Hybridization may increase the probability of adaptation to extreme stresses. This advantage could be caused by an increased genome plasticity in hybrids, which could accelerate the search for adaptive mutations. High ultraviolet (UV) radiation is a particular challenge in terms of adaptation because it affects the viability of organisms by directly damaging DNA, while also challenging future generations by increasing mutation rate. Here we test whether hybridization accelerates adaptive evolution in response to DNA damage, using yeast as a model. We exposed 180 populations of hybrids between species (Saccharomyces cerevisiae and Saccharomyces paradoxus) and their parental strains to UV mimetic and control conditions for approximately 100 generations. Although we found that adaptation occurs in both hybrids and parents, hybrids achieved a lower rate of adaptation, contrary to our expectations. Adaptation to DNA damage conditions comes with a large and similar cost for parents and hybrids, suggesting that this cost is not responsible for the lower adaptability of hybrids. We suggest that the lower adaptive potential of hybrids in this condition may result from the interaction between DNA damage and the inherent genetic instability of hybrids.

中文翻译：

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种间杂种在 DNA 损伤条件下表现出适应性潜力降低


杂交可以增加适应极端压力的可能性。这种优势可能是由于杂交体中基因组可塑性的增加造成的，这可以加速对适应性突变的寻找。高紫外线 (UV) 辐射在适应方面是一个特殊的挑战，因为它通过直接破坏 DNA 来影响生物体的生存能力，同时也会通过增加突变率来挑战子孙后代。在这里，我们使用酵母作为模型来测试杂交是否加速了针对 DNA 损伤的适应性进化。我们将 180 个物种（酿酒酵母和奇异酵母）及其亲本菌株之间的杂交种群暴露在紫外线模拟和对照条件下大约 100 代。尽管我们发现杂种和亲本都发生了适应，但杂种的适应率较低，这与我们的预期相反。适应 DNA 损伤条件对亲本和杂种来说都会带来巨大且相似的成本，这表明这种成本并不是杂种适应性较低的原因。我们认为，在这种情况下，杂交种的适应性潜力较低可能是由于 DNA 损伤和杂交种固有的遗传不稳定性之间的相互作用造成的。