Molecular phylogenetic dating of asterid flowering plants shows early Cretaceous diversification
Molecular phylogenetic dating of asterid flowering plants shows early Cretaceous diversification
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DOI：
10.1080/10635150490445913
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发表时间：
2004-06-01
影响因子：
6.5
通讯作者：
Bremer, B
中科院分区：
文献类型：
--
作者：
Bremer, K;Friis, EM;Bremer, B
我们提出了一个系统发育的测年，基于一个111分类群树代表所有主要群体和订单和83的102个家庭的植物，一个基本的数据集，包括6个叶绿体DNA标记，共9914个位置。系统发生年代测定是通过惩罚似然法进行半参数速率平滑的。通过bootstrapping计算置信区间。六个参考化石用于校准。为了探索各种来源的误差的影响，我们重复了分析与替代的定年方法（非参数速率平滑和Langley-Fitch时钟为基础的方法），替代树拓扑结构，减少分类单元采样（删除22的111个分类单元），数据划分为三个基因和三个非编码区，并校准与单一的参考化石。替代拓扑结构的分析，减少分类单元采样，编码与非编码序列都产生了小的或在某些情况下没有偏差。方法的选择影响了一些节点的年龄估计相当大。使用参考化石进行校准是一个关键问题，使用单一参考化石会产生不同的结果。Bootstrap置信区间通常较小。我们的研究结果表明，在早白垩世，珊瑚和它们的主要亚群euglids，campanulids和lamiids多样化。Cornales，Ericales和Aquifoliales也有早白垩世的冠节年龄。Dipsacales和Solanales来自中白垩世，其他核心钟形目和核心纹层目来自晚白垩世。几乎从化石记录中第一次出现起，恐龙就表现出了相当大的多样性，这也支持了早白垩世物种多样性的起源和第一阶段。
We present a phylogenetic dating of asterids, based on a 111-taxon tree representing all major groups and orders and 83 of the 102 families of asterids, with an underlying data set comprising six chloroplast DNA markers totaling 9914 positions. Phylogenetic dating was done with semiparametric rate smoothing by penalized likelihood. Confidence intervals were calculated by bootstrapping. Six reference fossils were used for calibration. To explore the effects of various sources of error, we repeated the analyses with alternative dating methods (nonparametric rate smoothing and the Langley-Fitch clock-based method), alternative tree topologies, reduced taxon sampling (22 of the 111 taxa deleted), partitioning the data into three genes and three noncoding regions, and calibrating with single reference fossils. The analyses with alternative topologies, reduced taxon sampling, and coding versus noncoding sequences all yielded small or in some cases no deviations. The choice of method influenced the age estimates of a few nodes considerably. Calibration with reference fossils is a critical issue, and use of single reference fossils yielded different results depending on the fossil. The bootstrap confidence intervals were generally small. Our results show that asterids and their major subgroups euasterids, campanulids, and lamiids diversified during the Early Cretaceous. Cornales, Ericales, and Aquifoliales also have crown node ages from the Early Cretaceous. Dipsacales and Solanales are from the Mid-Cretaceous, the other orders of core campanulids and core lamiids from the Late Cretaceous. The considerable diversity exhibited by asterids almost from their first appearance in the fossil record also supports an origin and first phase of diversification in the Early Cretaceous.