Sexual selection does not drive hindwing tail elaboration in a moon moth, Actias luna

The most emblematic animal traits are often attributed to sexual selection. While this pressure is an important force, elaborated traits that have been driven solely by natural selection are less enumerated. Here, we test an elaborate trait that has been studied in an anti-predator context, but that remains unstudied for its role in mating. We gave female Actias luna (Saturniidae) moths a choice between two males of differing hindwing tail treatments. In our primary experiment, males with intact tails garnered more matings than males with tails removed, but this difference appears to result from damage incurred by tail removal. We verified this with a series of additional experiments: we created a tail/no-tail dyad where we removed tails from both males, then reglued tails to one and applied glue to the hindwings of the other. We found no difference in mating success. To ensure that this no-difference result was not due to the glue itself, we offered females two intact males, with glue added to the wings of one. This dyad also had equal mating success. We therefore find no evidence that tails play a role in sexual selection. These results, in combination with previous research on bat-moth battles using A. luna, leads us to conclude that hindwing tail elaboration was likely driven by natural selection alone. We suggest that future research testing multiple selective forces on animal traits is needed to reveal the prevalence of natural versus sexual selection as the primary force driving trait elaboration in diverse animal taxa.