Insights into the systematics, phylogeny, and evolution of Cladobranchia (Gastropoda: Heterobranchia)
Insights into the systematics, phylogeny, and evolution of Cladobranchia (Gastropoda: Heterobranchia)
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DOI：
10.4003/006.035.0111
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发表时间：
2017-05-01
影响因子：
0.5
通讯作者：
Goodheart, Jessica A.
中科院分区：
文献类型：
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作者：
Goodheart, Jessica A.
枝鳃类是裸鳃类腹足动物的一个多样化分支，有类似于1,000个沿海（底栖）和远离海岸（远洋）的海洋物种。它们的多样性可能与饮食专业化和动物中罕见的显著适应性的进化有关，例如刺胞动物包囊的隔离。由于在枝鳃类和软体动物门内的其他高阶类群之间存在着深刻的分歧，基于形态学或一些基因的系统发育分析无法以高支持率解决这些分支内的关系。然而，高通量测序技术的引入提供了收集大型基因组数据集的机会，这些数据集已被证明在解决软体动物内的关系方面是有用的，就像在其他后生动物组中一样。随着测序成本的降低，收集更大的数据集以试图解决最近分歧的群体（如枝鳃类）之间的关系变得越来越容易。枝鳃类内三个主要类群（Arminida、Dendronotida和Aeolidida）的系统发育和亲缘关系一直难以确定，主要是由于传统分子系统发育研究中分析的mtDNA和rDNA基因的快速进化。在这篇综述中，我讨论了枝鳃类的系统学方面的形态数据，分子分析与一个或几个基因，并解决基因组数据的影响。然后，我认为高通量测序数据提供的支持系统发育假说将为研究枝鳃类内的分类和特征进化提供一个更好的框架，因为这些数据为枝鳃类本身以及其中的嵌套亚支提供了强有力的支持。很明显，利用这些数据提供了迄今为止支持最充分的枝鳃类系统发育假说。在这样做的过程中，这些基因组数据挑战了已经建立的关系，包括Facelinidae的单系性和在Dendronotida中包含Tritoniidae，并解决了传统上很难放置的分类群的位置，包括Melibe Rang，1829和Proctonotidae和Dironidae。最后，这些基因组数据提供了一个更强大的系统发育框架内枝鳃类的研究字符的进化，包括在这个分支的典型特征之一的包囊隔离的演变。
Cladobranchia is a diverse clade of nudibranch gastropods, with similar to 1,000 coastal (benthic) and off shore (pelagic) marine species. Their diversity may be tied to dietary specialization and the evolution of remarkable adaptations that are rare among animals, such as the sequestration of cnidarian nematocysts. Due to the deep divergences within Cladobranchia, and other higher-order taxa within Mollusca, phylogenetic analyses based on morphology or a few genes have been unable to resolve relationships within these clades with high support. The introduction of high-throughput sequencing technologies, however, has provided the opportunity to collect large genomic data sets, which have proven useful in resolving relationships within molluscs, as in other metazoan groups. As sequencing costs decrease, it has become easier to collect ever larger data sets in an attempt to resolve relationships within more recently diverged groups, such as Cladobranchia. The phyly and relationships of the three main groups within Cladobranchia (Arminida, Dendronotida, and Aeolidida) have been diffi cult to determine, primarily due to the rapid evolution of mtDNA and rDNA genes analyzed in traditional molecular phylogenetic studies. In this review, I discuss the systematics of Cladobranchia in regards to morphological data, molecular analyses with one or a few genes, and address the impact of genomic data. I then contend that the supported phylogenetic hypotheses provided by high-throughput sequencing data will provide a better framework for studying taxonomy and character evolution within Cladobranchia, as these data provide strong support for Cladobranchia itself, as well as the nested subclades within it. Although it is important to note that a broader taxon sampling is still needed for genomic data, it is clear that utilizing these data has provided the most-well-supported phylogenetic hypotheses of Cladobranchia to date. In doing so, these genomic data have challenged well-established relationships, including the monophyly of Facelinidae and inclusion of Tritoniidae in Dendronotida, and resolved the position of taxa that have been traditionally quite diffi cult to place, including Melibe Rang, 1829 and the families Proctonotidae and Dironidae. Finally, these genomic data provide a much stronger phylogenetic framework for studying character evolution within Cladobranchia, including the evolution of nematocyst sequestration, one of the quintessential characters in this clade.