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.

集约化采收（intensive harvesting）所施加的间接选择压力引发的进化响应正日益普遍。尽管人工选择研究已证实生物化学成分可发生快速且显著的进化，但目前仍不清楚集约化采收是否会无意中引发采收种群的生物化学特征改变。对于藻类培养这类应用场景而言，诸多目标生物产物（bioproducts）可能会随采收过程发生进化，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，对多株具有商业价值的藻类品系施加重度和轻度两种采收制度，历经12轮采收周期后，将所有品系置于同质园（common garden）处理制度下培养4轮周期。我们此前的研究已证实，相较于轻度采收制度组，重度采收制度组的品系进化出了更快的生长速率，即“快速生活史（live fast）”表型。本研究进一步发现，不同采收制度组的藻类生物化学特征同样存在差异，不过该差异曾暂时被不同制度下的种群密度差异所掩盖。相较于轻度采收制度组，重度采收制度组的目标生物产物产量更低，尤以脂肪酸类产物为甚。我们建议，若希望最大化目标生物产物的产量，商业经营者应保留以较高密度培养的母种培养物——这类培养物通常会定向选择保留目标表型——并定期重启集约化采收的培养体系，以尽可能降低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重视进化在集约化采收养殖藻类中的作用，尽管这类效应看似细微，实则不容忽视。