Award Date

December 2023

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Life Sciences

First Committee Member

Donald Price

Second Committee Member

Mira Han

Third Committee Member

Jeffery Shen

Fourth Committee Member

Melissa Carrion

Number of Pages

72

Abstract

The olfactory system is a powerful tool for sensing countless odorants. In Drosophila, the olfactory system is critical for detecting food, finding mates, laying eggs, avoiding predators, and adapting to new environments. Understanding the olfactory system in Drosophila will advance our knowledge of sensory biology in various insects and vertebrates, including humans. Drosophila has been a valuable model for biology since the early 1900s, and the Drosophila melanogaster olfactory system is well-studied. The Hawaiian Drosophila represent approximately 1/3 of the world’s Drosophila, however, there is limited research on Hawaiian Drosophila olfactory genes. We conducted a comparative analysis of olfactory receptor (OR) genes in four Hawaiian Drosophila and five non-Hawaiian Drosophila species. The four Hawaiian Drosophila (Drosophila silvestris, Drosophila basisetae, Drosophila grimshawi, and Drosophila sproati) were sequenced, assembled, and annotated, while five non-Hawaiian Drosophila species (Drosophila melanogaster, Drosophila simulans, Drosophila yakuba, Drosophila virilis, and Drosophila mojavensis) served as outgroup species. Notably, about 40 out of the 60 OR genes in Drosophila melanogaster were found to be conserved across most Hawaiian Drosophila species. Several genes experienced a high number of positive selection sites, including OR2a, Or46a, OR67a, OR69a, OR71a, OR85f, OR88, and OR92a, which are vital for various functions such as reproduction, oviposition, and detecting food sources and threats. No extreme negative selection was observed among the detected OR genes. There were some differences in OR gene expression between females and males and among different Hawaiian Drosophila species. The changes in OR gene sequences between Hawaiian Drosophila species and differential gene expression indicate that the olfactory system has evolved differences in chemosensory responses between species and sexes. Our study enhances the comprehensive knowledge of sensory biology and the evolutionary patterns of olfactory receptors, providing valuable insights into the distinctive adaptations of Hawaiian Drosophila.

Keywords

Evolution; Gene expression; Gene expression; Hawaiian Drosophila; Natural selection; Olfactory receptor genes

Disciplines

Bioinformatics | Biology

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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