Prior evolution in stochastic versus constant temperatures affects RNA virus evolvability at a thermal extreme
Prior evolution in stochastic versus constant temperatures affects RNA virus evolvability at a thermal extreme
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DOI：
10.1002/ece3.6287
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发表时间：
2020-04-29
影响因子：
2.6
通讯作者：
Turner, Paul E.
中科院分区：
文献类型：
--
作者：
Gloria-Soria, Andrea;Mendiola, Sandra Y.;Turner, Paul E.
目前尚不清楚历史适应与先前环境中的适应不良如何影响新栖息地的种群进化。先前的工作表明，在恒定37摄氏度进化的水泡性口炎病毒(VSV)种群在29摄氏度和37摄氏度时细胞感染都有所改善；相比之下，在29摄氏度和37摄氏度之间随机变化的温度进化的水泡性口炎病毒种群没有改善。在这里，我们测试了先前的进化是否影响了热生态位边缘的适应速度：40摄氏度。在新环境中生成40代病毒后，我们观察到历史上在随机温度下进化的种群显示出更强的适应性。深度测序显示，大多数新进化的突变是从头开始的。此外，VSV糖蛋白和复制酶基因的两个新的进化突变倾向于在先前在37摄氏度恒定进化的种群中共存，而这种平行关系在先前随机温度进化的种群中未见。这些结果表明，在恒定温度和随机温度下的先前适应限制了突变格局，这种突变格局可以改善在新的40摄氏度环境中的适应性，这可能是由于进入早先分歧的遗传结构的新突变的不同上位效应。我们得出的结论是，对以前环境不适应的RNA病毒可以比适应度更高的病毒“越级”，从而在新的环境中实现更快的适应。
It is unclear how historical adaptation versus maladaptation in a prior environment affects population evolvability in a novel habitat. Prior work showed that vesicular stomatitis virus (VSV) populations evolved at constant 37 degrees C improved in cellular infection at both 29 degrees C and 37 degrees C; in contrast, those evolved under random changing temperatures between 29 degrees C and 37 degrees C failed to improve. Here, we tested whether prior evolution affected the rate of adaptation at the thermal-niche edge: 40 degrees C. After 40 virus generations in the new environment, we observed that populations historically evolved at random temperatures showed greater adaptability. Deep sequencing revealed that most of the newly evolved mutations were de novo. Also, two novel evolved mutations in the VSV glycoprotein and replicase genes tended to co-occur in the populations previously evolved at constant 37 degrees C, whereas this parallelism was not seen in populations with prior random temperature evolution. These results suggest that prior adaptation under constant versus random temperatures constrained the mutation landscape that could improve fitness in the novel 40 degrees C environment, perhaps owing to differing epistatic effects of new mutations entering genetic architectures that earlier diverged. We concluded that RNA viruses maladapted to their previous environment could "leapfrog" over counterparts of higher fitness, to achieve faster adaptability in a novel environment.