Rapid comeback of males: evolution of male-killer suppression in a green lacewing population

Evolutionary theory predicts that the spread of cytoplasmic sex ratio distorters leads to the evolution of host nuclear suppressors, although there are extremely few empirical observations of this phenomenon. Here, we demonstrate that a nuclear suppressor of a cytoplasmic male killer has spread rapidly in a population of the green lacewing Mallada desjardinsi. An M. desjardinsi population, which was strongly female-biased in 2011 because of a high prevalence of the male-killing Spiroplasma endosymbiont, had a sex ratio near parity in 2016, despite a consistent Spiroplasma prevalence. Most of the offspring derived from individuals collected in 2016 had 1:1 sex ratios in subsequent generations. Contrastingly, all-female or female-biased broods appeared frequently from crossings of these female offspring with males derived from a laboratory line founded by individuals collected in 2011. These results suggest near-fixation of a nuclear suppressor against male killing in 2016 and reject the ...进化理论预测，细胞质性别比例操纵因子（cytoplasmic sex ratio distorters）的扩散会驱动宿主核抑制因子（nuclear suppressors）的演化，但目前针对该现象的实证观测极为匮乏。本研究证实，一种可抑制细胞质雄性杀手（cytoplasmic male killer）的核抑制因子，已在绿色草蛉（Mallada desjardinsi）的种群中快速扩散。2011年，由于雄杀性螺原体（Spiroplasma）内共生体（endosymbiont）的高感染率，该种群性别比例严重偏雌；而到2016年，尽管螺原体的感染率仍保持稳定，种群性别比例已趋近于1:1。2016年采集的个体所产生的多数子代，在后续世代中均呈现1:1的性别比例。与之形成鲜明对照的是，将这些2016年采集的雌性子代与2011年采集个体建立的实验室品系（laboratory line）雄性个体进行杂交时，全雌或偏雌的子代窝频繁出现。上述结果表明，2016年时针对雄杀作用的核抑制因子已接近固定，并否定了……