人们一直怀疑多倍性即基因组拷贝数的增加在新植物种起源中是否扮演着重要角色。现存的被子植物有40%到80%被认为是多倍体。当前估计显示仅有3%到4%的植物是由更晚的多倍体相关的物种分化而来的。

　　最近，德国明斯特大学、美国阿拉斯加大学和加拿大英属哥伦比亚大学的研究人员提供证据证明多倍性是植物物种形成的主要原因。研究人员证实15%的开花植物以及30%的蕨类植物均是由多倍性直接产生的。这些研究人员由Troy Wood领导，他们采用细胞遗传学方法及系统进化方法研究了一系列维管植物中出现多倍性的频率，对新物种的出现尤其关注。

　　然而研究人员却发现，以多倍体植物为祖先的植物类群并不比以二倍体植物为祖先的类群更容易产生物种。文章作者之一Loren Rieseberg说：“多倍性似乎对多样化速率没有作用，这一事实会减少人们有关“多倍性优势”的说法。”

　　生物谷推荐原始出处：

　　PNAS August 18, 2009 vol. 106 no. 33 13875-13879

The frequency of polyploid speciation in vascular plants

Troy E. Wooda,b,1, Naoki Takebayashic, Michael S. Barkerb,d, Itay Mayrosee, Philip B. Greenspoond and Loren H. Riesebergb,d

　　aInstitute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany;

　　bDepartment of Biology, Indiana University, Bloomington, IN 47405;

　　cInstitute of Arctic Biology and Department of Biology and Wildlife, University of Alaska, Fairbanks, AK 99775; and

　　Departments of dBotany and

　　eZoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4

　　Since its discovery in 1907, polyploidy has been recognized as an important phenomenon in vascular plants, and several lines of evidence indicate that most, if not all, plant species ultimately have a polyploid ancestry. However, previous estimates of the frequency of polyploid speciation suggest that the formation and establishment of neopolyploid species is rare. By combining information from the botanical community's vast cytogenetic and phylogenetic databases, we establish that 15% of angiosperm and 31% of fern speciation events are accompanied by ploidy increase. These frequency estimates are higher by a factor of four than earlier estimates and lead to a standing incidence of polyploid species within genera of 35% (n = 1,506). Despite this high incidence, we find no direct evidence that polyploid lines, once established, enjoy greater net species diversification. Thus, the widespread occurrence of polyploid taxa appears to result from the substantial contribution of polyploidy to cladogenesis, but not from subsequent increases in diversification rates of polyploid lines.