Reciprocal Symbiont Sharing in the Lodging Mutualism between Walking Corals and Sipunculans.
Reciprocal Symbiont Sharing in the Lodging Mutualism between Walking Corals and Sipunculans.
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DOI：
10.1371/journal.pone.0169825
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发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Kato M
中科院分区：
文献类型：
--
作者：
Igawa M;Hata H;Kato M
Heterocyathus属和Heteropsammia属的单生石珊瑚栖息在柔软的海底，不附着在坚硬的底质上。这些属的珊瑚包含一个螺旋状的洞穴，居住着一个在海底漫游的星虫，携带着宿主珊瑚。珊瑚作为一个坚固的庇护所，保护星虫免受可能的捕食者的伤害。与此同时，星虫使珊瑚在柔软的海底保持直立。这种珊瑚星虫协会是独一无二的，因为两个远缘的珊瑚属已经与星虫发展了趋同协会。我们研究了两种珊瑚的趋同进化过程，Hc。aequicostatus和Hp.利用系统发育和形态学分析，对日本冲绳的一种新的脊椎动物--石螺及其共生星虫进行了比较研究。系统发育分析表明，共生星虫包括两个不同的分支，令人惊讶的是，这两个分支都与两个珊瑚物种有关。星虫的身体形态在不同的珊瑚物种之间存在差异，并且适合各自宿主珊瑚的盘绕腔的形态。我们的研究结果表明，这两个珊瑚物种共享两个星虫分支和星虫形态是塑料和由其宿主珊瑚的内部结构。
Solitary scleractinian corals of the genera Heterocyathus and Heteropsammia inhabit soft marine bottoms without attaching to hard substrata. The corallums of these genera contain a coiled cavity inhabited by a sipunculan that roams the seafloor, carrying the host coral with it. The coral serves as a sturdy shelter that protects the sipunculan from possible predators. At the same time, the sipunculan maintains the coral in an upright position on the soft bottom. This coral–sipunculan association is unique because two phylogenetically distant coral genera have developed convergent associations with sipunculans. We investigate the process of convergent evolution of two coral species, Hc. aequicostatus and Hp. cochlea, in Okinawa, Japan, with their symbiotic sipunculans, using phylogenetic and morphological analyses. Phylogenetic analyses clarified that the symbiotic sipunculans comprise two distinct clades, surprisingly both of which are associated with both coral species. The bodily habitus of the sipunculan differed between coral species and fit the morphologies of the coiled cavities of their respective host corals. Our results suggest that the two coral species share two sipunculan clades and that sipunculan morphology is plastic and determined by the internal structure of their host corals.