Molecular phylogeography, reticulation, and lineage sorting in Mediterranean Senecio sect. Senecio (Asteraceae)
Molecular phylogeography, reticulation, and lineage sorting in Mediterranean Senecio sect. Senecio (Asteraceae)
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DOI：
10.1111/j.0014-3820.2001.tb01312.x
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发表时间：
2001-10-01
期刊：
影响因子：
3.3
通讯作者：
Abbott, RJ
中科院分区：
文献类型：
--
作者：
Comes, HP;Abbott, RJ
塞内西奥的地中海物种群有助于说明可能混淆系统发育推断的进化过程，包括快速多样化、基因树-物种树不一致、网状、位点间协同进化和缺乏完整的谱系分类。通过对18个物种的156个居群（502个个体）进行采样，研究了叶绿体DNA （cpDNA）单倍型变异的系统地理模式，并基于核糖体DNA内部转录间隔区（ITS）序列重建了物种系统发育。对于一个物种子集，随机扩增的多态性dna （rapd）提供了与cpDNA和ITS数据集比较的参考点。鉴定出两类cpDNA单倍型，每种单倍型在地中海地区的某些地区占主导地位。然而，除了S. gallicus外，种内系统地理结构有限，仅检测到少数单倍型具有种特异性。核序列分化度低，几个未解决的系统发育类群暗示了几乎同时的多样化。两个支持良好的ITS分支包含了大多数物种，其中有明显的cpDNA单倍型共享。我们的数据不能诊断网状与谱系分类不足对整个复合体的相对影响。然而，有确凿的证据表明，黄葡萄球菌亚种。短花菊和鲁氏葡萄球菌通过网络从共发生种中获得cpDNA单倍型和ITS序列。相比之下，谱系分类不足是一个可行的假设，cpDNA单倍型共享的S. gallicus和它的近亲。我们利用推测的物种系统发育和相关的分化时间估计了这些单倍型的最小聚合时间。我们的数据表明，根据分子钟校准，祖先的cpDNA多态性可能存活了大约40 - 100万年。
The Mediterranean species complex of Senecio serves to illustrate evolutionary processes that are likely to confound phylogenetic inference, including rapid diversification, gene tree-species tree discordance, reticulation, interlocus concerted evolution, and lack of complete lineage sorting. Phylogeographic patterns of chloroplast DNA (cpDNA) haplotype variation were studied by sampling 156 populations (502 individuals) across 18 species of the complex, and a species phylogeny was reconstructed based on sequences from the internal transcribed spacer (ITS) regions of nuclear ribosomal DNA. For a subset of species, randomly amplified polymorphic DNAs (RAPDs) provided reference points for comparison with the cpDNA and ITS datasets. Two classes of cpDNA haplotypes were identified, with each predominating in certain parts of the Mediterranean region. However, with the exception of S. gallicus, intraspecific phylogeographic structure is limited, and only a few haplotypes detected were species-specific. Nuclear sequence divergence is low, and several unresolved phylogenetic groupings are suggestive of near simultaneous diversification. Two well-supported ITS clades contain the majority of species, amongst which there is a pronounced sharing of cpDNA haplotypes. Our data are not capable of diagnosing the relative impact of reticulation versus insufficient lineage sorting for the entire complex. However, there is firm evidence that S. flavus subsp. breviflorus and S. rupestris have acquired cpDNA haplotypes and ITS sequences from co-occurring species by reticulation. In contrast, insufficient lineage sorting is a viable hypothesis for cpDNA haplotypes shared between S. gallicus and its close relatives. We estimated the minimum coalescent times for these haplotypes by utilizing the inferred species phylogeny and associated divergence times. Our data suggest that ancestral cpDNA polymorphisms may have survived for ca. 0.4-1.0 million years, depending on molecular clock calibrations.