Evidence for horizontal transmission from multilocus phylogeny of deep-sea mussel (Mytilidae) symbionts
Evidence for horizontal transmission from multilocus phylogeny of deep-sea mussel (Mytilidae) symbionts
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DOI：
10.1111/1462-2920.12379
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发表时间：
2014-12-01
影响因子：
5.1
通讯作者：
Cavanaugh, Colleen M.
中科院分区：
文献类型：
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作者：
Fontanez, Kristina M.;Cavanaugh, Colleen M.
深海热液喷口的许多无脊椎动物依靠细菌共生体获得营养，因此共生体垂直（通过卵子或精子）或水平（从环境或当代宿主）传播的机制至关重要。在严格的母体传播模型下，共生体和宿主线粒体基因组通过相同的个体传递，导致一致的宿主-共生体同源性。相比之下，水平传播的共生体是在环境中获得的，导致宿主-共生体系统发育不一致。预计这些传播策略中的每一种都会对共生体生态和基因组进化产生不同的后果。深海贻贝（Bathymodiolinae）分布于全球深海热液喷口，依靠化能自养共生体生存，并被假设为水平传播其共生体。本研究探讨bathymodioline共生生态通过定量的共生体在两个热液喷口和共生体的进化功能基因的遗传。这些共生基因揭示了比16 S核糖体RNA共生基因更为复杂的进化历史，表明水平基因转移可能在共生体基因进化中发挥了重要作用。严格的母系传播假设的测试发现，宿主共生体谱系在多个基因之间显着解耦。这些发现扩展了我们对共生体生态学和进化的理解，并为bathymodioline共生体的水平传播提供了最有力的证据。
Many invertebrates at deep-sea hydrothermal vents depend upon bacterial symbionts for nutrition, and thus the mechanism of symbiont transmission, vertical (via the egg or sperm) or horizontal (from environment or contemporary hosts) is critically important. Under a strict maternal transmission model, symbiont and host mitochondrial genomes pass through the same individuals leading to congruent host-symbiont phylogenies. In contrast, horizontally transmitted symbionts are environmentally acquired, leading to incongruent host-symbiont phylogenies. Each of these transmission strategies is predicted to have different consequences for symbiont ecology and genome evolution. Deep-sea mussels (Bathymodiolinae) are globally distributed at deep-sea hydrothermal vents, depend upon chemoautotrophic symbionts for their survival, and are hypothesized to transmit their symbionts horizontally. This study explored bathymodioline symbiont ecology through quantification of symbionts at two hydrothermal vent sites and symbiont evolution using functional gene phylogenies. These phylogenies revealed a dramatically more complex evolutionary history than 16S ribosomal RNA phylogenies, suggesting that horizontal gene transfer may have played an important role in symbiont gene evolution. Tests of the strict maternal transmission hypothesis found that host-symbiont lineages were significantly decoupled across multiple genes. These findings expand our understanding of symbiont ecology and evolution, and provide the strongest evidence yet for horizontal transmission of bathymodioline symbionts.