Symbiosis in a giant protist (Marginopora vertebralis, Soritinae): flexibility in symbiotic partner ships along a natural temperature gradient
Symbiosis in a giant protist (Marginopora vertebralis, Soritinae): flexibility in symbiotic partner ships along a natural temperature gradient
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DOI：
10.3354/meps10465
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发表时间：
2013-01-01
影响因子：
2.5
通讯作者：
Uthicke, Sven
中科院分区：
文献类型：
--
作者：
Momigliano, Paolo;Uthicke, Sven
Soritinae 科的底栖有孔虫是珊瑚礁群落的重要成员，有助于碳酸盐在珊瑚礁上沉积。这些巨型原生生物与共生藻属的微藻形成光共生关系。有孔虫与共生藻伙伴关系的灵活性程度尚不清楚。虽然一些研究表明有孔虫在共生体选择方面表现出很强的特异性，但最近的研究表明，至少有一些类群能够承载 > 1 种共生体类型。我们利用 rDNA 的内部转录间隔区 2 (ITS2)，对分布在西太平洋宽纬度梯度（南纬 31 至 9 度）的 16 个种群中的 369 个个体进行了采样，探索了广泛分布的有孔虫类 (Marginopora vertebralis) 的共生多样性。我们发现 M. vertebralis 与高度多样性的共生藻类型形成共生关联，其中包含来自 4 个主要共生藻分支的 27 种独特的 ITS2 rDNA 单倍型。基于距离的冗余分析表明，观察到的共生群落组成的地理变化与几个海面温度参数相关。共生体多样性在大堡礁近海地区最高，边缘栖息地的特点是环境参数季节性波动较大。在这些地区，我们发现了混合感染的证据，个体宿主具有多种共生谱系。这些发现表明有孔虫与共生藻的伙伴关系具有高度的灵活性，并强调了环境变量在塑造共生关系中的重要性。我们根据以下假设讨论结果：群体内共生体多态性和混合感染可能是应对时间环境波动的机制。
Benthic foraminifera of the family Soritinae are important members of coral reef communities, contributing to carbonate deposition on coral reefs. These giant protists form photosymbiotic associations with microalgae of the genus Symbiodinium. The extent of flexibility in foraminefera-Symbiodinium partnerships is not well understood. While some studies suggest foraminifera exhibit strong specificity with regard to symbiont choice, recent work illustrated that at least a few taxa are able to host >1 symbiont type. We explored the symbiont diversity of a widely distributed soritid foraminifera (Marginopora vertebralis), sampling 369 individuals from 16 populations distributed across a wide latitudinal gradient (31 to 9 degrees S) in the western Pacific Ocean using the internal transcribed spacer region 2 (ITS2) of rDNA. We discovered that M. vertebralis forms symbiotic associations with a high diversity of Symbiodinium types, which encompassed 27 unique ITS2 rDNA haplotypes from 4 major Symbiodinium clades. Distance-based redundancy analysis revealed that the observed geographic variation in symbiont community composition was correlated with several sea surface temperature parameters. Symbiont diversity was highest at the inshore Great Barrier Reef, in marginal habitats characterized by high seasonal fluctuations in environmental parameters. In those areas we found evidence of mixed infections, with individual hosts harboring multiple symbiont lineages. These findings suggest a high degree of flexibility in foraminifera-Symbiodinium partnerships and highlight the importance of environmental variables in shaping symbiotic associations. We discuss the results in light of the hypo thesis that within-population symbiont polymorphism and mixed infections may be a mechanism to cope with temporal environmental fluctuations.