PHYLOGENY OF LEAVENWORTHIA S-ALLELES SUGGESTS UNIDIRECTIONAL MATING SYSTEM EVOLUTION AND ENHANCED POSITIVE SELECTION FOLLOWING AN ANCIENT POPULATION BOTTLENECK
PHYLOGENY OF LEAVENWORTHIA S-ALLELES SUGGESTS UNIDIRECTIONAL MATING SYSTEM EVOLUTION AND ENHANCED POSITIVE SELECTION FOLLOWING AN ANCIENT POPULATION BOTTLENECK
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DOI：
10.1111/j.1558-5646.2011.01564.x
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发表时间：
2012-06-01
期刊：
影响因子：
3.3
通讯作者：
Schoen, Daniel J.
中科院分区：
文献类型：
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作者：
Herman, Adam C.;Busch, Jeremiah W.;Schoen, Daniel J.
从祖先异交状态到自花受精是显花植物中最常见的进化转变之一。在芥菜科中，异交通常是由孢子体自交不亲和性（SI）来执行的，但也有许多自交亲和的物种。Leavenacrotia属包含具有或缺乏SI的分类群。在这里，我们目前的数据表明，SI与严格的异交，并有广泛的反式特异性序列多态性的基因座参与识别自花粉（S-位点）。这种祖先的多态性是一致的存在下，一个异交交配系统的Leavenacrotia物种的共同祖先，并建议有几个独立的损失SI组。当与其他芥菜物种相比，大量的Leavenoclavenia S-等位基因序列是高度偏离那些发现在其他芥菜科，并显示出相对较低的水平的核苷酸多样性，这种模式表明该属的共同祖先可能经历了一个强大的人口瓶颈。瓶颈后的S-位点再多样化的假设是支持的测试表明更强的正选择作用于S-等位基因的Leavenacroia比那些发现在其他的菊科。
The adoption of self-fertilization from an ancestral outcrossing state is one of the most common evolutionary transitions in the flowering plants. In the mustard family, outcrossing is typically enforced by sporophytic self-incompatibility (SI), but there are also many self-compatible species. The genus Leavenworthia contains taxa that either possess or lack SI. Here, we present data showing that SI is associated with strict outcrossing and that there is widespread trans-specific sequence polymorphism at the locus involved in the recognition of self-pollen (the S-locus). This ancestral polymorphism is consistent with the presence of an outcrossing mating system in the common ancestor of Leavenworthia species, and suggests that there have been several independent losses of SI in the group. When compared with other mustard species, the bulk of Leavenworthia S-allele sequences are highly diverged from those found in other Brassicaceae and show relatively low levels of nucleotide diversity, a pattern that suggests the common ancestor of the genus likely underwent a strong population bottleneck. The hypothesis of postbottleneck S-locus rediversification is supported by tests showing stronger positive selection acting on S-alleles from Leavenworthia than those found in other Brassicaceae.