Kharouba Heather M, Vellend Mark, Sarfraz Rana M, Myers Judith H
The Biodiversity Research Centre, University of British Columbia, 2212 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
Center for Population Biology, University of California at Davis, One Shields Avenue, Davis, CA, 95616, USA.
J Anim Ecol. 2015 May;84(3):785-796. doi: 10.1111/1365-2656.12328. Epub 2015 Jan 9.
The phenology of many species is shifting in response to climatic changes, and these shifts are occurring at varying rates across species. This can potentially affect species' interactions and individual fitness. However, few studies have experimentally tested the influence of warming on the timing of species interactions. This is an important gap in the literature given the potential for different direct and indirect effects of temperature via phenological change. Our aim was to test the effects of warming on the western tent caterpillar (Malacosoma californicum pluviale). In addition to the direct effects of warming, we considered the two primary indirect effects mediated by warming-driven changes in its host plant, red alder (Alnus rubra): changes in resource availability due to phenological mismatch (i.e. changes in the relative timing of the interaction), and changes in resource quality associated with leaf maturation. We experimentally warmed egg masses and larvae of the western tent caterpillar placed on branches of red alder in the field. Warming advanced the timing of larval but not leaf emergence. This led to varying degrees of phenological mismatch, with larvae emerging as much as 25 days before to 10 days after the emergence of leaves. Even the earliest-emerging larvae, however, had high survival in the absence of leaves for up to 3 weeks, and they were surprisingly resistant to starvation. In addition, although warming created phenological mismatch that initially slowed the development of larvae that emerged before leaf emergence, it accelerated larval development once leaves were available. Therefore, warming had no net effect on our measures of insect performance. Our results demonstrate that the indirect effects of warming, in creating phenological mismatch, are as important to consider as the direct effects on insect performance. Although future climatic warming might influence plants and insects in different ways, some insects may be well adapted to variation in the timing of their interactions.
许多物种的物候正在因气候变化而发生变化，且这些变化在不同物种间的速率各异。这可能会影响物种间的相互作用以及个体的适应性。然而，很少有研究通过实验测试变暖对物种相互作用时间的影响。鉴于温度通过物候变化可能产生不同的直接和间接影响，这是文献中的一个重要空白。我们的目标是测试变暖对西部天幕毛虫（Malacosoma californicum pluviale）的影响。除了变暖的直接影响外，我们还考虑了由变暖驱动的其寄主植物红桤木（Alnus rubra）变化所介导的两个主要间接影响：由于物候不匹配导致的资源可用性变化（即相互作用的相对时间变化），以及与叶片成熟相关的资源质量变化。我们在野外对放置在红桤木枝条上的西部天幕毛虫的卵块和幼虫进行了实验性升温处理。升温提前了幼虫出现的时间，但没有提前叶片出现的时间。这导致了不同程度的物候不匹配，幼虫在叶片出现前多达25天至叶片出现后10天出现。然而，即使是最早出现的幼虫，在没有叶片的情况下存活长达3周，并且它们对饥饿具有惊人的抵抗力。此外，尽管升温造成了物候不匹配，最初减缓了在叶片出现之前出现的幼虫的发育，但一旦有叶片，它就加速了幼虫的发育。因此，升温对我们衡量昆虫表现的指标没有净影响。我们的结果表明，变暖在造成物候不匹配方面的间接影响，与对昆虫表现的直接影响一样重要，值得考虑。尽管未来的气候变暖可能以不同方式影响植物和昆虫，但一些昆虫可能很好地适应了它们相互作用时间的变化。
