Insights into insect wing origin provided by functional analysis of vestigial in the red flour beetle, Tribolium castaneum

Insect wings are a core example of morphological novelty, yet their acquisition remains a biological conundrum. More than a century of debates and observations has culminated in two prominent hypotheses on the origin of insect wings. Here, we show that there are two separate wing serial homologs in the wingless first thoracic segment of a beetle, Tribolium. These two tissues are merged to form an ectopic wing structure in homeotic transformation. Intriguingly, the two wing serial homologs may actually be homologous to the two previously proposed wing origins, hence supporting the dual origin of insect wings. The merger of two unrelated tissues may have been a key step in developing this morphologically novel structure during evolution.