Host-symbiont coevolution, cryptic structure, and bleaching susceptibility, in a coral species complex (Scleractinia; Poritidae).

We compared existing Porites data with bleached and unbleached colonies of the branching coral P. compressa collected in Kaneohe Bay Hawaii during the 2015 coral bleaching event. Loci that mapped to coral, symbiont, and microbial references revealed genetic structure consistent with recent host-symbiont co-evolution. Cryptic genetic clades were resolved that previous work has associated with distance from shore, but no genetic structure was associated with bleaching. We identified many candidate loci associated with morphospecies, including candidate host and symbiont loci with fixed differences between branching and mounding corals. We also found many loci associated with cryptic genetic structure, yet relatively few loci associated with bleaching. Recent host-symbiont co-evolution and rapid diversification suggests that variation and therefore the capacity of these corals to adapt may be underappreciated.

本研究将已公开的多孔螅属（Porites）数据，与2015年夏威夷卡内奥赫湾珊瑚白化事件期间采集的分枝型压缩多孔螅（P. compressa）的白化与非白化珊瑚群体进行对照分析。比对至珊瑚、共生体及微生物参考基因组的基因座，呈现出与近期宿主-共生体共进化模式相符的遗传结构。研究解析出以往研究中与离岸距离相关的隐蔽遗传支系，但未发现与珊瑚白化相关的遗传结构。本研究鉴定出大量与形态种相关的候选基因座，其中包含分枝型与团块型珊瑚之间存在固定遗传差异的宿主及共生体候选基因座。同时，本研究还发现大量与隐蔽遗传结构相关的基因座，但与珊瑚白化相关的基因座数量相对较少。近期的宿主-共生体共进化与快速分化现象提示，这类珊瑚的遗传变异及其环境适应能力可能被低估了。