Genes as Markers of Sex for Forensic Entomology

Calliphoridae is a large family of insects, and contains species Lucilia sericata (Diptera: Calliphoridae) (Meigen), Cochliomyia macellaria (Diptera: Calliphoridae) (Fabricius) and Chrysomya rufifacies (Diptera: Calliphoridae) (Macquart). These species are important medically and economically, and are commonly used in forensic investigations. In forensics, development data for species is used to predict time of colonization (TOC) estimates. However, there is sexual dimorphism in blow fly development and it is poorly understood. The difference in physical traits, as well as gene expression, may result in development disparities between sexes. For this reason, it is important to optimize a sex identification assay to aide in predicting more accurate TOC intervals for L. sericata, C. macellaria and C. rufifacies. Sex determination is an important assignment made in development. In the case of calliphorids, most undergo transformer (tra) splicing and resulting doublesex (dsx) splicing gives rise to downstream sex-specific characteristics. This may cause differing development in males and females leading to imprecise TOC estimates when not accounted for. Using known primer sets for tra and dsx, an assay for sex identification can be optimized. The newfound information on sex, in combination with published transcriptomes, can result in sex-specific interpretation of gene expression, yielding more accurate data sets for species

Patterns and Processes in the Evolution of Sequence Classes and Genomic Compartments

The content of genomes can be categorized into different sequence classes: autosomes and sex chromosomes, coding and noncoding, and repetitive and non-repetitive, to name but a few. Each of these classes of the genome has unique mechanisms that govern their evolution. In my dissertation work, I studied the evolution of the genome on three scales. My first dissertation project sought to understand the sequence class of microsatellites. For this project, I analyzed microsatellite content in all sequenced insect genomes and potential predictors of microsatellite content and rates of evolution. For my following two projects, I assessed the stability of genomes at the chromosome level. First, I assessed this stability in insects by investigating their tolerance to rearrangements dependent on the type of centromeres they possess. Next, I assessed this stability in carnivores by comparing species with small or large range sizes. For my last project, I synthesize all recorded sex chromosome systems across the tree of life and explore what we can learn from the paucity of univalent sex chromosome systems. Each of these projects adds to the understanding of genome structure and the mechanisms by which specific classes of the genome evolve