The transition to asexual reproduction is frequent and widespread across the tree of life and constitutes a major life history change. Without sexual reproduction, selection on sexually selected traits is expected to be weaker or absent, allowing the decay and ultimately loss of sexual traits. In this study, we applied an experimental approach to investigate the decay of reproductive traits under asexuality in two asexual populations of the springtail Folsomia candida. Specifically, we compared several key male sexual traits of a sexual population and two distinct parthenogenetic lines. To allow direct comparisons between sexual and asexual individuals we first determined a suite of life history characteristics in the sexual F. candida population, which performs an indirect transfer of sperm packages (spermatophores).To investigate the decay of male sexual traits under asexuality we measured the size of spermatophores, quantified the amount of sperm DNA material, and tested spermatophore attractiveness to females in all three populations. The amount of sperm DNA material in the sperm droplets and the attractiveness of spermatophores were lower in the asexual lines compared to the sexual population. However, the two asexual lines differed in the extent of decay of these traits. Our results are consistent with predictions from neutral mutation accumulation theory, and thus suggest this to be the main evolutionary process underlying the decay of male traits in F. candida.

向无性繁殖的过渡在整个生命之树上很普遍且广泛，构成了主要的生活史变化。如果没有性繁殖，则对性选择的性状的选择会被削弱或缺失，从而导致性状的衰败并最终丧失。在这项研究中，我们采用了一种实验方法来研究无性繁殖条件下两个野生无性繁殖的念珠菌Folsomia candida的生殖性状的衰退。具体来说，我们比较了性人群的几个主要男性性特征和两条不同的孤雌生殖系。为了直接比较性个体和无性个体，我们首先确定了性念珠菌的一整套生活史特征。为了研究在无性状态下男性性状的衰退，我们测量了精子的大小，定量了精子DNA的数量，并测试了这三个人群中精子对女性的吸引力。与有性种群相比，无性系中无性系中精子液滴中的精子DNA物质含量和精原细胞的吸引力更低。但是，两个无性系在这些性状的衰退程度上有所不同。我们的结果与中性突变积累理论的预测一致，因此表明这是假丝酵母男性性状衰退的主要进化过程。