Sources of variation in foliar secondary chemistry in a tropical forest tree community
Sources of variation in foliar secondary chemistry in a tropical forest tree community
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DOI：
10.1002/ecy.1689
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发表时间：
2017-03-01
期刊：
影响因子：
4.8
通讯作者：
Wright, S. Joseph
中科院分区：
文献类型：
--
作者：
Sedio, Brian E.;Echeverri, Juan C. Rojas;Wright, S. Joseph
专业食草动物和病原菌可以在寄主之间诱导负的同种密度依赖，从而促进植物群落的多样性。少数高度多样化的属构成了热带森林中树木多样性的很大一部分。这些密切相关的同系物很可能是共同的天敌。多样化的防御仍然可以允许同系人划分由天敌定义的生态位空间，但种间防御的差异必须超过种内防御的差异。我们询问次生化学的种间变异是否超过来自四个高度多样化的热带乔木属物种的种内变异。我们使用新的方法来量化叶组织甲醇提取物中存在的所有化合物的化学结构相似性。我们试图通过选择来自不同个体发育阶段(膨大的未成熟与完全硬化的成熟)、不同的光照环境(深层下阴凉与大的林隙)和不同季节(干燥与潮湿)的同种叶片来最大化种内差异。化学结构相似性因个体发育、光照环境、季节不同而异，但种间差异较大，包括同属种间差异较大。我们的结果表明，次生化学中的物种差异相对于种内差异是很大的，也许足够大，以允许基于化学防御的同类树种之间的生态位分离。
Specialist herbivores and pathogens could induce negative conspecific density dependence among their hosts and thereby contribute to the diversity of plant communities. A small number of hyperdiverse genera comprise a large portion of tree diversity in tropical forests. These closely related congeners are likely to share natural enemies. Diverse defenses could still allow congeners to partition niche space defined by natural enemies, but interspecific differences in defenses would have to exceed intraspecific variation in defenses. We ask whether interspecific variation in secondary chemistry exceeds intraspecific variation for species from four hyperdiverse tropical tree genera. We used novel methods to quantify chemical structural similarity for all compounds present in methanol extracts of leaf tissue. We sought to maximize intraspecific variation by selecting conspecific leaves from different ontogenetic stages (expanding immature vs. fully hardened mature), different light environments (deep under-story shade vs. large forest gaps), and different seasons (dry vs. wet). Chemical structural similarity differed with ontogeny, light environment, and season, but interspecific differences including those among congeneric species were much larger. Our results suggest that species differences in secondary chemistry are large relative to within-species variation, perhaps sufficiently large to permit niche segregation among congeneric tree species based on chemical defenses.