Growth-defense tradeoffs shape the genetic composition of aspen forests

All organisms experience fundamental conflicts between divergent metabolic processes. In plants, a pivotal conflict occurs between allocation to growth, which accelerates resource acquisition, and to defense, which protects existing tissue against herbivory. Tradeoffs between growth and defense traits are not universally observed, and a fundamental prediction of plant evolutionary ecology is that context-dependence of these tradeoffs contributes to the maintenance of intraspecific variation in defense. This prediction has rarely been tested, however, and the evolutionary consequences of growth-defense tradeoffs in different environments are poorly understood. Here we show that intraspecific trait tradeoffs interact with competitive environment to drive natural selection of tree genotypes corresponding to their growth-defense phenotypes. Our results show for the first time that a functional trait tradeoff, when coupled with environmental variation, causes real-time divergence in the gene...

所有生物都会在不同代谢过程之间面临根本性冲突。在植物中，一类核心冲突出现在生长资源分配与防御资源分配之间：前者可加快资源获取速率，后者则保护现有组织免受植食性生物危害。生长与防御性状间的权衡并非普遍存在，而植物进化生态学的一项核心预测认为，这类权衡的情境依赖性是维持防御相关种内变异的关键因素。然而，该预测极少得到实证检验，且不同环境下生长-防御权衡的进化后果仍鲜为人知。本研究表明，种内性状权衡与竞争环境相互作用，可依据树木的生长-防御表型驱动其基因型的自然选择。本研究结果首次证实，功能性状权衡与环境变异共同作用，可引发基因层面的实时分化……