Consequences of genome size variation in forensic entomology

Flies (Diptera) are particularly important in forensic entomology as they are primary colonizers of remains and agents of myiasis.  To successfully conduct casework, a forensic entomologist must be able to 1) accurately identify species of forensic importance and 2) know about the life histories and developmental trajectories of such flies.  Consequently, any information that can shed light on either of these factors is of potential use to a forensic entomologist.  One such variable, genome size, is currently an under-utilized tool to forensic entomologists.  Genome size evolves rapidly, such that sister species can have significantly different genome sizes.  This means that genome size information can assist in species identifications, especially when dealing with morphologically similar taxa.  Further, sexual dimorphism in genome size is observed in some species and we have taken advantage of this factor to evaluate sexual dimorphism in immature development.  Finally, genome size variation has been connected to inter-specific variation in development times.  We have conducted a survey of 200 inbred lines of Drosophila melanogaster, revealing that intra-specific variation in genome size not only correlates with two forensically important phenotypes (development rate and body size), but that it does so in an environmentally specific manner.  We present our recent research on inter- and intra- specific variation in genome sizes of forensically important and model system flies and discuss the relevance of genome size variation to three aspects of forensic investigations: species identification, sexual dimorphic development, and intra-specific variation in development.  Each of these factors can contribute to error in casework, thus the incorporation of genome size analyes into forensic entomology is one way of decreasing error in investigations.  Doing so addresses concerns raised by the National Research Council in 2009.