Phylogenetic analysis of forensically important Lucilia flies based on cytochrome oxidase I sequence: a cautionary tale for forensic species determination

Forensic scientists are increasingly using DNA to identify the species of a tissue sample. However, little attention has been paid to basic experimental design issues such as replication and the selection of taxa when designing a species diagnostic test. We present an example using the forensically important fly genus Lucilia in which an increasingly larger sample size revealed that species diagnosis based on the commonly used cytochrome oxidase I gene (COI) was less straightforward than we initially thought. This locus may still be useful for diagnosing Lucilia specimens, but additional knowledge other than the genotype will be required to reduce the list of candidate species to include only forms that can be distinguished by COI. We believe that these results illustrate the importance of study design and biological knowledge of the study species when proposing a DNA-based identification test for any taxonomic group.