Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Department

Biology

First Advisor's Name

Jeffrey Wells

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

DeEtta Mills

Second Advisor's Committee Title

Committee Member

Third Advisor's Name

Aaron Tarone

Third Advisor's Committee Title

Committee Member

Fourth Advisor's Name

Jamie Theobald

Fourth Advisor's Committee Title

Committee Member

Fifth Advisor's Name

Changwon Yoo

Fifth Advisor's Committee Title

Committee Member

Keywords

Biology

Date of Defense

10-26-2016

Abstract

A very unique compound eye in dipterans is found in males of the forensically important blow fly, Chrysomya megacephala (Diptera: Calliphoridae). This compound eye is characterized by an area of enlarged dorsal facets that, unlike almost all other regional changes in dipteran ommatidia size, is not accompanied by a change in resolution. This region is believed to play a role in mate tracking and allow for increased light capture, though no behavioral studies have tested these claims. An initial goal of the dissertation was to examine the function of this compound eye. Using allometric measurements coupled with behavioral tests, I found larger males had larger eyes and proportionally more dorsally enlarged facets. This finding suggested that larger individuals would move at lower light levels. When comparing similar sized male and females, however, body size and not the specialized male dorsal region dictated the light level at which movement occurred.

A second focus of this dissertation was the development of tools to understand how the male compound eye is genetically regulated. The male-specific enlarged dorsal ommatidia offer a model for understanding how a gross morphological difference of a feature present in both sexes can arise when much of the same genetic content is shared. Since the genes regulating compound eye development are mainly expressed during stages when sex cannot be efficiently determined, I first designed a molecular test for identifying sex by amplifying a region of the transformer gene differentially spliced by sex in blow flies from other genera. Then, I was able to compare temporal patterns of gene expression for rhodopsin genes in separate sexes for the first time in blow flies, which allowed for an initial investigation into the expression patterns influencing the development of the male compound eye.

Apart from the biological significance regarding a unique compound eye, the forensic importance of C. megacephala means that information obtained in this dissertation can be utilized by forensic investigators. The work on low light level movement adds to the understanding of nocturnal oviposition patterns and the ability to sex immature specimens allows for the determination of sex specific development rates.

Identifier

FIDC001174

Available for download on Sunday, December 03, 2017

Included in

Biology Commons

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