Department of Biological Sciences, Louisiana State University, 202 Louisiana State University Life Sciences Building, Baton Rouge, Louisiana, 70803, USA.
Department of Ecology and Evolutionary Biology and School of Natural Resources and Environment, University of Michigan, 2053 Natural Sciences Building, 830 North University, Ann Arbor, Michigan, 48109-1048, USA.
Ecology. 2018 May;99(5):1031-1038. doi: 10.1002/ecy.2198. Epub 2018 Apr 4.
While it is well established that climate change affects species distributions and abundances, the impacts of climate change on species interactions has not been extensively studied. This is particularly important for specialists whose interactions are tightly linked, such as between the monarch butterfly (Danaus plexippus) and the plant genus Asclepias, on which it depends. We used open-top chambers (OTCs) to increase temperatures in experimental plots and placed either nonnative Asclepias curassavica or native A. incarnata in each plot along with monarch larvae. We found, under current climatic conditions, adult monarchs had higher survival and mass when feeding on A. curassavica. However, under future conditions, monarchs fared much worse on A. curassavica. The decrease in adult survival and mass was associated with increasing cardenolide concentrations under warmer temperatures. Increased temperatures alone reduced monarch forewing length. Cardenolide concentrations in A. curassavica may have transitioned from beneficial to detrimental as temperature increased. Thus, the increasing cardenolide concentrations may have pushed the larvae over a tipping point into an ecological trap; whereby past environmental cues associated with increased fitness give misleading information. Given the ubiquity of specialist plant-herbivore interactions, the potential for such ecological traps to emerge as temperatures increase may have far-reaching consequences.
虽然气候变化影响物种分布和丰度已经得到充分证实，但气候变化对物种相互作用的影响尚未得到广泛研究。对于那些相互作用紧密相关的专家来说，这一点尤为重要，例如依赖于乳草属植物的黑脉金斑蝶（Danaus plexippus）与其之间的关系。我们使用开顶式气室（OTCs）来提高实验区域的温度，并在每个区域内放置非本地的乳草属植物（如 A. curassavica）或本地的 A. incarnata，同时在这些植物上放置黑脉金斑蝶幼虫。我们发现，在当前的气候条件下，黑脉金斑蝶成虫在食用 A. curassavica 时的存活率和体重更高。然而，在未来的条件下，黑脉金斑蝶在 A. curassavica 上的生存状况要差得多。随着温度的升高，成年黑脉金斑蝶的存活率和体重下降与 cardenolide 浓度的增加有关。仅温度升高就会降低黑脉金斑蝶的前翅长度。乳草属植物 A. curassavica 中的 cardenolide 浓度可能随着温度的升高从有益转变为有害。因此，幼虫可能已经越过了一个生态陷阱的临界点；即与增加适应性相关的过去环境线索提供了误导性信息。鉴于专门的植物-食草动物相互作用的普遍性，随着温度的升高，这种生态陷阱出现的可能性可能会产生深远的影响。
