Department of Biology, William & Mary, 540 Landrum Drive, Williamsburg, VA, 23185, USA.
Departments of Entomology and Forestry and Natural Resources, Purdue University, 170 S. University Street, West Lafayette, IN, 47907, USA.
Am J Bot. 2021 Mar;108(3):388-401. doi: 10.1002/ajb2.1630.
Leaf economic spectrum (LES) theory has historically been employed to inform vegetation models of ecosystem processes, but largely neglects intraspecific variation and biotic interactions. We attempt to integrate across environment-plant trait-herbivore interactions within a species at a range-wide scale.
We measured traits in 53 populations spanning the range of common milkweed (Asclepias syriaca) and used a common garden to determine the role of environment in driving patterns of intraspecific variation. We used a feeding trial to determine the role of plant traits in monarch (Danaus plexippus) larval development.
Trait-trait relationships largely followed interspecific patterns in LES theory and persisted in a common garden when individual traits change. Common milkweed showed intraspecific variation and biogeographic clines in traits. Clines did not persist in a common garden. Larvae ate more and grew larger when fed plants with more nitrogen. A longitudinal environmental gradient in precipitation corresponded to a resource gradient in plant nitrogen, which produces a gradient in larval performance.
Biogeographic patterns in common milkweed traits can sometimes be predicted from LES, are largely driven by environmental conditions, and have consequences for monarch larval performance. Changes to nutrient dynamics of landscapes with common milkweed could potentially influence monarch population dynamics. We show how biogeographic trends in intraspecific variation can influence key ecological interactions, especially in common species with large distributions.
叶片经济谱 (LES) 理论历史上被用于为生态系统过程的植被模型提供信息，但在很大程度上忽略了种内变异和生物相互作用。我们试图在一个物种的范围内广泛整合环境-植物特征-食草动物相互作用。
我们在跨越普通乳草 (Asclepias syriaca) 分布范围的 53 个种群中测量了特征，并使用一个共同的花园来确定环境在驱动种内变异模式中的作用。我们使用饲养试验来确定植物特征在帝王蝶 (Danaus plexippus) 幼虫发育中的作用。
特征-特征关系在 LES 理论中很大程度上遵循种间模式，并在个体特征发生变化时在共同花园中持续存在。普通乳草在特征上表现出种内变异和生物地理渐变。在共同花园中，渐变并没有持续存在。幼虫吃更多含氮量高的植物，生长得更大。降水的纵向环境梯度与植物氮的资源梯度相对应，这会产生幼虫表现的梯度。
普通乳草特征的生物地理模式有时可以从 LES 预测，主要由环境条件驱动，并对帝王蝶幼虫的表现产生影响。具有普通乳草的景观养分动态的变化可能会影响帝王蝶的种群动态。我们展示了种内变异的生物地理趋势如何影响关键的生态相互作用，特别是在分布广泛的常见物种中。
