Rapid compensatory evolution can rescue low fitness symbioses following partner switching.
Rapid compensatory evolution can rescue low fitness symbioses following partner switching.
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快速补偿进化可以挽救伴侣转换后的低适应度共生体。
DOI：
10.1016/j.cub.2021.06.034
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Sørensen MES
中科院分区：
文献类型：
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作者：
Sørensen MES
伙伴转换在共生进化中发挥着重要作用，使本地能够适应并从共生崩溃中恢复过来。由于基因组间的上位性，伴侣转换共生体可能具有新的表型组合，但也可能表现出低适应性，由于他们缺乏最近的共同进化历史。在这里，我们研究了草履虫-小球藻共生中基因组间上位性的结构和机制，并测试了补偿性进化是否可以拯救最初的低适应性伴侣转换共生。使用合作伙伴开关实验加上代谢组学，我们显示的证据，基因组间上位性，其中低健身与升高共生体的压力反应，无论是在黑暗或高辐照度的环境，可能是由于不匹配的光管理性状之间的主机和共生体基因型。在强光条件下的实验进化表明，最初的低健身合作伙伴切换非本地主机共生配对迅速适应，获得健身相当于本地主机共生配对在不到50代主机。补偿性进化有两种途径：宿主进化出更高的共生体负荷以缓解新藻共生体的不良表现，或者藻共生体自身进化出更高的光合作用和光保护特性投资以更好地缓解光胁迫。这些研究结果表明，伙伴转换结合快速补偿性进化，可以使共生体的恢复和局部适应，以应对不断变化的环境。
Partner switching plays an important role in the evolution of symbiosis, enabling local adaptation and recovery from the breakdown of symbiosis. Because of intergenomic epistasis, partner-switched symbioses may possess novel combinations of phenotypes but may also exhibit low fitness due to their lack of recent coevolutionary history. Here, we examine the structure and mechanisms of intergenomic epistasis in theParamecium-Chlorellasymbiosis and test whether compensatory evolution can rescue initially low fitness partner-switched symbioses. Using partner-switch experiments coupled with metabolomics, we show evidence for intergenomic epistasis wherein low fitness is associated with elevated symbiont stress responses either in dark or high irradiance environments, potentially owing to mismatched light management traits between the host and symbiont genotypes. Experimental evolution under high light conditions revealed that an initially low fitness partner-switched non-native host-symbiont pairing rapidly adapted, gaining fitness equivalent to the native host-symbiont pairing in less than 50 host generations. Compensatory evolution took two alternative routes: either hosts evolved higher symbiont loads to mitigate for their new algal symbiont's poor performance, or the algal symbionts themselves evolved higher investment in photosynthesis and photoprotective traits to better mitigate light stress. These findings suggest that partner switching combined with rapid compensatory evolution can enable the recovery and local adaptation of symbioses in response to changing environments.