Wood Troy E, Takebayashi Naoki, Barker Michael S, Mayrose Itay, Greenspoon Philip B, Rieseberg Loren H
Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany.
Proc Natl Acad Sci U S A. 2009 Aug 18;106(33):13875-9. doi: 10.1073/pnas.0811575106. Epub 2009 Aug 10.
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.
自1907年被发现以来，多倍体一直被认为是维管植物中的一种重要现象，而且有几条证据表明，即使不是所有植物物种，大多数最终都有多倍体祖先。然而，先前对多倍体物种形成频率的估计表明，新多倍体物种的形成和建立是罕见的。通过整合植物学界庞大的细胞遗传学和系统发育数据库中的信息，我们确定15%的被子植物和31%的蕨类植物物种形成事件伴随着倍性增加。这些频率估计比早期估计高出四倍，导致属内多倍体物种的现存发生率为35%（n = 1506）。尽管发生率很高，但我们没有发现直接证据表明多倍体系一旦建立就能享有更大的净物种多样化。因此，多倍体类群的广泛存在似乎是由于多倍体对分支形成的重大贡献，而不是由于多倍体系随后多样化速率的增加。
