Data from: Polyploid formation shapes flowering plant diversity

Polyploidy, or whole genome duplication, has been an important feature of eukaryotic evolution. This is especially true in flowering plants, where all extant angiosperms have descended from polyploid species. Here, we present a broad comparative analysis of the effect of polyploidy on flowering plant diversity. We examine the widely held hypothesis that polyploid flowering plants generate more diversity than their diploid counterparts, by fitting stochastic birth/death models to observed ploidal frequency data from 60 extant angiosperm genera. Our results suggest the opposite, that diploids speciate at higher rates than polyploids, through a combination of simple diploid speciation and tetraploidy. Importantly, the estimated diploid advantage stemmed primarily from a higher rate of polyploidization in diploids than polyploids. Our model is also able to account for the empirically observed correlation between polyploidy and species richness without assuming that polyploids have a speciation advantage over diploids.

多倍体化（Polyploidy），即全基因组复制（whole genome duplication），始终是真核生物演化的关键特征之一，这一点在开花植物中尤为显著：所有现存被子植物（angiosperms）均起源于多倍体物种。本研究针对多倍体化对开花植物多样性的影响开展了大规模比较分析。我们针对学界广为接受的“多倍体开花植物的物种多样性生成速率高于二倍体（diploid）对应类群”这一假说，通过将随机出生-死亡模型（stochastic birth/death models）拟合至来自60个现存被子植物属的观测倍性频率数据展开验证。研究结果却与该假说相悖：二倍体的物种形成速率高于多倍体，这一现象由单纯二倍体物种形成与四倍体化（tetraploidy）共同驱动。值得注意的是，估算得到的二倍体优势主要源于二倍体相较于多倍体更高的多倍体化速率。本模型无需假设多倍体相较于二倍体具备物种形成优势，即可解释实证观测到的多倍体化与物种丰富度（species richness）之间的相关性。