Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, NY, USA.
Ecol Lett. 2013 Feb;16(2):252-60. doi: 10.1111/ele.12036. Epub 2012 Dec 6.
The cost of inbreeding (inbreeding depression, ID) is an important variable in the maintenance of reproductive variation. Ecological interactions such as herbivory could modulate this cost, provided that defence traits harbour deleterious mutations and herbivores are responsible for differences in fitness. In the field, we manipulated the presence of herbivores on experimentally inbred and outcrossed plants of Solanum carolinense (horsenettle) for three years. Damage was greater on inbred plants, and ID for growth and fitness was significantly greater under herbivory. Inbreeding reduced phenolic expression both qualitatively (phytochemical diversity) and quantitatively, indicating deleterious load at loci related to the biosynthesis of defence compounds. Our results indicate that inbreeding effects on plant-herbivore interactions are mediated by changes to functional plant metabolites, suggesting that variation in inbreeding could be a predictor of defence trait variation. The magnitude of herbivore-mediated, ecological ID indicates that herbivores could maintain outcrossing mating systems in nature.
近亲繁殖（近交衰退，ID）的成本是维持生殖变异的一个重要变量。生态相互作用，如食草，可以调节这种成本，前提是防御性状带有有害突变，并且食草动物负责适应度的差异。在野外，我们对实验中近交和杂交的卡罗莱纳茄（荨麻）进行了三年的食草动物存在的处理。在近亲繁殖的植物上，损伤更大，在食草动物的作用下，生长和适应性的 ID 显著更大。近交减少了酚类物质的表达，无论是在定性方面（植物化学多样性）还是定量方面，这表明与防御化合物生物合成相关的基因座存在有害负荷。我们的研究结果表明，近交对植物-食草动物相互作用的影响是通过改变植物功能代谢物来介导的，这表明近交的变异性可能是防御性状变异性的预测指标。食草动物介导的生态 ID 的幅度表明，食草动物可以在自然界中维持异交交配系统。
