Phenotypic heterogeneity as a strategy for speeding up adaptive evolution at minimal cost

枯草芽孢杆菌在固定生长期表现出表型变异性。特别地，一个明确定义的等基因细胞的部分分化成转化能力的状态。在这里，我们讨论的问题是，这种类型的行为是否最优，以加快适应，同时最小化能力发展的成本。我们将在枯草芽孢杆菌中产生以不同速率分化的突变体，并使用一种使整个种群确定性地进入能力状态的菌株。我们计划进行进化实验来量化这些不同能力控制策略的适合度增长率。我们将特别讨论以下具体问题：加速适应的能力差异化的最佳速度和策略是什么？这些比率和策略如何取决于突变率？遗传漂变如何影响分化的最佳速率？由于分化和转化的分子细节得到了很好的表征，因此本项目获得的适应率可以作为重组控制策略数学建模的基础。这些结果将加深我们对表型变异的生物学意义的理解。

Bacillus subtilis shows phenotypic variability in the stationary growth phase. In particular, a well-defined fraction of isogenic cells differentiates into the state of competence for transformation. Here we address the question whether this type of behaviour is optimal to speed up adaptation while minimizing the cost of competence development. We will generate mutants in B. subtilis which differentiate at different rates, and use a strain in which the entire population deterministically enters the state of competence. We plan to perform evolution experiments to quantify the rate of fitness increase for these different strategies of competence control. In particular we will address the following specific questions: What is the optimum rate and strategy of competence differentiation for speeding up adaptation? How do these rates and strategies depend on mutation rates? How does genetic drift affect the optimum rate of differentiation? Since the molecular details of differentiation and transformation are well characterized, the adaptation rates obtained from this project can serve as a basis for mathematical modelling of recombination control strategies. The results will deepen our understanding of the biological significance of phenotypic variability.