A Rose by Any Other Name: Establishing the Evolutionary Origin for a "Unique" Reproductive Organ

The bursa copulatrix is an organ found within the reproductive tract of female butterflies and moths. The bursa presents as an outcropping of the reproductive tract and possesses teeth-like structures. It acts to accept and digest the complex male ejaculate and is intricately linked to the battle over female remating rate, fecundity, and paternity. Multiple insect species possess a similar organ, though parallels had not been previously established. Despite some of the female-specific organs possessing the same name and others their own unique classifier, it was unknown whether these organs stemmed from a single evolutionary origin or whether they represented convergent traits. We examined the scientific literature to determine whether there was evidence for the existence of a bursa-like organ within the female reproductive tract for each family of insects. These classifications were then used in an ancestral state reconstruction analysis and identified multiple possible evolutionary origins for the bursa across insects. These results can be used to predict the functions and characteristics in the understudied systems and to make large-scale conclusions about the patterns of female-mediated reproductive outcomes.