Centre for Invasion Biology, Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa.
Ann Bot. 2012 Jan;109(1):19-45. doi: 10.1093/aob/mcr277. Epub 2011 Oct 31.
Biological invasions are a major ecological and socio-economic problem in many parts of the world. Despite an explosion of research in recent decades, much remains to be understood about why some species become invasive whereas others do not. Recently, polyploidy (whole genome duplication) has been proposed as an important determinant of invasiveness in plants. Genome duplication has played a major role in plant evolution and can drastically alter a plant's genetic make-up, morphology, physiology and ecology within only one or a few generations. This may allow some polyploids to succeed in strongly fluctuating environments and/or effectively colonize new habitats and, thus, increase their potential to be invasive.
We synthesize current knowledge on the importance of polyploidy for the invasion (i.e. spread) of introduced plants. We first aim to elucidate general mechanisms that are involved in the success of polyploid plants and translate this to that of plant invaders. Secondly, we provide an overview of ploidal levels in selected invasive alien plants and explain how ploidy might have contributed to their success.
Polyploidy can be an important factor in species invasion success through a combination of (1) 'pre-adaptation', whereby polyploid lineages are predisposed to conditions in the new range and, therefore, have higher survival rates and fitness in the earliest establishment phase; and (2) the possibility for subsequent adaptation due to a larger genetic diversity that may assist the 'evolution of invasiveness'. Alternatively, polyploidization may play an important role by (3) restoring sexual reproduction following hybridization or, conversely, (4) asexual reproduction in the absence of suitable mates. We, therefore, encourage invasion biologists to incorporate assessments of ploidy in their studies of invasive alien species.
生物入侵是世界许多地区的一个主要生态和社会经济问题。尽管近几十年来研究呈爆炸式增长，但仍有许多问题需要了解，为什么有些物种具有入侵性，而有些则没有。最近，多倍体（全基因组加倍）被认为是植物入侵性的一个重要决定因素。基因组加倍在植物进化中发挥了重要作用，仅在一代或几代内就可以极大地改变植物的遗传组成、形态、生理和生态。这可能使一些多倍体能够在剧烈波动的环境中成功生存，或者有效地开拓新的栖息地，从而增加其成为入侵物种的潜力。
我们综合了目前关于多倍体对引入植物入侵（即传播）的重要性的知识。我们首先旨在阐明多倍体植物成功所涉及的一般机制，并将其转化为植物入侵物种的成功机制。其次，我们概述了选定的入侵外来植物的倍性水平，并解释了多倍性如何有助于它们的成功。
多倍体可以通过以下几种方式成为物种入侵成功的重要因素：（1）“预先适应”，即多倍体谱系倾向于新分布区的条件，因此在早期定植阶段具有更高的存活率和适应性；（2）由于遗传多样性更大，随后可能会发生适应性，这可能有助于“入侵性的进化”；（3）在杂交后恢复有性繁殖，或者（4）在没有合适配偶的情况下进行无性繁殖。因此，我们鼓励入侵生物学家在研究外来入侵物种时纳入对倍性的评估。
