Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota , 55108, USA.
Department of Plant Pathology, University of Minnesota, St. Paul, Minnesota, 55108, USA.
Ecology. 2018 Sep;99(9):1953-1963. doi: 10.1002/ecy.2389. Epub 2018 Aug 1.
Plants face a range of trade-offs as they attempt to maximize their fitness within a complex web composed of competitors, mutualists, and herbivores. In addition to growth-defense and competition-defense trade-offs, plants must balance their response to a wide range of potential enemies including pathogens and vertebrate and invertebrate herbivores. We tested for trade-offs in plant species' responses to different types of consumers using a foodweb manipulation experiment in which we selectively excluded large vertebrate herbivores and removed foliar fungi, soil fungi, and insects from natural and experimentally planted grassland communities. We found no evidence for trade-offs in the ability of plants to defend themselves against different sets of consumers, although plants varied widely in their responses to removal of different consumer groups. In addition, the species-level responses to consumer removal in monoculture were uncorrelated with each species' response in more diverse communities, highlighting the important role of local context (e.g., competition and apparent competition) in determining the effects of consumers. Plants must balance their allocation of energy among a wide variety of tasks including growing, competing for limited resources, and defending themselves against an array of potential enemies. We found that while plant species differed greatly in their response to the removal of consumers, species that were susceptible to the effects of one consumer group (e.g., insect herbivores) also were susceptible to other consumer groups (e.g., fungal pathogens). This suggests that plants differ in their overall allocation to defense, but defense investment can proffer protection against a wide array of natural enemies. We also found that plant responses to consumers depended on the diversity of the surrounding plant community, suggesting that among-plant interactions can alter their susceptibility to the impacts of consumers.
植物在复杂的竞争、共生和草食动物网络中，试图最大限度地提高自身适应性，这需要它们做出一系列权衡取舍。除了生长防御和竞争防御之间的权衡取舍外，植物还必须平衡其对包括病原体、脊椎动物和无脊椎动物草食动物在内的广泛潜在敌人的反应。我们使用食物网操纵实验来检验植物物种对不同类型消费者的反应是否存在权衡取舍，在该实验中，我们有选择地排除了大型脊椎动物草食动物，并从自然和实验种植的草地群落中去除了叶部真菌、土壤真菌和昆虫。我们没有发现植物在防御不同消费者组能力方面存在权衡取舍的证据，尽管植物对不同消费者群体去除的反应差异很大。此外，在单一种群中对消费者去除的种间反应与每种植物在更具多样性的群落中的反应无关，这突出了局部环境（例如竞争和显生竞争）在确定消费者效应中的重要作用。植物必须在各种任务（包括生长、争夺有限资源和防御潜在的各种敌人）之间平衡其能量分配。我们发现，尽管植物物种对消费者去除的反应差异很大，但对一组消费者（如昆虫草食动物）敏感的物种也对其他消费者群体（如真菌病原体）敏感。这表明植物在其整体防御分配上存在差异，但防御投资可以为它们提供对广泛的自然敌人的保护。我们还发现，植物对消费者的反应取决于周围植物群落的多样性，这表明植物间的相互作用可以改变它们对消费者影响的敏感性。
