Nonuniform concerted evolution and chloroplast capture:: Heterogeneity of observed introgression patterns in three molecular data partition phylogenies of Asian Mitella (Saxifragaceae)
Nonuniform concerted evolution and chloroplast capture:: Heterogeneity of observed introgression patterns in three molecular data partition phylogenies of Asian Mitella (Saxifragaceae)
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DOI：
10.1093/molbev/msi016
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发表时间：
2005-02-01
影响因子：
10.7
通讯作者：
Kato, M
中科院分区：
文献类型：
--
作者：
Okuyama, Y;Fujii, N;Kato, M
种间杂交是导致基因座间属间不一致的主要因素之一。但是关于每个基因座在物种间渗入的潜力的知识仍然有限。通过直接测序叶绿体DNA（matK基因和trnL-F非编码区）、核核糖体外转录间隔区（ETS）和内转录间隔区（ITS）三个DNA区域。摘要我们构建了三个亚洲物种的系统发育树，Mitella（虎耳草科）是一个多年生植物属，其中自然杂交是常见的。在这个属里。在叶绿体和核同源性之间以及在ETS和ITS之间存在显著的拓扑冲突，这可以归因于谱系内的频繁杂交。叶绿体DNA表现出最广泛的渐渗模式，ITS区表现出中等渐渗模式。ETS区域没有显示出基因渗入的证据。不一致的协同进化最好地解释了ETS区域和ITS区域之间的渐渗模式的差异，因为个体基因组内ITS区域的序列异质性估计是该谱系中ETS的两倍。在克隆的ETS-ITS序列的连续阵列中观察到两个杂交类群之间的显著基因转换模式，进一步证实只有ITS区域双向渗入。ITS区相对缓慢的协同进化可能允许基因组内多个等位基因的共存，而ETS区强烈的协同进化迅速消除了来自其他物种的异质等位基因，导致物种划分与基于形态学的高度一致。这一发现表明，使用多种分子工具有可能揭示详细的生物进化过程，涉及种间杂交，作为一个单独的基因座差异很大，在其潜在的物种之间的渗入。
Interspecific hybridization is one of the major factors leading to phylogeneric incongruence among loci. but the knowledge is still limited about the potential of each locus to introgress between species. By directly sequencing three DNA regions: chloroplast DNAs (matK gene and trnL-F noncoding region), the nuclear ribosomal external transcribed spacer (ETS) region, and internal transcribed spacer (ITS) regions. we construct three phylogenetic trees of Asian species of Mitella (Saxifragaceae), a genus of perennials in which natural hybrids are commonly observed. Within this genus. there is a significant topological conflict between chloroplast and nuclear phylogenies and also between the ETS and the ITS, which can be attributed to frequent hybridization within the lineage. Chloroplast DNAs show the most extensive introgression pattern, ITS regions show a moderate pattern. and the ETS region shows no evidence of introgression. Nonuniform concerted evolution best explains the difference in the introgression patterns between the ETS region and ITS regions, as the sequence heterogeneity of the ITS region within an individual genome is estimated to be twice that of an ETS in this lineage. Significant gene conversion patterns between two hybridizing taxa were observed in contiguous arrays of cloned ETS-ITS sequences, further confirming that only ITS regions have introgressed bidirectionally. The relatively slow concerted evolution in the ITS regions probably allows the coexistence of multiple alleles within a genome, whereas the strong concerted evolution in the ETS region rapidly eliminates heterogeneous alleles derived from other species, resulting in species delimitations highly concordant with those based on morphology. This finding indicates that the use of multiple molecular tools has the potential to reveal detailed organismal evolution process involving interspecific hybridization, as an individual locus varies greatly in its potential to introgress between species.