Mayfield Anderson B, Chen Chii-Shiarng, Dempsey Alexandra C
National Museum of Marine Biology and Aquarium, Checheng, Pingtung, Taiwan.
Khaled bin Sultan Living Oceans Foundation, Annapolis, Maryland, United States of America.
PLoS One. 2017 Nov 1;12(11):e0185857. doi: 10.1371/journal.pone.0185857. eCollection 2017.
Given the significant threats towards Earth's coral reefs, there is an urgent need to document the current physiological condition of the resident organisms, particularly the reef-building scleractinians themselves. Unfortunately, most of the planet's reefs are understudied, and some have yet to be seen. For instance, the Kingdom of Tonga possesses an extensive reef system, with thousands of hectares of unobserved reefs; little is known about their ecology, nor is there any information on the health of the resident corals. Given such knowledge deficiencies, 59 reefs across three Tongan archipelagos were surveyed herein, and pocilloporid corals were sampled from approximately half of these surveyed sites; 10 molecular-scale response variable were assessed in 88 of the sampled colonies, and 12 colonies were found to be outliers based on employment of a multivariate statistics-based aberrancy detection system. These outliers differed from the statistically normally behaving colonies in having not only higher RNA/DNA ratios but also elevated expression levels of three genes: 1) Symbiodinium zinc-induced facilitator-like 1-like, 2) host coral copper-zinc superoxide dismutase, and 3) host green fluorescent protein-like chromoprotein. Outliers were also characterized by significantly higher variation amongst the molecular response variables assessed, and the response variables that contributed most significantly to colonies being delineated as outliers differed between the two predominant reef coral species sampled, Pocillopora damicornis and P. acuta. These closely related species also displayed dissimilar temporal fluctuation patterns in their molecular physiologies, an observation that may have been driven by differences in their feeding strategies. Future works should attempt to determine whether corals displaying statistically aberrant molecular physiology, such as the 12 Tongan outliers identified herein, are indeed characterized by a diminished capacity for acclimating to the rapid changes in their abiotic milieu occurring as a result of global climate change.
鉴于地球珊瑚礁面临的重大威胁，迫切需要记录当地生物的当前生理状况，尤其是造礁石珊瑚本身。不幸的是，地球上大部分珊瑚礁研究不足，有些甚至尚未被发现。例如，汤加王国拥有广泛的珊瑚礁系统，有成千公顷未被观测的珊瑚礁；人们对它们的生态了解甚少，也没有关于当地珊瑚健康状况的任何信息。鉴于这些知识空白，本文对汤加三个群岛的59个珊瑚礁进行了调查，并从大约一半的调查地点采集了鹿角珊瑚样本；在88个采样群体中评估了10个分子水平的响应变量，基于多变量统计异常检测系统，发现有12个群体为异常值。这些异常值与统计上正常的群体不同，不仅具有更高的RNA/DNA比率，而且三个基因的表达水平也有所升高：1）共生藻锌诱导促进因子样1样蛋白，2）宿主珊瑚铜锌超氧化物歧化酶，3）宿主绿色荧光蛋白样色素蛋白。异常值的另一个特征是，在所评估的分子响应变量中，变异程度显著更高，并且在两种主要的礁珊瑚物种——鹿角珊瑚和尖锐鹿角珊瑚中，对群体被划定为异常值贡献最大的响应变量也有所不同。这些密切相关的物种在分子生理方面也表现出不同的时间波动模式，这一观察结果可能是由它们的摄食策略差异所驱动的。未来的研究应尝试确定，表现出统计异常分子生理的珊瑚，如本文中确定的12个汤加异常值，是否确实具有适应因全球气候变化而导致的非生物环境快速变化的能力下降的特征。
