Data from: The evolutionary dynamics of adaptive virginity, sex-allocation and altruistic helping in haplodiploid animals

In haplodiploids, females can produce sons from unfertilized eggs without mating. However, virgin reproduction is usually considered to be a result of a failure to mate, rather than an adaptation. Here we build an analytical model for evolution of virgin reproduction, sex-allocation, and altruistic female helping in haplodiploid taxa. We show that when mating is costly (e.g. when mating increases predation risk), virginity can evolve as an adaptive female reproductive strategy. Furthermore, adaptive virginity results in strongly divergent sex-ratios in mated and virgin queen nests (‘split sex ratios’), which promotes the evolution of altruistic helping by daughters in mated queen nests. However, when helpers evolve to be efficient and increase nest production significantly, virgin reproduction is selected against. Our results suggest that adaptive virginity could have been an important stepping stone on the pathway to eusociality in haplodiploids. We further show that virginity can be an adaptive reproductive strategy also in primitively social haplodiploids if workers bias the sex ratio toward females. By remaining virgin, queens are free to produce sons, the more valuable sex in a female-biased population. Our work brings a new dimension to the studies linking reproductive strategies with social evolution.

在单倍二倍体（haplodiploids）类群中，雌性个体无需交配即可通过未受精卵产生雄性后代。然而，孤雌生殖（virgin reproduction）通常被视为交配失败的结果，而非一种适应性特征。本研究构建了单倍二倍体类群中孤雌生殖、性分配以及雌性利他帮助行为的演化解析模型。研究结果表明，当交配存在代价（例如交配会提升被捕食风险）时，保持处女状态（virginity）可以作为一种适应性雌性繁殖策略演化而来。此外，适应性处女状态会导致已交配蜂王巢穴与处女蜂王巢穴之间出现显著分化的性比（即“分裂性比（split sex ratios）”），这会推动已交配蜂王巢穴中雌性后代的利他帮助行为演化。但当帮助者演化出更高效率并显著提升巢穴繁殖产出时，孤雌生殖会受到选择抑制。本研究结果表明，适应性处女状态可能是单倍二倍体类群向真社会性（eusociality）演化过程中的重要垫脚石。进一步研究发现，若工蜂（workers）将性比偏向雌性，那么在原始社会性单倍二倍体类群中，保持处女状态同样可以作为一种适应性繁殖策略。通过保持处女状态，蜂王可以自由产生雄性后代——在雌性偏倚的种群中，雄性是更具演化价值的性别。本研究为联结繁殖策略与社会演化的相关研究提供了全新视角。