Molecular phylogeny and evolution of symbiosis in a clade of Indopacific nudibranchs.
Molecular phylogeny and evolution of symbiosis in a clade of Indopacific nudibranchs.
复制标题
印度太平洋裸鳃类分支的分子系统发育和共生进化。
DOI：
10.1016/j.ympev.2010.11.008
复制
发表时间：
2011
影响因子：
4.1
通讯作者：
T. Gosliner
中科院分区：
文献类型：
--
作者：
E. Moore;T. Gosliner
以前基于形态学分析理解叶束属进化的努力一直受到缺乏支持的进化论的困扰（Ortiz和Gosliner，2008;摩尔和Gosliner，2009，出版中）。有人提出（摩尔和Gosliner，2009），分子遗传学可能提供更多的洞察力，这一历史比可以很容易地发现使用形态学数据。本研究测定了18种叶束藻和6种外类群的细胞色素C氧化酶亚基I（CO 1）基因658 bp、线粒体核糖体大亚基（16 S）基因441 bp和编码蛋白质的核基因（组蛋白3）328 bp的序列。共有464个简约信息网站被用于简约，最大似然，贝叶斯推理的遗传分析。所有三种分析都产生了类似的拓扑结构，除了简约分析中的一个差异。Bootstrap值和后验概率在许多浅节点提供了强有力的支持，在每种情况下，Phyllodesmium的单系性都得到了支持。在这一分析中，Phyllodesmium的三个不同的分支是明显的。其中之一代表了大多数非共生类群。非共生种波氏叶丝藻显然是共生分支的成员，并且似乎已经二次失去了与虫黄藻的共生关系。有适度的支持，证实了类似的拓扑趋势，在早期的形态共生，包括假说，共生物种与zooxanthropy的进化最近比非共生物种。尽管包含了一个可能保守的核位点，一些深节点仍然没有得到解决或没有得到很好的支持。未来包括额外的类群和更缓慢地演变的基因座可能会提高这些更深的节点的分辨率。随后的消化系统发生支持了Rudman（1991）、Kempf（1991）和Burghardt等人（2008 b）先前的假设，即更复杂的消化腺结构的进化与与虫黄藻共生复杂性的增加和光合活性的更高效率有关。我们的共生关系也表明，这种共生只进化了一次Phyllodesmium和azooxanthellate物种的姐妹，而不是基础，zooxanthellate物种。
Previous efforts at understanding the evolution of the genus Phyllodesmium, based on morphological analyses, have been plagued by poorly supported phylogenies (Ortiz and Gosliner, 2008; Moore and Gosliner, 2009, in press). It has been suggested (Moore and Gosliner, 2009) that a molecular phylogeny might provide more insight into this history than can be easily discovered using morphological data. In this study, 658bp of the cytochrome c oxidase subunit I gene (CO1), 441bp of the mitochondrial large ribosomal subunit (16S) gene, and 328bp of a protein-coding nuclear gene (histone 3) were sequenced for 18 species of Phyllodesmium and six outgroup species. A total of 464 parsimony informative sites were used for parsimony, maximum likelihood, and Bayesian inference of phylogeny analyses. All three analyses produced similar topologies, with the exception of a single difference within the parsimony analysis. Bootstrap values and posterior probabilities provided strong support at many shallow nodes, and the monophyly of Phyllodesmium was supported in every case. Three distinct clades of Phyllodesmium are evident in this analysis. One of these represents the majority of asymbiotic taxa. Phyllodesmium poindimiei, an asymbiotic species, is clearly a member of a symbiotic clade and appears to have secondarily lost its symbiotic relationship with zooxanthellae. There was moderate support confirming similar topological trends seen in earlier morphological phylogenies, including the hypothesis that symbiotic species associating with zooxanthellae have evolved more recently than non-symbiotic species. Despite the inclusion of a presumably conservative nuclear locus, some deep nodes are still unresolved or are not well supported. Future inclusion of additional taxa and more slowly evolving loci will likely improve resolution of these deeper nodes. The subsequent phylogeny supports previous hypotheses by Rudman (1991), Kempf (1991) and Burghardt et al. (2008b) that evolution of more complex digestive gland structures is related to increased complexity of symbiosis with zooxanthellae and greater efficiency of photosynthetic activity. Our phylogeny also demonstrates that this symbiosis has evolved only once in Phyllodesmium and that azooxanthellate species are sister, rather than basal, to zooxanthellate species.