Data from: Life-history evolution and density-dependent growth in experimental populations of yeast

We studied the evolution of the correlation between growth rate r and yield K in experimental lineages of the yeast Saccharomyces cerevisiae. First, we isolated a single clone every ~250 generations from each of eight populations selected in a glucose-limited medium for 5000 generations at ~6.6 population doublings per day (20 clones per line × 8 lines) and measured its growth rate and yield in a new, galactose-limited medium (with ~1.3 doubling per day). For most lines, r on galactose increased throughout the 5000 generations of selection on glucose while K on galactose declined. Next, we selected these 160 glucose-adapted clones in the galactose environment for ~120 generations and measured changes in r and K in galactose. In general, growth rate increased and yield declined, and clones that initially grew slowly on galactose improved more than did faster clones. We found a negative correlation between r and K among clones both within each line and across all clones. We provide evidence that this relationship is not heritable and is a negative environmental correlation rather than a genetic trade-off.

本研究针对酿酒酵母（Saccharomyces cerevisiae）实验演化谱系内生长速率r与产量K的相关性演化展开探究。首先，我们从8个在葡萄糖限制培养基中、以每日约6.6次群体倍增的速率进行5000世代选择的种群中，每约250世代分离1个单克隆（每个谱系20个克隆，共8个谱系，总计160个克隆），并在一种新的半乳糖限制培养基（每日倍增速率约1.3次）中测定其生长速率与产量。对于多数谱系而言，在葡萄糖选择条件下的5000世代中，其在半乳糖培养基上的生长速率r持续升高，而产量K则逐步下降。随后，我们将这160株已适应葡萄糖环境的克隆置于半乳糖环境中进行约120世代的传代培养与选择，并测定其在半乳糖培养基中r与K的变化幅度。总体而言，生长速率呈上升趋势而产量持续下降，且初始在半乳糖培养基上生长较慢的克隆，其性能提升幅度显著高于初始生长较快的克隆。我们发现，无论是在单个谱系内部还是所有克隆之间，r与K均存在显著负相关关系。本研究提供实验证据表明，该相关性并非可遗传的性状关联，而是一种负向环境相关性，而非遗传权衡（genetic trade-off）。