Food body production in Macaranga triloba (Euphorbiaceae): a plant investment in anti-herbivore defence via symbiotic ant partners
Food body production in Macaranga triloba (Euphorbiaceae): a plant investment in anti-herbivore defence via symbiotic ant partners
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DOI：
10.2307/2960606
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发表时间：
1997-12-01
影响因子：
5.5
通讯作者：
Maschwitz, U
中科院分区：
文献类型：
--
作者：
Heil, M;Fiala, B;Maschwitz, U
1量化成本是评估任何植物性状净值所必需的第一步，特别是防御机制的成本在很大程度上是未知的。2东南亚重要的先锋树属Macaranga(大戟科)的几种树种都有中空的树干，里面有蚂蚁群体，作为一种‘生物’的反食草动物防御。在Macaranga三叶虫中，蚂蚁由下弯托叶背面产生的食物体(FBS)滋养。我们通过跟踪FB的生产来估计这种抗草食动物防御所产生的成本。3通过比较有蚂蚁进入和没有蚂蚁进入的偶数年龄托叶，在田间估计了36个不同大小的植物的FB产量。4 FB干物质产量约占不分枝幼树每日地上生物量的5%。如果将FB和叶片组织的化学成分考虑在内，这约占地上组织建造成本的9%。在能量方面，未分枝的树苗将其总同化量的0.6-5%投入到FB中。5 FB生产产生的反食草动物防御的相对投资随着植株规模的增加而双曲线下降。然而，FB产量与工厂规模之间存在线性关系。因此，尽管植物的相对投资随着规模的增加而减少，但为蚂蚁群体提供的食物供应不断增加。6第二项研究是为了调查共生蚂蚁的存在是否在数量上影响FB的生产。有蚂蚁栖息的植物产生的FBS是大小相似但没有蚂蚁的植物的35倍(平均8倍)。这种差异主要是由于无蚂蚁植株的托叶数量较少所致。7由于蚂蚁非常有效地保护它们的寄主植物，利用FBS滋养特定的互惠蚂蚁必须被认为是一种相当昂贵但却非常有益的反食草动物防御策略，但监管确保只有在蚂蚁存在的情况下才能保持FB的高产量。
1 Quantifying the costs is the first step necessary for assessing the net value of any plant trait, and the costs of defence mechanisms in particular are largely unknown.2 Several species of the important south-east Asian pioneer tree genus Macaranga (Euphorbiaceae) possess hollow stems that harbour ant colonies that act as a 'biotic' anti-herbivore defence. In Macaranga triloba, ants are nourished by food bodies (FBs) that are produced on the abaxial surfaces of recurved stipules. We estimated the costs arising from this kind of anti-herbivore defence by following FB production.3 FB production of 36 different-sized plants was estimated in the field by comparing even-aged stipules with and without access for ants.4 FB dry mass production amounted to about 5% of daily above-ground biomass production in unbranched saplings. When the chemical composition of FB and leaf tissue was taken into account, this represented about 9% of the above-ground tissue construction costs. In energetic terms, unbranched saplings invested 0.6-5% of their total assimilation in the FBs.5 The relative investment in anti-herbivore defence arising from FB production decreased hyperbolically with increasing plant size. However, a linear relationship was found between FB production and plant size. Thus, in spite of the plants' decreasing relative investment with increasing size, a continually increasing food supply was provided for the ant colonies.6 A second study was conducted to investigate whether FB production is influenced quantitatively by the presence of symbiotic ants. Ant-inhabited plants produced up to 35 times (mean 8 times) more FBs than similar-sized but ant-free ones. This difference resulted mainly from lower stipule numbers in ant-free plants. FB production of a whole plant therefore seems to be regulated to a high degree via stipule longevity.7 Since the ants protect their host-plant very effectively, nourishing specialized mutualistic ants by FBs must be considered a rather expensive, but nevertheless highly beneficial, strategy of anti-herbivore defence, but regulation ensures that FB production is maintained at high rates only when ants are present.