Data from: Exploring Symbiodinium diversity and host specificity in Acropora corals from geographical extremes of Western Australia with 454 amplicon pyrosequencing

Scleractinian corals have demonstrated the ability to shuffle their endosymbiotic dinoflagellate communities (genus Symbiodinium) during periods of acute environmental stress. This has been proposed as a mechanism of acclimation, which would be increased by a diverse and flexible association with Symbiodinium. Conventional molecular techniques used to evaluate Symbiodinium diversity lack the sensitivity to capture accurate estimates of diversity and are unable to identify genetic lineages present at background levels below 10%. Next generation sequencing (NGS) offers a solution to this problem and can resolve microorganism diversity at much finer scales. Here we apply NGS to evaluate Symbiodinium diversity and host specificity in Acropora corals from contrasting regions of Western Australia. The application of 454 pyrosequencing allowed for detection of Symbiodinium operational taxonomic units (OTUs) occurring at frequencies as low as 0.001%, offering a 10 000-fold increase in sensitivity compared to traditional methods. All coral species from both regions were overwhelmingly dominated by a single clade C OTU (accounting for 98% of all recovered sequences). Only 8.5% of colonies associated with multiple clades (clades C and D, or C and G), suggesting a high level of symbiont specificity in Acropora assemblages in Western Australia. This contrasts with recent literature that have applied highly-sensitive molecular techniques and identified widespread flexibility in symbiont associations across a number of coral taxa in other geographic regions. While only 40% of the OTUs were shared between regions, the dominance of a single OTU resulted in no significant difference in Symbiodinium community structure, demonstrating that the coral-algal symbiosis can remain stable across more than 15° of latitude and a range of sea surface temperature profiles. This study validates the use of NGS platforms as tools for providing fine-scale estimates of Symbiodinium diversity and can offer critical insight into the flexibility of the coral-algal symbiosis.石珊瑚（Scleractinian corals）已被证实能够在急性环境胁迫期间重构其体内的内共生甲藻群落（虫黄藻属，Symbiodinium）。这一现象被认为是一种适应性调整机制，而与虫黄藻建立多样化且灵活的共生关系则可强化这一机制。以往用于评估虫黄藻多样性的常规分子技术，其灵敏度不足以准确估算群落多样性，也无法识别占比低于10%本底水平的遗传谱系。下一代测序（NGS）为该问题提供了解决方案，能够以更高的分辨率解析微生物群落多样性。本研究应用下一代测序技术，对西澳大利亚不同区域鹿角珊瑚（Acropora）体内的虫黄藻多样性及宿主专一性进行了评估。454焦磷酸测序技术可检测到频率低至0.001%的虫黄藻操作分类单元（OTUs），其灵敏度较传统方法提升了10000倍。两个区域的所有珊瑚物种均以单一的C分支操作分类单元（OTU）为主导，该OTU占所有回收序列的98%。仅有8.5%的珊瑚群体同时与多个分支的虫黄藻共生（C与D分支，或C与G分支），这表明西澳大利亚海域鹿角珊瑚群落的共生体专一性较高。这一结果与近期文献的发现形成鲜明对比——后者应用高灵敏度分子技术，在其他地理区域的多种珊瑚类群中发现了广泛的共生关系灵活性。尽管两个区域仅有40%的操作分类单元存在共享，但单一优势OTU的存在并未导致虫黄藻群落结构出现显著差异，这证明珊瑚-藻类共生体在超过15°的纬度跨度及多样的海表面温度格局下仍可保持稳定。本研究证实了下一代测序平台可作为精准估算虫黄藻多样性的工具，也能为揭示珊瑚-藻类共生体的灵活性提供关键见解。