Department of Biology, University of Victoria, PO Box 1700 Station CSC, Victoria, British Columbia V8W 2Y2, Canada.
UWA Oceans Institute and School of Biological Sciences, University of Western Australia, Crawley, WA 6009, Australia.
Sci Adv. 2023 Aug 11;9(32):eadf0954. doi: 10.1126/sciadv.adf0954.
Climate change-amplified marine heatwaves can drive extensive mortality in foundation species. However, a paucity of longitudinal genomic datasets has impeded understanding of how these rapid selection events alter cryptic genetic structure. Heatwave impacts may be exacerbated in species that engage in obligate symbioses, where the genetics of multiple coevolving taxa may be affected. Here, we tracked the symbiotic associations of reef-building corals for 6 years through a prolonged heatwave, including known survivorship for 79 of 315 colonies. Coral genetics strongly predicted survival of the ubiquitous coral, (massive growth form), with variable survival (15 to 61%) across three morphologically indistinguishable-but genetically distinct-lineages. The heatwave also disrupted strong associations between these coral lineages and their algal symbionts (family Symbiodiniaceae), with symbiotic turnover in some colonies, resulting in reduced specificity across lineages. These results highlight how heatwaves can threaten cryptic genotypes and decouple otherwise tightly coevolved relationships between hosts and symbionts.
气候变化加剧的海洋热浪会导致基础物种大量死亡。然而，由于缺乏纵向基因组数据集，人们对于这些快速选择事件如何改变隐蔽遗传结构的理解受到了阻碍。在那些进行强制性共生的物种中，热浪的影响可能会加剧，因为多个共同进化的分类群的遗传可能会受到影响。在这里，我们通过一次长时间的热浪，对造礁珊瑚的共生关系进行了 6 年的跟踪，包括 315 个珊瑚礁中有 79 个已知的存活率。珊瑚的遗传特征强烈预测了无处不在的珊瑚（巨大的生长形式）的存活率，而在三个形态上无法区分但遗传上不同的谱系中，存活率差异很大（15%到 61%）。热浪还破坏了这些珊瑚谱系与其藻类共生体（家族 Symbiodiniaceae）之间的强烈联系，一些珊瑚礁中的共生关系发生了转变，导致谱系之间的特异性降低。这些结果强调了热浪如何威胁隐蔽基因型，并使宿主和共生体之间原本紧密共同进化的关系脱钩。
