Department of Plant Sciences, University of California, Davis, CA 95616, USA.
Mol Phylogenet Evol. 2011 Dec;61(3):970-7. doi: 10.1016/j.ympev.2011.08.030. Epub 2011 Sep 8.
The Cytisus-Genista complex includes species that have become invasive following introduction into new geographic ranges as ornamental shrubs. Despite their impacts, the evolutionary relationships among invasives, ornamentals, and native-range species have never been investigated. Our objective was to examine relationships within the Cytisus-Genista complex to determine (1) the taxonomic identity of invasive "French broom" and ornamental "sweet broom" and (2) whether "sweet broom" contributes to "French broom" populations directly or via hybridization. We used sequence data from chloroplast and nuclear regions to gain insight into evolutionary origins and to confirm taxonomic status. Our phylogenetic analyses suggest a complex evolutionary history that includes hybridization events. Placement of invasive and ornamental individuals within the Cytisus-Genista complex resolves taxonomic uncertainty in these groups, as our phylogenetic analyses recovered separate "French broom" and "sweet broom" clades within the G. monspessulana clade in the genus Genista. Extensive cloning and sequencing of the ITS region revealed that, although the majority of invasive "French broom" in California is Genista monspessulana, hybridization with individuals from the ornamental "sweet broom" clade likely occurs in populations throughout the state.
金雀花-野豌豆复合群包括一些因作为观赏灌木被引入新的地理范围而成为入侵种的物种。尽管这些入侵种产生了影响，但它们与观赏种和原生种之间的进化关系从未被研究过。我们的目的是研究金雀花-野豌豆复合群内的关系，以确定（1）入侵种“法国金雀花”和观赏种“甜金雀花”的分类身份，以及（2）“甜金雀花”是否直接或通过杂交对“法国金雀花”种群做出贡献。我们使用来自叶绿体和核区的序列数据来深入了解进化起源，并确认分类地位。我们的系统发育分析表明，这一复合群具有复杂的进化历史，包括杂交事件。入侵种和观赏种个体在金雀花-野豌豆复合群中的位置解决了这些群体中的分类不确定性，因为我们的系统发育分析在野豌豆属的 G. monspessulana 分支内恢复了单独的“法国金雀花”和“甜金雀花”分支。对 ITS 区的广泛克隆和测序表明，尽管加利福尼亚州的大多数入侵种“法国金雀花”都是野豌豆属 monspessulana，但在全州的种群中，与观赏种“甜金雀花”分支的个体发生杂交的可能性很大。
