Local adaptation constrains the distribution potential of heat-tolerant Symbiodinium from the Persian/Arabian Gulf.
Local adaptation constrains the distribution potential of heat-tolerant Symbiodinium from the Persian/Arabian Gulf.
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DOI：
10.1038/ismej.2015.80
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发表时间：
2015-12
期刊：
影响因子：
--
通讯作者：
Wiedenmann J
中科院分区：
文献类型：
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作者：
D'Angelo C;Hume BC;Burt J;Smith EG;Achterberg EP;Wiedenmann J
南波斯湾/阿拉伯湾（PAG）的共生珊瑚和单细胞共生藻类（Symbiodinium）显示出特殊的耐热性，能够承受高达36°C的夏季峰值温度。到目前为止，尚不清楚这种恢复力是否与该地区特有的特定共生体类型的存在有关。因此，我们使用分子标记来识别沿太平洋太平洋群岛和阿曼湾bbbb1000公里海岸线的三种Porites物种的共生藻类，并发现最近描述的一种物种，共生嗜热菌，对太平洋太平洋群岛南部珊瑚的生存是不可或缺的，这是世界上最热的海洋。尽管PAG在地理上是孤立的，但我们发现，在邻近的阿曼湾也可以找到嗜热链球菌群的代表，这为耐高温共生体提供了潜在的来源，可能有助于印度洋种群适应未来预期的更高水温。然而，与嗜热链球菌相关的PAG珊瑚不仅对高温有很强的局部适应性，而且对栖息地的高盐度也有很强的适应性。我们表明，当这些珊瑚暴露在其他海洋环境中常见的盐度水平降低时，它们优越的耐热性就会丧失。因此，在PAG以外的大多数珊瑚礁中普遍存在的盐度可能代表了PAG极端耐温珊瑚/共生菌组合的分布障碍。
The symbiotic association of corals and unicellular algae of the genus Symbiodinium in the southern Persian/Arabian Gulf (PAG) display an exceptional heat tolerance, enduring summer peak temperatures of up to 36 °C. As yet, it is not clear whether this resilience is related to the presence of specific symbiont types that are exclusively found in this region. Therefore, we used molecular markers to identify the symbiotic algae of three Porites species along >1000 km of coastline in the PAG and the Gulf of Oman and found that a recently described species, Symbiodinium thermophilum, is integral to coral survival in the southern PAG, the world's hottest sea. Despite the geographic isolation of the PAG, we discovered that representatives of the S. thermophilum group can also be found in the adjacent Gulf of Oman providing a potential source of thermotolerant symbionts that might facilitate the adaptation of Indian Ocean populations to the higher water temperatures expected for the future. However, corals from the PAG associated with S. thermophilum show strong local adaptation not only to high temperatures but also to the exceptionally high salinity of their habitat. We show that their superior heat tolerance can be lost when these corals are exposed to reduced salinity levels common for oceanic environments elsewhere. Consequently, the salinity prevailing in most reefs outside the PAG might represent a distribution barrier for extreme temperature-tolerant coral/Symbiodinium associations from the PAG.