What Is the Relationship among Hernandiaceae, Lauraceae, and Monimiaceae, and Why Is This Question So Difficult to Answer?
What Is the Relationship among Hernandiaceae, Lauraceae, and Monimiaceae, and Why Is This Question So Difficult to Answer?
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伞形科、樟科和莫尼米亚科之间的关系是什么？为什么这个问题如此难以回答？
DOI：
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Andre S. Chanderbali
中科院分区：
文献类型：
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作者：
S. Renner;Andre S. Chanderbali
分子和形态上的系统发育研究发现，苍耳科、樟科和落叶松科组成了一个单系群。然而，由于缺乏系统发育信息的替代，这个支系中的科之间的关系仍然不清楚。一般来说，分子系统发育可能会因为各种因素而发生冲突，包括位点和谱系之间的替换率差异、分类单元采样、外群选择和碱基组成偏差。我们分析了Hernandiaceae、Lauraceae和Monimiaceae样本中一个叶绿体内含子、三个间隔区和核26S rRNA基因的一部分共2846个核苷酸序列；我们使用了四个不同替换率的外群。尽管用最大似然法、最小进化法和简约法获得了单一的最佳拓扑结构，但家庭关系仍然像以前的分子研究一样缺乏支持。对数据的探索表明，不同谱系或地点的不同替换率、不充分的分类单元采样、快速进化的外群或有偏见的碱基组成不太可能解释困难的重建。排除一些最长的分枝分类群(半寄生的Cassytha、精选的Hernandiaceae和四个外群中的两个)对拓扑结构没有影响。为了解决这三个科之间的关系，现在可以通过添加这里新采样的樟科、Monimiaceae和Hernandiaceae的基本属来补充现有的五个基因数据集，或者，我们首选的策略是对关键属的低拷贝核基因进行测序，以获得不同类型的数据。
Molecular and morphological phylogenetic studies in the Laurales have found that Hernandiaceae, Lauraceae, and Monimiaceae sensu stricto form a monophyletic group. Because of the paucity of phylogenetically informative substitutions, however, relationships among families within this clade remain unclear. In general, molecular phylogenies may conflict because of a variety of factors, including substitution rate variation among sites and lineages, taxon sampling, outgroup choice, and base compositional biases. We analyzed a total of 2846 aligned nucleotides from a plastid intron, three spacers, and a portion of the nuclear 26S rRNA gene in a sample of Hernandiaceae, Lauraceae, and Monimiaceae; we used four outgroups with differing substitution rates. Despite obtaining single best topologies with maximum likelihood, minimum evolution, and parsimony approaches, family relationships remained as poorly supported as they were in the previous molecular studies. Exploration of the data indicates that varying substitution rates across lineages or sites, insufficient taxon sampling, fast‐evolving outgroups, or biased base composition are unlikely to explain the difficult reconstruction. Exclusion of some of the longest branched taxa (the hemiparasite Cassytha, selected Hernandiaceae, and two of the four outgroups) had no effect on topologies. To resolve relationships among the three families one could now complement existing five‐gene data sets by adding the basal genera of Lauraceae, Monimiaceae, and Hernandiaceae, which are newly sampled here, or, our preferred strategy, by sequencing low‐copy nuclear genes for the key genera to obtain different kinds of data.
影响因子：
6.5
作者：
Rannala, B;Huelsenbeck, JP;Nielsen, R
通讯作者：
Nielsen, R