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Access Type

WSU Access

Date of Award

January 2019

Degree Type

Thesis

Degree Name

M.S.

Department

Biological Sciences

First Advisor

Aleksandar Popadic´

Abstract

Exploitation of land and thereafter air are few of the triumphs that distinguish insects from other arthropods. Although we have a great understanding of the structures that allowed exploitation of these major niches, our understanding of the genetic mechanisms governing their development and diversification remains nascent. This works augments this area by investigating the genetic basis behind morphological diversity of the respiratory system and forewing morphology utilizing the milkweed bug (Oncopeltus fasciatus). Primarily, we find that change in the activity of trachealess (trh) and Abdominal-B (Abd-B) is responsible for the positional changes of the epidermal spiracles in two insect orders. Moreover, the trunk Hox gene Antennapedia (Antp) activates trh and modifies ventral veinless (vvl) to form trachea in lieu of glands. Combined with findings in crustaceans, our results demonstrate a developmental relationship between glandular structures and respiratory organs in aquatic and terrestrial arthropods. Finally, we find that apterous (ap), a key gene in the wing regulatory network, is co-opted to function in modifying the forewings from the hindwings and contributing to the evolution of hemipteran hemelytra. Collectively, these results uncover the genetic basis for the diverse organization and morphology of the tracheal system and wings, two critical traits that contributed to insect evolutionary success.

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