Adaptation of Escherichia coli to glucose promotes evolvability in lactose
Adaptation of Escherichia coli to glucose promotes evolvability in lactose
复制标题
DOI：
10.1111/evo.12849
复制
发表时间：
2016-02-01
期刊：
影响因子：
3.3
通讯作者：
Cooper, Tim F.
中科院分区：
文献类型：
--
作者：
Phillips, Kelly N.;Castillo, Gerardo;Cooper, Tim F.
一个种群的选择性历史可以影响其随后的进化，这种效应被称为历史偶然性。我们先前观察到，在葡萄糖限制的环境中进化了2000代，然后转向乳糖1000代的6个重复种群中有5个在乳糖中的适应性增加比直接从祖先开始的种群更高。为了测试葡萄糖的选择是否系统地增加乳糖进化性，我们开始了12个重放群体，其中6个来自群体子样本，6个来自6个葡萄糖进化的创始人群体中的每一个的单个随机选择的克隆。这些重放种群和18个祖先种群在乳糖限制的环境中进化了1000代。我们发现，重放种群最初在乳糖中的适应性略低于祖先，但更具有进化性，因为它们以更快的速度和更高的水平增加了适应性。这一结果表明，葡萄糖环境中的进化导致了遗传变化，增加了基因型适应乳糖的潜力。基因组测序确定了四个genesiclR，nadR，spoT，和rbs的突变，在大多数葡萄糖进化的克隆，是候选人介导的进化增加。我们的研究结果表明，在一个环境中选择过程中的短期选择成本可以导致可进化性的变化，从而带来更长期的利益。
The selective history of a population can influence its subsequent evolution, an effect known as historical contingency. We previously observed that five of six replicate populations that were evolved in a glucose-limited environment for 2000 generations, then switched to lactose for 1000 generations, had higher fitness increases in lactose than populations started directly from the ancestor. To test if selection in glucose systematically increased lactose evolvability, we started 12 replay populationssix from a population subsample and six from a single randomly selected clonefrom each of the six glucose-evolved founder populations. These replay populations and 18 ancestral populations were evolved for 1000 generations in a lactose-limited environment. We found that replay populations were initially slightly less fit in lactose than the ancestor, but were more evolvable, in that they increased in fitness at a faster rate and to higher levels. This result indicates that evolution in the glucose environment resulted in genetic changes that increased the potential of genotypes to adapt to lactose. Genome sequencing identified four genesiclR, nadR, spoT, and rbsthat were mutated in most glucose-evolved clones and are candidates for mediating increased evolvability. Our results demonstrate that short-term selective costs during selection in one environment can lead to changes in evolvability that confer longer term benefits.