Adaptive significance and ontogenetic variability of the waxy zone in Nepenthes rafflesiana
Adaptive significance and ontogenetic variability of the waxy zone in Nepenthes rafflesiana
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DOI：
10.1093/aob/mcp238
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发表时间：
2009-12-01
期刊：
影响因子：
4.2
通讯作者：
Di Giusto, Bruno
中科院分区：
文献类型：
--
作者：
Gaume, Laurence;Di Giusto, Bruno
在猪笼草的上部的光滑的蜡质区长期以来一直被认为是肉食性植物的关键诱捕结构;然而，据报道，蜡的存在是可变的物种内和物种之间的这个物种丰富的属。本研究提出的问题的适应意义的蜡质区，并调查的基础上，其变异性和相关性的个体发育原因与投手should.In文莱（婆罗洲）的整个植物个体发育的蜡质区的表达进行了研究，在两个类群的猪笼草rafflesiana复杂的，typica和elongata，不同的投手的形状和大小。我们还通过比较含蜡和不含蜡植物的诱捕效率和捕获的猎物数量来检验这一区域的适应意义。在elongata中，蜡质区总是很好地扩展，并且细长的捕虫笼在植物发育过程中的形状变化很小。蜡能有效地诱捕实验蚂蚁，但捕到的猎物数量很少。与此相反，在typica中，蜡质区在连续生产的投手中减少，直到它在植物的幼年期结束时消失。因此，在植物个体发育的整个过程中，壶状体的形状不断变化，从细长到卵形。在典型猪笼草中，捕获的猎物数量更多，但与消化液相比，蜡质在诱捕中的作用较小，并且蜡质植物与非蜡质植物相比并没有表现出更高的昆虫滞留和猎物丰度。蜡质区并不总是猪笼草中的关键诱捕结构，当被更有效的特征取代时，蜡质区可能会丢失。这项研究指出了猪笼草的结构是如何被选择的，以及发育机制的进化变化可能在猪笼草的形态多样性中发挥作用。
The slippery waxy zone in the upper part of pitchers has long been considered the key trapping structure of the Nepenthes carnivorous plants; however, the presence of wax is reported to be variable within and between species of this species-rich genus. This study raises the question of the adaptive significance of the waxy zone and investigates the basis for an ontogenetic cause of its variability and correlation with pitcher shape.In Brunei (Borneo) the expression of the waxy zone throughout plant ontogeny was studied in two taxa of the Nepenthes rafflesiana complex, typica and elongata, which differ in pitcher shape and size. We also tested the adaptive significance of this zone by comparing the trapping efficiency and the number of prey captured of wax-bearing and wax-lacking plants.In elongata, the waxy zone is always well expanded and the elongated pitchers change little in form during plant development. Wax efficiently traps experimental ants but the number of captured prey in pitchers is low. In contrast, in typica, the waxy zone is reduced in successively produced pitchers until it is lost at the end of the plant's juvenile stage. The form of pitchers thus changes continuously throughout plant ontogeny, from elongated to ovoid. In typica, the number of captured prey is greater, but the role of wax in trapping is minor compared with that of the digestive liquid, and waxy plants do not show a higher insect retention and prey abundance as compared with non-waxy plants.The waxy zone is not always a key trapping structure in Nepenthes and can be lost when supplanted by more efficient features. This study points out how pitcher structure is submitted to selection, and that evolutionary changes in developmental mechanisms could play a role in the morphological diversity of Nepenthes.