Phylogenetic escalation and decline of plant defense strategies
Phylogenetic escalation and decline of plant defense strategies
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DOI：
10.1073/pnas.0802368105
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发表时间：
2008-07-22
影响因子：
11.1
通讯作者：
Fishbein, Mark
中科院分区：
文献类型：
--
作者：
Agrawal, Anurag A.;Fishbein, Mark
作为大多数食物网的基础资源，植物已经进化出无数的策略来对抗食草动物的消耗。在过去的 50 年里，植物防御理论被用来解释次级化学和其他防御性状的丰度、分布和多样性的显着变化。例如，敌人驱动的进化动力学的经典理论假设防御特征通过多样化过程而升级。尽管宏观进化模式是防御理论的明确组成部分，但以前从未尝试过系统发育分析来理清有关以下方面的具体预测：(t) 抗性性状的投资，(b) 损害后的恢复，以及 (iii) 植物生长率。我们构建了 38 种马利筋的分子系统发育，并使用最大似然方法测试了防御理论的四个主要预测。我们没有找到对增长率假设的支持。我们的主要发现是三种最有效的抗性性状（心内酯、乳胶和毛状体）的系统衰退模式以及再生能力的增强。我们的新生物学方法补充了更常见的古生物学方法，以发现生命进化的方向趋势，并指出天敌在物种宏观进化中的重要性。宏观进化再生能力不断增强和抵抗力下降的发现为了解植物和食草动物之间正在进行的共同进化动态提供了一个窗口，并建议对经典植物防御理论进行修订。当植物主要被专门的食草动物消耗时，在多样化过程中，再生（或耐受性）可能比抗性性状更受青睐。
As the basal resource in most food webs, plants have evolved myriad strategies to battle consumption by herbivores. Over the past 50 years, plant defense theories have been formulated to explain the remarkable variation in abundance, distribution, and diversity of secondary chemistry and other defensive traits. For example, classic theories of enemy-driven evolutionary dynamics have hypothesized that defensive traits escalate through the diversification process. Despite the fact that macroevolutionary patterns are an explicit part of defense theories, phylogenetic analyses have not been previously attempted to disentangle specific predictions concerning (t) investment in resistance traits, (b) recovery after damage, and (iii) plant growth rate. We constructed a molecular phylogeny of 38 species of milkweed and tested four major predictions of defense theory using maximum-likelihood methods. We did not find support for the growth-rate hypothesis. Our key finding was a pattern of phyletic decline in the three most potent resistance traits (cardenolides, latex, and trichomes) and an escalation of regrowth ability. Our neontological approach complements more common paleontological approaches to discover directional trends in the evolution of life and points to the importance of natural enemies in the macroevolution of species. The finding of macroevolutionary escalating regowth ability and declining resistance provides a window into the ongoing coevolutionary dynamics between plants and herbivores and suggests a revision of classic plant defense theory. Where plants are primarily consumed by specialist herbivores, regrowth (or tolerance) may be favored over resistance traits during the diversification process.