In organisms in which individuals mate multiply, knowledge of the proportion of offspring sired by the last male to mate (P₂) under field conditions is important for a thorough understanding of how sexual selection works in nature. In many insect groups, pronounced intraspecific variation in P₂ is commonplace. Interestingly, however, in stark contrast to these observations, compilation of P₂ data in dragonflies and damselflies (Odonata) indicates that a high P₂, seldom below 0.95, is a feature of this taxon. Here we used double digest restriction-site associated DNA sequencing to generate a panel of single nucleotide polymorphisms (SNPs) with which we could determine paternity and estimate values of P₂ in the offspring of 19 field-collected pairs of the emerald damselfly Lestes sponsa. We also estimated the relationship between P₂ and male genital shape of 16 males using geometric morphometric analysis. P₂ was variable (range = 0.0–1.0; mean = 0.5), and there was a marginally non-significant (P = 0.069) relationship between genital shape and P₂, suggesting that males with a high P₂ had an aedeagus with a broader tip. We suggest that the high P₂-values reported in past studies in Odonata are partly due to the methods used to infer paternity. Use of SNPs to determine patterns of paternity and P₂ in odonates is needed for a better appraisal of fitness in odonates, and would open many future avenues for use of odonates as models of sexual selection.

中文翻译：

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祖母豆（Lestes sponsa）的最后一次男性精子优先次序和生殖器形态发生很大变化

在个体交配的生物中，了解野外条件下最后一个雄对交配的后代（P ₂）的比例的知识对于全面了解性选择在自然界的工作方式非常重要。在许多昆虫群中，P _2中明显的种内变异是司空见惯的。但是，有趣的是，与这些观察结果形成鲜明对比的是，蜻蜓和豆娘（Odonata）中P ₂数据的汇编表明，该分类群的特征是高P ₂很少低于0.95。在这里，我们使用双消化限制性位点相关的DNA测序来生成一组单核苷酸多态性（SNP），通过它我们可以确定亲子关系并估计P _2的值在19场野外采集的祖母绿Lestes sponsa的后代中。我们还使用几何形态计量学分析估计了P ₂与16位男性的男性生殖器形状之间的关系。P ₂是可变的（范围= 0.0–1.0；平均值= 0.5），并且生殖器形状与P ₂之间存在一定程度的非显着性关系（P = 0.069），这表明P ₂高的男性的食道具有更广泛的提示。我们建议在Odonata的过去研究中报道的高P _2值部分归因于推断亲子关系的方法。使用SNP确定亲子关系和P _2的模式 需要更好地评估是否适合使用卵酸盐，并为使用卵酸盐作为性选择的模型开辟了许多未来的途径。