IntroductionIn the upside-down jellyfish, Cassiopea xamachana (Cnidaria: Scyphozoa), the establishment of photosymbiosis with dinoflagellates (family Symbiodiniaceae) is necessary for the sessile polyp to undergo metamorphosis (strobilation) into a free-swimming adult. C. xamachana has the capacity to associate with a wide variety of dinoflagellate species and representatives of divergent genera. While some studies have looked at the successful induction of symbiosis, none to date have examined the lasting effect of diverse symbiont taxa on host survivorship and development, which is needed to assess the fitness costs of such symbioses.MethodsOur study exposes C. xamachana polyps to 22 different cultured Symbiodinaceae strains representing 13 species from 5 genera. We analyzed the time to strobilation, the number of ephyra (juvenile medusa) produced, and the proportion of ephyra that died prematurely.ResultsHere we show that C. xamachana strobilation can be induced by nearly each symbiodinacean strain we tested, with the exception of free-living species (i.e., unknown to establish symbiosis with any other marine host). Additionally, ephyrae did not display morphological variation or survivorship differences with varying symbionts. However, we observed intraspecific variation in time to induce strobilation with different cultured dinoflagellate strains.DiscussionThis work expands the known symbiont species that can form stable mutualisms with C. xamachana, primarily in the genera Symbiodinium and Breviolum. Additionally, we provide evidence of differences in ability of cultured symbiodiniaceans to establish symbiosis with a host, which suggests population-level differences in dinoflagellate cultures impact their symbiosis success. By utilizing an animal like C. xamachana with flexible symbiont uptake, we are able to explore how symbiont diversity can influence the timing and success of symbiosis-driven development.

中文翻译：

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倒置水母 Cassiopea xamachana 的宿主-共生体可塑性：跨共生体属的斯特罗比

简介在倒置的水母中，仙后座（刺胞动物门：Scyphozoa），与甲藻（共生藻科）建立光共生对于无蒂息肉经历变态（颤动）成为自由游动的成虫是必要的。C. xamachana具有与多种甲藻物种和不同属的代表结合的能力。虽然一些研究着眼于共生的成功诱导，但迄今为止还没有研究过不同共生类群对宿主生存和发育的持久影响，这是评估此类共生的适应成本所必需的。方法我们的研究揭示了C. xamachana水螅体到 22 种不同的培养共生科菌株，代表 5 属 13 种。我们分析了斑纹时间、产生的碟状体（幼年水母）的数量以及过早死亡的碟状体的比例。结果在这里我们表明C. xamachana我们测试的几乎每种共生恐龙菌株都可以诱导颤动，但自由生活的物种除外（即未知与任何其他海洋宿主建立共生）。此外，不同共生体的碟状体并没有表现出形态变异或生存差异。然而，我们观察到了种内时间变化，以诱导不同培养的甲藻菌株的颤动。讨论这项工作扩展了已知的共生体物种，这些共生体物种可以与C. xamachana，主要是在一般情况下共生藻属和短叶草属。此外，我们提供了培养的共生甲藻与宿主建立共生的能力差异的证据，这表明甲藻培养物中种群水平的差异影响其共生的成功。通过利用像这样的动物C. xamachana通过灵活的共生体吸收，我们能够探索共生体多样性如何影响共生驱动发展的时机和成功。