Paraphyly of Tarasa (Malvaceae) and Diverse Origins of the Polyploid Species
Paraphyly of Tarasa (Malvaceae) and Diverse Origins of the Polyploid Species
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DOI：
10.1043/02-64.1
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发表时间：
2003-10
期刊：
影响因子：
--
通讯作者：
J. Tate;B. Simpson
中科院分区：
文献类型：
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作者：
J. Tate;B. Simpson
摘要/ Abstract摘要：对安第斯山凤梨属（malvacae）及其近属进行了分子系统发育分析，在属界、多倍体起源和多倍体分类群形态特征等方面得到了意想不到的结果。塔拉萨的多倍体物种特别不寻常，因为它们的生活史和花形态与两种传统的多倍体学说相矛盾：它们是一年生的，比二倍体物种有更小的花特征（包括花粉）。多倍体通常是多年生的，比亲本大。利用核（ITS1, 5.8S和ITS2）和叶绿体（psbA-trnH和trnT-trnL间隔子，matK-3 ' trnK内含子）序列数据重建独立的系统发育，以检验该属的单系性，确定其姐妹类群，并研究多倍体物种的起源。核系统发育和叶绿体系统发育都不支持目前所限定的塔拉沙单系。高安第斯山脉的Nototriche属，南北美洲分离的Sphaeralcea属和Malacothamnus chilensis被归为Tarasa分支。多倍体物种不是单系的，因此是多次产生的。这些发现表明，四倍体不同寻常的形态特征是趋同进化的结果，而不是共同祖先的结果。
Abstract A molecular phylogenetic analysis of the Andean genus Tarasa (Malvaceae) and related genera yielded unexpected results regarding generic boundaries, the origins of polyploidy, and the morphological attributes of the polyploid taxa. The polyploid species of Tarasa are particularly unusual because they have life histories and floral morphologies that contradict two traditional polyploid dogmas: they are annuals and have smaller floral features (including pollen) than the diploid species. Typically, polyploids are perennial and larger than their parents. Nuclear (ITS1, 5.8S, and ITS2) and chloroplast (psbA-trnH and trnT-trnL spacers, matK-3′ trnK intron) sequence data were used to reconstruct independent phylogenies to test the monophyly of the genus, determine its sister group(s), and investigate the origin of the polyploid species. Neither the nuclear nor the chloroplast phylogeny supports monophyly of Tarasa as currently circumscribed. The high Andean genus Nototriche, the North/South American disjunct genus Sphaeralcea, and Malacothamnus chilensis are placed within the Tarasa clade. The polyploid species of Tarasa are not monophyletic and thus have been generated multiple times. These findings suggest that the unusual morphological features of the tetraploids are the result of convergent evolution and not shared ancestry.