ARC Centre of Excellence for Coral Reef Studies and College of Science and Engineering, James Cook University, Townsville, QLD, Australia.
AIMS@JCU, Australian Institute of Marine Science and James Cook University, Townsville, QLD, Australia.
Heredity (Edinb). 2018 Dec;121(6):524-536. doi: 10.1038/s41437-018-0059-0. Epub 2018 Feb 17.
Determining the extent to which Symbiodinium communities in corals are inherited versus environmentally acquired is fundamental to understanding coral resilience and to predicting coral responses to stressors like warming oceans that disrupt this critical endosymbiosis. We examined the fidelity with which Symbiodinium communities in the brooding coral Seriatopora hystrix are vertically transmitted and the extent to which communities are genetically regulated, by genotyping the symbiont communities within 60 larvae and their parents (9 maternal and 45 paternal colonies) using high-throughput sequencing of the ITS2 locus. Unexpectedly, Symbiodinium communities associated with brooded larvae were distinct from those within parent colonies, including the presence of types not detected in adults. Bayesian heritability (h) analysis revealed that 33% of variability in larval Symbiodinium communities was genetically controlled. Results highlight flexibility in the establishment of larval symbiont communities and demonstrate that symbiont transmission is not exclusively vertical in brooding corals. Instead, we show that Symbiodinium transmission in S. hystrix involves a mixed-mode strategy, similar to many terrestrial invertebrate symbioses. Also, variation in the abundances of common Symbiodinium types among adult corals suggests that microhabitat differences influence the structure of in hospite Symbiodinium communities. Partial genetic regulation coupled with flexibility in the environmentally acquired component of Symbiodinium communities implies that corals with vertical transmission, like S. hystrix, may be more resilient to environmental change than previously thought.
确定珊瑚中共生藻群落是遗传获得还是环境获得的，对于理解珊瑚的恢复力以及预测珊瑚对海洋变暖等压力的反应至关重要，因为这些压力会破坏这种关键的共生关系。我们通过对 60 个幼虫及其父母（9 个母系和 45 个父系群体）的共生藻群落进行高通量 ITS2 基因座测序，检测了在暂育珊瑚 Seriatopora hystrix 中，共生藻群落垂直传递的保真度以及群落受遗传调控的程度。出乎意料的是，与暂育幼虫相关的共生藻群落与亲代群体中的群落不同，包括在成体中未检测到的类型。贝叶斯遗传力（h）分析表明，幼虫共生藻群落的 33%的变异性受遗传控制。研究结果突出了幼虫共生藻群落建立的灵活性，并表明在暂育珊瑚中，共生体的传递并非完全是垂直的。相反，我们表明 S. hystrix 中的共生体传递涉及一种混合模式策略，类似于许多陆地无脊椎动物共生关系。此外，成年珊瑚中常见共生藻类型的丰度存在差异，这表明微生境差异会影响宿主内共生藻群落的结构。部分遗传调控加上共生藻群落中环境获得成分的灵活性意味着，具有垂直传递的珊瑚，如 S. hystrix，可能比以前认为的更能适应环境变化。
