究本土蜘蛛的结网行为能否解释蜘蛛种群对C. stoebe入侵引发的生境结构变化的响应差异。两年后，与对照组样地相比，模拟入侵样地内的不规则结网蜘蛛丰度提升逾30倍，圆网蛛丰度提升逾23倍。此外，模拟入侵样地中的不规则结网蜘蛛所结的网面积扩大至原来的4.4倍，猎物捕获率提升至原来的5.0倍，进而使种群补充量提升逾2倍；圆网蛛的结网面积与猎物捕获率在两组处理间均无显著差异。不规则结网蜘蛛对模拟入侵的响应模式与自然入侵后的响应模式一致，证实C. stoebe的植株形态结构可能是驱动本土蜘蛛对该类入侵产生响应的核心因素。蜘蛛响应的差异可归因于其结网行为的差异，以及原有结网基质带来的限制约束：本系统中的圆网蛛会在多株植物之间结网，因此其受制约于本土基质的总数量，而非单个本土植物物种的形态结构；而不规则结网蜘蛛则会在单株植物内部结网，其结网行为受本土植物基质的小型形态结构强烈限制，因此同时受制约于本土基质的数量与质量。结合入侵物种驱动的环境变化背景评估本土物种的功能性状，能够阐释入侵结果，并有助于明确限制本土种群存续的关键因素。