Bioenergy landscapes drive trophic shifts in generalist ants
Bioenergy landscapes drive trophic shifts in generalist ants
复制标题
生物能源景观驱动多面蚂蚁的营养变化
DOI：
10.1111/1365-2656.13407
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发表时间：
2020
影响因子：
4.8
通讯作者：
Shik, ed., Jonathan Zvi
中科院分区：
文献类型：
--
作者：
Helms, IV, Jackson A.;Roeder, Karl A.;Ijelu, Selassie E.;Ratcliff, Ian;Haddad, Nick M.;Shik, ed., Jonathan Zvi
营养生态位的变化是生物体获得能量和营养的途径，是生物体对环境条件做出反应的基本方式。但是，物种改变其营养生态位以应对全球变化的能力，以及它们在可能的情况下这样做的方式，在这里，我们通过三个长期和大规模的实验来研究食物网，以测试资源可用性和营养需求如何相互作用，以确定生物体在全球土地利用最大趋势之一的背景下的营养生态位-我们使用碳和氮稳定同位素分析来表征三种生物燃料作物的节肢动物食物网，这些作物代表了植物资源丰富度的梯度（玉米单作，以原生柳枝稷为主的田地和恢复的草原），并量化一种广泛分布的通才蚂蚁物种在不同生境中的营养生态位变化。在此过程中，我们测量的基础资源丰富度的影响，食物链的长度，生态位宽度和营养位置。我们的研究结果在两个假设的背景下，解释营养生态位的变化-生态位变化假说，强调资源多样性和生态机会的重要性，和最佳饮食假说，强调饮食的限制和最佳资源的可用性。增加植物丰富度延长食物链的10%-20%相比，单作。多面手蚂蚁的生态位宽度并不随资源丰富度而变化，这表明它们受到最佳饮食需求和约束的限制，而不是受到生态机会的限制。相反，蚂蚁通过改变它们估计的营养位置来应对植物丰富度的变化。在资源贫乏的单一栽培中，蚂蚁是顶级捕食者，与捕食性蜘蛛共享营养地位。相反，在资源丰富的环境中，蚂蚁是杂食动物，依赖于动物猎物和植物资源的混合。除了强调替代生物能源景观对生态系统的新影响外，我们的研究结果表明，生态位宽度和营养多样化更多地取决于最佳资源的存在，而不仅仅是生态机会。
Changes in trophic niche—the pathways through which an organism obtains energy and nutrients—are a fundamental way in which organisms respond to environmental conditions. But the capacity for species to alter their trophic niches in response to global change, and the ways they do so when able, remain largely unknown.Here we examine food webs in three long‐term and large‐scale experiments to test how resource availability and nutritional requirements interact to determine an organism's trophic niche in the context of one of the largest global trends in land use—the rise in bioenergy production.We use carbon and nitrogen stable isotope analyses to characterize arthropod food webs across three biofuel crops representing a gradient in plant resource richness (corn monocultures, fields dominated by native switchgrass and restored prairie), and to quantify changes in the trophic niche of a widespread generalist ant species across habitats. In doing so, we measure the effects of basal resource richness on food chain length, niche breadth and trophic position. We frame our results in the context of two hypotheses that explain variation in trophic niche—the niche variation hypothesis which emphasizes the importance of resource diversity and ecological opportunity, and the optimal diet hypothesis which emphasizes dietary constraints and the availability of optimal resources.Increasing plant richness lengthened food chains by 10%–20% compared to monocultures. Niche breadths of generalist ants did not vary with resource richness, suggesting they were limited by optimal diet requirements and constraints rather than by ecological opportunity. The ants instead responded to changes in plant richness by shifting their estimated trophic position. In resource‐poor monocultures, the ants were top predators, sharing a trophic position with predatory spiders. In resource‐rich environments, in contrast, the ants were omnivores, relying on a mix of animal prey and plant‐based resources.In addition to highlighting novel ecosystem impacts of alternate bioenergy landscapes, our results suggest that niche breadth and trophic diversification depend more on the presence of optimal resources than on ecological opportunity alone.