ARE SPURRED CYATHIA A KEY INNOVATION? MOLECULAR SYSTEMATICS AND TRAIT EVOLUTION IN THE SLIPPER SPURGES (PEDILANTHUS CLADE: EUPHORBIA, EUPHORBIACEAE)
ARE SPURRED CYATHIA A KEY INNOVATION? MOLECULAR SYSTEMATICS AND TRAIT EVOLUTION IN THE SLIPPER SPURGES (PEDILANTHUS CLADE: EUPHORBIA, EUPHORBIACEAE)
复制标题
DOI：
10.3732/ajb.0900090
复制
发表时间：
2010-03-01
影响因子：
3
通讯作者：
Baum, David A.
中科院分区：
文献类型：
--
作者：
Cacho, N. Ivalu;Berry, Paul E.;Baum, David A.
研究在促进多样化方面发挥关键作用的性状是进化生物学的核心。花蜜刺是少数几个与提高多样化率相关的植物性状之一，支持它们是关键创新的说法。轻微的变化，马刺形态可能会赋予一定程度的交配前隔离，解释为什么分支与马刺往往包括更多的物种比他们的spurless近亲。我们探讨了杯状花蜜刺的Pedilanthus分支（大戟属）是否也可以作为一个关键的创新。我们估计使用一个质体（matK）和三个核区域（ITS和两个G3PDH基因座）的Pedilanthus分支，并使用我们的研究结果和一个Yule模型的多样化来测试的假设，即杯突刺与增加多样化率。我们发现，缺乏统计支持的关键创新假设，除非特定的假设，关于创业适用。然而，这一群体的年轻（因此规模较小）可能限制我们发现多样化率显著增加的能力。此外，我们的研究结果证实了以前的物种名称，表明更高的同质性杯状比营养功能，并建议一个可能的中美洲起源的组。
The study of traits that play a key role in promoting diversification is central to evolutionary biology. Floral nectar spurs are among the few plant traits that correlate with an enhanced rate of diversification, supporting the claim that they are key innovations. Slight changes in spur morphology could confer some degree of premating isolation, explaining why clades with spurs tend to include more species than their spurless close relatives. We explored whether the cyathial nectar spur of the Pedilanthus clade (Euphorbia) may also function as a key innovation. We estimated the phylogeny of the Pedilanthus clade using one plastid (matK) and three nuclear regions (ITS and two G3pdh loci) and used our results and a Yule model of diversification to test the hypothesis that the cyathial spur correlates with an increased diversification rate. We found a lack of statistical support for the key innovation hypothesis unless specific assumptions regarding the phylogeny apply. However, the young age (hence small size) of the group may limit our ability to detect a significant increase in diversification rate. Additionally, our results confirm previous species designations, indicate higher homoplasy in cyathial than in vegetative features, and suggest a possible Central American origin of the group.