Data from: Diversification in temporally heterogeneous environments: effect of the grain in experimental bacterial populations.

Although theory established the necessary conditions for diversification in temporally heterogeneous environments, empirical evidence remains controversial. One possible explanation is the difficulty of designing experiments including the relevant range of temporal grains and the appropriate environmental tradeoffs. Here, we experimentally explore the impact of the grain on the diversification of the bacterium Pseudomonas fluorescens SBW25 in a temporally fluctuating environment by including twenty different pairs of environments and four temporal grains. In general, higher levels of diversity were observed at intermediate temporal grains. This resulted in part from the enhanced capacity of disruptive selection to generate negative genotypic correlations in performance at intermediate grains. However, the evolution of reciprocal specialization was an uncommon outcome. Although temporal heterogeneity is in theory less powerful than spatial heterogeneity to generate and maintain diversity, our results show that diversification under temporal heterogeneity is possible provided appropriate environmental grains.尽管理论研究已确立了时间异质性环境下物种多样化的必要条件，但现有实证证据仍颇具争议。一种可能的解释在于，难以设计出涵盖相关时间粒度（temporal grains）范围与恰当环境权衡（environmental tradeoffs）关系的实验方案。本研究通过设置20组不同的环境配对与4种时间粒度（temporal grains），在时变波动环境中开展实验，探究了时间粒度对荧光假单胞菌（Pseudomonas fluorescens SBW25）物种多样化的影响。总体而言，中等时间粒度环境中的物种多样性水平更高。该现象在一定程度上源于：中等时间粒度条件下，歧化选择（disruptive selection）可更强地诱导性能表现产生负基因型相关性（negative genotypic correlations）。但互惠特化（reciprocal specialization）的演化并非常见结果。尽管理论上，时间异质性在产生与维持物种多样性方面的效力弱于空间异质性（spatial heterogeneity），但本研究结果表明：只要选择恰当的环境时间粒度，时间异质性环境下的物种多样化完全可行。