High variation in last male sperm precedence and genital morphology in the emerald damselfly, Lestes sponsa

In organisms in which individuals mate multiply, knowledge of the proportion of offspring sired by the last male to mate (P-2) under field conditions is important for a thorough understanding of how sexual selection works in nature. In many insect groups, pronounced intraspecific variation in P-2 is commonplace. Interestingly, however, in stark contrast to these observations, compilation of P-2 data in dragonflies and damselflies (Odonata) indicates that a high P-2, 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 P-2 in the offspring of 19 field-collected pairs of the emerald damselfly Lestes sponsa. We also estimated the relationship between P-2 and male genital shape of 16 males using geometric morphometric analysis. P-2 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 P-2, suggesting that males with a high P-2 had an aedeagus with a broader tip. We suggest that the high P-2 -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 P-2 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.