植物界的＂变色龙＂

神探福尔摩斯需要出场了。人们发现了一个新的伪装大师，而且它是一种植物。伪装和模仿通常出现在动物王国里。鹰蛾毛虫通过扮成蛇将捕食者吓走。蚁蛛属的跳蛛在爬向毫无防备的昆虫时会模仿蚂蚁，同时准备好自己的尖牙。植物中很少存在模仿或者保护色的例子。澳大利亚的一些槲寄生物种仅能模仿一个其他物种。不过对木本滕蔓Boquila trifoliolata来说，事实并非如此，它会通过叶子变化复制各种宿主树木。

B. Trifoliolata原产于智利和阿根廷，是显示出可模仿一些宿主的第一种植物。根据4月24日发表在《当代生物学》杂志上的研究，这是一种罕见的特性，被称为“模仿多态”，以前仅在蝴蝶中发现过。当B. Trifoliolata的藤蔓延伸到树木分枝上时，其多变的叶子可以改变大小、形状、颜色、朝向甚至静脉模式，以匹配周围的树叶。如果藤蔓跨越到另一棵树上，它就会发生变化，即使新宿主的叶子大小是原来的10倍而且形状截然不同。

据研究人员解释，这种伪装是一种防御诸如象鼻虫、金花虫等食草昆虫的措施。他们将挂在树枝上伪装的藤叶和仍留在土地上寻找树木，以及攀爬在无叶树干上的藤叶进行了比较。结果显示，地上和树干上藤叶的被食概率分别增加了33%和100%。

目前尚不清楚B. Trifoliolata如何识别树木种类并相应地进行变化。研究人员称，藤蔓也许能读出藏在气味或者树木分泌的化学物质中的线索，或者存在微生物能传递伪装藤蔓和宿主树木之间的基因激活信号。

原文摘要：

Leaf Mimicry in a Climbing Plant Protects against Herbivory

Ernesto Gianoli, FeRNAndo CarrASCo-Urra

Mimicry refers to adaptive similarity between a mimic organism and a model. Mimicry in animals is rather common, whereas documented cases in plants are rare, and the associated benefits are seldom elucidated [1, 2]. We show the occurrence of leaf mimicry in a climbing plant endemic to a temperate rainforest. The woody vine Boquila trifoliolata mimics the leaves of its supporting trees in terms of size, shape, color, orientation, petiole length, and/or tip spininess. Moreover, sequential leaf mimicry occurs when a single individual vine is associated with different tree species. Leaves of unsupported vines differed from leaves of climbing plants closely associated with tree foliage but did not differ from those of vines climbing onto leafless trunks. Consistent with an herbivory-avoidance hypothesis, leaf herbivory on unsupported vines was greater than that on vines climbing on trees but was greatest on vines climbing onto leafless trunks. Thus, B. trifoliolatagains protection against herbivory not merely by climbing and thus avoiding ground herbivores [3] but also by climbing onto trees whose leaves are mimicked. Unlike earlier cases of plant mimicry or crypsis, in which the plant roughly resembles a background or color pattern [4–7] or mimics a single host [8, 9],B. trifoliolata is able to mimic several hosts.

标签: 木本滕蔓 槲寄生物种 宿主树木

作者：张冬冬