A phylogenetic hypothesis for the recently diversified Ruschieae (Aizoaceae) in southern Africa.
A phylogenetic hypothesis for the recently diversified Ruschieae (Aizoaceae) in southern Africa.
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DOI：
10.1016/j.ympev.2013.05.030
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发表时间：
2013-12
影响因子：
4.1
通讯作者：
C. Klak;P. Bruyns;P. Hanáček
中科院分区：
文献类型：
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作者：
C. Klak;P. Bruyns;P. Hanáček
该Ruschieae是一个大的族约1600种的肉质多年生植物。它们构成了大好望角植物区的干旱地区的主要组成部分，无论是在物种数量和覆盖密度方面。到目前为止，部落内的系统发育关系尚未解决，主要是通过缺乏可变的分子特征，这是由于部落的最近和快速辐射。我们的基因组学是基于10个叶绿体基因区域，代表了目前公认的100个属的Ruschieae几乎完整的采样。这些叶绿体区域产生了相对较少的染色体遗传信息性状，因此仅提供有限的分辨率和对染色体发生的许多部分的支持不足。然而，第一次，我们提供了有力的证据，大多是介形的，往往是短暂的叶和弱宿存的果实类群形成的Ruschieae的血统的基础等级。这些谱系对着一个大的多歧分类群，几乎完全旱生，宿存叶和强烈持续的果实。在基础等级的谱系中，那些发生在冬季降雨地区的谱系通常在干燥的夏季月份脱落叶子或在顶芽周围形成（至少部分）保护性的干燥鞘，作为逃避夏季干旱的手段。这与冬季降雨区以外的基础等级的类群形成对比，其中叶子持续存在。我们的研究结果表明，在强和弱宿存的水果，专门的特点反复演变的水果，所以这些结构是高度homoplasious。也许是由于不断增加的持久性和专门化的叶和果实的变化，几个分支表现出很少的形态凝聚力。然而，在其他组在开普植物群，大多数分支在Ruschieae代表区域集团。我们的核基因“叶绿体表达的谷氨酰胺合成酶”（ncpGS）的序列分析揭示了广泛的paralogy内Ruschieae，但发现一个完整的阅读框架，在其所有成员。需要更多的数据的Ruschieae的细胞学，以评估是否paralogy观察到的是由于基因重复或多倍体。
The Ruschieae is a large tribe of about 1600 species of succulent perennials. They form a major component of the arid parts of the Greater Cape Floristic Region, both in numbers of species and in their density of coverage. So far phylogenetic relationships within the tribe have been unresolved, largely through the paucity of variable molecular characters and this is ascribed to the tribe’s recent and rapid radiation. Our phylogeny is based on 10 chloroplast gene regions and represents a nearly complete sampling of the 100 currently recognised genera of the Ruschieae. These chloroplast regions yielded relatively few phylogenetically informative characters, consequently providing only limited resolution in and poor support for many parts of the phylogeny. Nevertheless, for the first time, we provide well-supported evidence that taxa with mostly mesomorphic, often ephemeral leaves and weakly persistent fruits form a basal grade of lineages in the Ruschieae. These lineages subtend a large polytomy of taxa with almost exclusively xeromorphic, persistent leaves and strongly persisting fruits. Among the basal grade of lineages, those occurring within the winter-rainfall region typically shed their leaves or form (at least partly) a protective, dry sheath around the apical bud during the dry summer months, as a means of escaping the summer drought. This contrasts with taxa of the basal grade from outside the winter-rainfall region, in which the leaves persist. Our results show that, in both strongly and weakly persistent fruits, specialised characteristics of the fruit evolved repeatedly and so these structures are highly homoplasious. Perhaps as a consequence of repeated changes towards increased persistence and specialisation of leaves and fruits, several clades show little morphological cohesion. However, as in other groups in the Cape Flora, most clades in the Ruschieae represent regional groupings. Our analysis of sequences of the nuclear gene ‘chloroplast-expressed glutamine synthetase’ (ncpGS) revealed extensive paralogy within the Ruschieae, but found an intact reading frame in all its members. More data on the cytology of the Ruschieae is needed to evaluate whether the paralogy observed is due to gene duplication or polyploidy.