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

We commonly think of elaborate traits in animals as evolving for mate acquisition. Some elaborate traits, however, have evolved from other pressures. We tested whether the elaborate hindwing tails of a moon moth is attractive to females. We offered females a choice between males with or without tails and found evidence that she does not discriminate based on this trait. Tails have likely been driven by natural selection forces rather than sexual ones. 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 in moths-hindwing tails-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. This difference appears to result from damage incurred by tail removal, however, as demonstrated with additional experiments. We created a tail/no-tail experimental set where we removed tails from both males, then reglued tails to one and applied glue only to the hindwings of the other. We found no significant difference in mating success between these males. To ensure that this result was not due to the glue itself, we offered females two intact males, with glue added to the wings of one. This set also had equal mating success. We therefore do not find evidence that tails play a role in sexual selection. These results, in combination with previous research on bat-moth battles using A. luna, indicate that the non-sexually dimorphic hindwing tail was likely driven by natural selection. We suggest that future research testing multiple selective forces is needed to reveal the prevalence of natural versus sexual selection as the primary force driving trait elaboration in diverse animal taxa.