Díaz Mario, Pulido Fernando J, Møller Anders P
Departamento de Ciencias Ambientales, Facultad de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, 45071, Toledo, Spain.
Oecologia. 2004 Apr;139(2):224-34. doi: 10.1007/s00442-004-1491-9. Epub 2004 Feb 13.
Plants are able to compensate for loss of tissue due to herbivores at a variety of spatial and temporal scales, masking detrimental effects of herbivory on plant fitness at these scales. The stressing effect of herbivory could also produce instability in the development of plant modules, and measures of such instability may reflect the fitness consequences of herbivory if instability is related to components of plant fitness. We analyse the relationships between herbivory, developmental instability and production of female flowers and fruits of holm oak Quercus ilex trees by means of herbivore removal experiments. Removal of leaf herbivores reduced herbivory rates at the tree level, but had no effect on mean production of female flowers or mature fruits, whereas herbivory tended to enhance flower production and had no effect on fruit abortion at the shoot level. Differences in herbivory levels between shoots of the same branch did not affect the size and fluctuating asymmetry of intact leaves. These results indicate compensation for herbivory at the tree level and over-compensation at the shoot level in terms of allocation of resources to female flower production. Removal of insect herbivores produced an increase in the mean developmental instability of leaves at the tree level in the year following the insecticide treatment, and there was a direct relationship between herbivory rates in the current year and leaf fluctuating asymmetry the following year irrespective of herbivore removal treatment. Finally, the production of pistillate flowers and fruits by trees was inversely related to the mean fluctuating asymmetry of leaves growing the same year. Leaf fluctuating asymmetry was thus an estimator of the stressing effects of herbivory on adult trees, an effect that was delayed to the following year. As leaf fluctuating asymmetry was also related to tree fecundity, asymmetry levels provided a sensitive measure of plant performance under conditions of compensatory responses to herbivory.
植物能够在各种空间和时间尺度上补偿因食草动物造成的组织损失，掩盖了食草作用在这些尺度上对植物适合度的有害影响。食草作用的胁迫效应也可能导致植物模块发育的不稳定，如果这种不稳定与植物适合度的组成部分相关，那么对这种不稳定的测量可能反映食草作用对适合度的影响。我们通过去除食草动物的实验，分析了食草作用、发育不稳定性与圣栎（Quercus ilex）树雌花和果实产量之间的关系。去除叶片食草动物降低了树木水平上的食草率，但对雌花或成熟果实的平均产量没有影响，而在枝条水平上，食草作用倾向于增加花的产量，对果实败育没有影响。同一枝条不同嫩枝间食草水平的差异并不影响完整叶片的大小和波动不对称性。这些结果表明，在树木水平上对食草作用有补偿，而在枝条水平上，就资源分配到雌花生产而言存在超补偿。在杀虫剂处理后的一年，去除昆虫食草动物导致树木水平上叶片的平均发育不稳定性增加，并且无论是否进行食草动物去除处理，当年的食草率与次年叶片的波动不对称性之间存在直接关系。最后，树木的雌花和果实产量与同一年生长叶片的平均波动不对称性呈负相关。因此，叶片波动不对称性是食草作用对成年树木胁迫效应的一个指标，这种效应会延迟到次年。由于叶片波动不对称性也与树木的繁殖力相关，不对称水平提供了在对食草作用的补偿反应条件下植物表现的一个敏感指标。
