表型可塑性与外来植物的入侵能力

Phenotypic plasticity and invasiveness of alien plants

外来植物的入侵能力与其性状之间的关系是入侵生态学中的基本问题之一。成功的入侵种常常能占据多样化的生境 ,并以广幅的环境耐受性为特征。遗传分化 (包括生态型分化 )和表型可塑性是广布性物种适应变化、异质性生境的两种不同但并不矛盾和排斥的策略。越来越多的实验证据表明 ,表型可塑性具有确定的遗传基础 ,本身是一种可以独立进化的性状。许多入侵种遗传多样性比较低 ,但同时又占据了广阔的地理分布区和多样化的生境 ,表型可塑性可能在这些物种的入侵成功和随后的扩散中起到了关键作用。本文首先介绍表型可塑性的含义 ,简述表型可塑性和生物适应的关系 ,然后从理论分析和实验证据两个方面论述了表型可塑性与外来植物入侵能力的相关性 ,最后针对进一步的研究工作进行了讨论。当然 ,并非所有入侵种的成功都能归因于表型可塑性 ,作者认为对于那些遗传多样性比较低同时又占据多样化生境的入侵种 ,表型可塑性和入侵能力的正相关可能是一条普遍法则 。

How the traits of invasive plants determine their invasiveness is one of the major issues in invasion biology. Invasive plants usually have broad ecological amplitudes, and hence can exploit a great diversity of habitats. Genetic differentiation and phenotypic plasticity are two major strategies that invasive plants can use to invade broad geographical areas and diverse ecosystems. Phenotypic plasticity is a trait that has a certain genetic basis and can evolve independently. Although some of the invasive plants have low genetic variation, they can still invade diverse habitats. Phenotypic plasticity may play a critical role in invasion of these species into new environments. In this review, the concept of phenotypic plasticity and its significance for adaptation were introduced. The relationship between phenotypic plasticity and the invasiveness of alien plants was discussed, supported by theoretical analysis and published experimental evidence. We also suggest some issues that might be addressed in future studies for better understanding of the mechanisms of successful invasion with reference to phenotypic plasticity. Although successful invasion cannot be explained by phenotypic plasticity alone, the positive correlation between invasiveness and phenotypic plasticity seems to be a rule rather than an exception for those invasive species with low genetic diversity but a broad geographic distribution.