Evolutionary ecology of Datura stramonium:: Genetic variation and costs for tolerance to defoliation
Evolutionary ecology of Datura stramonium:: Genetic variation and costs for tolerance to defoliation
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DOI：
10.1111/j.0014-3820.2000.tb00080.x
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发表时间：
2000-06-01
期刊：
影响因子：
3.3
通讯作者：
Núnez-Farfán, J
中科院分区：
文献类型：
--
作者：
Fornoni, J;Núnez-Farfán, J
将植物受损后的耐受性纳入作为应对草食动物的新替代方案（而不是抵抗力），为我们理解植物和食草动物之间的共同进化开辟了新途径。尽管在某些物种中发现了耐落叶的遗传变异，但对非农业物种的研究却很少。在这项研究中，我们探讨了一年生杂草曼陀罗是否存在耐受性遗传变异以及耐受性的适应成本。为了确定哪种适应性相关性状可能导致耐受性差异，记录了生长速率、花和果实总产量以及每个果实的种子数量。来自墨西哥城种群的 D. stramium 近交系复制品暴露于四种落叶水平（0%、10%、30% 和 70%）。我们使用受控遗传材料（自交系）进行的温室实验结果表明，在落叶环境中检测到了显着的耐受性遗传变异。在最高程度的落叶中，落叶使植物的适应性从 15% 降低到 25%。自交系之间耐受性的差异是由于成熟果实比例在落叶水平上的差异性减少（最多 20%）造成的。在落叶水平内，植物适应性的显着遗传变异表明可以选择耐受性。两种环境（有和没有损伤）中自交系的适应度值之间的相关性为正（r(g) = 0.77），但不显着，表明不存在耐受性的适应度成本。耐受性遗传变异的发现可能是由于自交系之间通过补偿克服叶损伤的能力的差异，或者是由于诱导次生代谢物产生的成本。我们的结果表明在食草压力梯度下选择反应规范的可能性，并强调了在寻找耐受性遗传变异的潜在原因时剖析由补偿反应引起的重要性。
The incorporation of plant tolerance after damage as a new alternative to cope with herbivory, as opposed to resistance, opened new avenues for our understanding of coevolution between plants and herbivores. Although genetic variation on tolerance to defoliation has been detected in some species, few studies have been undertaken with nonagricultural species. In this study, we explore in the annual weed Datura stramonium the existence of genetic variation for tolerance and fitness costs of tolerance. To determine which fitness-related trait was responsible for possible differences in tolerance, growth rate, total flower and fruit production, and the number of seeds per fruit were recorded. Inbred line replicates of D. stramonium from a population of Mexico City were exposed to four defoliation levels (0%, 10%, 30%, and 70%). Our results from a greenhouse experiment using controlled genetic material (inbred lines) indicated that significant genetic variation for tolerance was detected across defoliation environments. Defoliation reduced plant fitness from 15% to 25% in the highest levels of defoliation. Differences on tolerance among inbred lines were accounted by a differential reduction in the proportion of matured fruits across defoliation levels (up to 20%). Within defoliation levels, significant genetic variation in plant fitness suggests that tolerance could be selected. The correlation between fitness values of inbred lines in two environments (with and without damage) was positive (r(g) = 0.77), but not significant, suggesting absence of fitness costs for tolerance. The finding of genetic variation on tolerance might be either due to differences among inbred lines in their capability to overcome foliar damage through compensation or due to costs incurred by inducing secondary metabolites. Our results indicate the potential for norms of reaction to be selected under a gradient of herbivory pressure and highlights the importance of dissecting induced from compensatory responses when searching for potential causes of genetic variation on tolerance.