Data from: The experimental evolution of herbicide-resistance in Chlamydomonas reinhardtii results in a positive correlation between fitness in the presence and absence of herbicides

Pleiotropic fitness trade-offs will be key determinants of the evolutionary dynamics of selection for pesticide resistance. However, for herbicide resistance, empirical support for a fitness cost of resistance is mixed, and it is therefore also questionable what further ecological trade-offs can be assumed to apply to herbicide resistance. Here, we test the existence of trade-offs by experimentally evolving herbicide resistance in Chlamydomonas reinhardtii. Although fitness costs are detected for all herbicides, we find that, counterintuitively, the most resistant populations also have the lowest fitness costs as measured by growth rate in the ancestral environment. Furthermore, after controlling for differences in the evolutionary dynamics of resistance to different herbicides, we also detect significant positive correlations between resistance, fitness in the ancestral environment and cross-resistance to other herbicides. We attribute this to the highest levels of nontarget-site resistance being achieved by fixing mutations that more broadly affect cellular physiology, which results in both more cross-resistance and less overall antagonistic pleiotropy on maximum growth rate. Consequently, the lack of classical ecological trade-offs could present a major challenge for herbicide resistance management.

多效性适合度权衡将是农药抗性选择进化动态的关键决定因素。然而，针对除草剂抗性而言，关于其抗性适合度代价的实证研究结果并不一致，因此，哪些额外的生态权衡可适用于除草剂抗性也尚存疑问。本研究通过在莱茵衣藻（Chlamydomonas reinhardtii）中实验进化出除草剂抗性，以此检验权衡效应的存在性。尽管所有除草剂均检测到了适合度代价，但我们发现，与直觉相悖的是，抗性水平最高的种群在祖先环境中的生长速率测定结果显示，其适合度代价反而最低。此外，在控制了不同除草剂抗性的进化动态差异后，我们还检测到抗性水平、祖先环境中的适合度以及对其他除草剂的交互抗性之间存在显著的正相关关系。我们将这一现象归因于：最高水平的非靶标位点抗性是通过固定那些更广泛影响细胞生理的突变实现的，这类突变既会带来更强的交互抗性，也会对最大生长速率产生更弱的拮抗多效性效应。因此，经典生态权衡的缺失可能会对除草剂抗性管理构成重大挑战。