Doctor of Philosophy, Miami University, 2018, Biology

The acquisition of wings was a defining moment in the evolution of insects. The novel insect wing provided insects with the ability to disperse via powered flight and with an evolutionary medium for the emergence of new traits, both of which have greatly contributed to the success of this clade. However, despite the importance of insect wings, the evolutionary origin of this structure remains a mystery. Historically, the origin of the insect wing has captivated scientists and, accordingly, it has been debated for over 200 years. Over the course of these debates, two possible wing origin tissues have been identified; a lateral outgrowth of the dorsal body wall (tergum) and ancestral proximal leg structures (pleuron in insects). However, there is still no consensus as where insect wings came from and how they have evolved. This dissertation aims to address this conundrum through the identification of wing-related structures in the wingless segments of insects (wing serial homologs) and in non-winged arthropods. The identification of structures related to wings in wingless segments can give us a better understanding of the ancestral state of the tissues that gave rise to the insect wing and provide us with a more comprehensive view of wing evolution. In the first study, we identified wing serial homologs in the wingless first thoracic segment (T1) of the beetle, Tribolium. Through our analyses, we determined that T1 of Tribolium possesses two separate wing serial homologs, one tergal and one pleural. This study provided the first functional evidence for a dual origin of insect wings, which unifies the two previous hypotheses and suggests that insect wings are formed from a merger of both tergal and pleural tissues. In the second study, to gain a better understanding of the evolutionary contribution of each of these tissues to the wing, we analyzed how each of the Tribolium T1 wing homologs contributes to a wing formed in the traditionally wingless T1 upon Hox reduction (open full item for complete abstract)

Committee: Yoshinori Tomoyasu (Advisor) Subjects: Biology; Evolution and Development