Data from: Biochemical evolution in response to intensive harvesting in algae: evolution of quality and quantity

Evolutionary responses to indirect selection pressures imposed by intensive harvesting are increasingly common. While artificial selection has shown that biochemical components can show rapid and dramatic evolution, it remains unclear as to whether intensive harvesting can inadvertently induce changes in the biochemistry of harvested populations. For applications such as algal culture, many of the desirable bioproducts could evolve in response to harvesting, reducing cost-effectiveness, but experimental tests are lacking. We used an experimental evolution approach where we imposed heavy and light harvesting regimes on multiple lines of an alga of commercial interest for twelve cycles of harvesting and then placed all lines in a common garden regime for four cycles. We have previously shown that lines in a heavy harvesting regimes evolve a ‘live fast’ phenotype with higher growth rates relative to light harvesting regimes. Here, we show that algal biochemistry also differs between regimes, though they were temporarily masked by differences in density under those different regimes. Heavy harvesting regimes, evolved lower productivity of desirable bioproducts, particularly fatty acids relative to light harvesting regimes. We suggest that commercial operators wishing to maximise productivity of desirable bioproducts should maintain mother cultures, kept at higher densities (which tend to select for desirable phenotypes), and periodically restart their intensively harvested cultures to minimise the negative consequences of biochemical evolution. Our study shows that the burgeoning algal culture industry should pay careful attention to the role of evolution in intensively harvested crops as these effects are nontrivial if subtle.

集约化收获所施加的间接选择压力引发的进化响应日益普遍。尽管人工选择研究已证实生物化学组分可发生快速且显著的进化，但目前仍不清楚集约化收获是否会无意间诱导收获种群的生物化学特性发生改变。在藻类培养等应用场景中，诸多具有经济价值的生物产物可能会因收获压力发生进化，进而降低生产的成本效益，但相关实验验证仍较为匮乏。本研究采用实验进化（experimental evolution）方法，对一种具有商业价值的藻类的多个品系施加重、轻两种收获制度，历经12轮收获循环后，将所有品系置于同质园（common garden）培育制度下培养4轮。我们此前的研究已证实，相较于轻收获制度，重收获制度下的品系进化出了‘快速生活史’表型，生长速率更高。本研究进一步发现，尽管不同收获制度下的种群密度差异曾暂时掩盖了相关差异，但两种制度下藻类的生物化学特性仍存在显著不同。重收获制度下的品系，其目标生物产物的产量出现下降，相较于轻收获制度，这一现象在脂肪酸类产物中尤为突出。我们建议，若商业运营者希望最大化目标生物产物的产量，应保留高密度培养的母种培养物（此类环境往往会筛选出符合需求的表型），并定期重启集约化收获的培养体系，以减轻生物化学进化带来的负面影响。本研究表明，蓬勃发展的藻类培养产业应高度关注集约化收获作物的进化效应——尽管此类效应可能较为细微，但其影响绝非无足轻重。