Elucidation of the genetic basis of monogeny in Chrysomya rufifacies (Diptera: Calliphoridae)

Though Drosophila spp. are exemplary model organisms, research suggests that they possess a derived sex-determination pathway relative to other Diptera.  As researchers work to identify models of sex-determination pathway cascade evolution, discernment of these patterns in other species becomes vital.  Chrysomya rufifiacies (Diptera: Calliphoridae) is an invasive blow fly in the New World.  Unlike other flies which have heteromorphic sex chromosomes and a sex-determination system based on embryonic genotype, Ch. rufifacies has homomorphic sex chromosomes and a monogenic system of sex determination in which the sex of her offspring is a phenotype of the mother.  Based on linkage, tissue exchange, and protein mapping studies, female-producing (thylegenic) females are heterozygote-dominant for an unidentified protein produced in the ovaries and incorporated into the soma of the eggs that predetermines the sex of the offspring.  At present, hybridization studies have suggested the presence of only sex-lethal and daughterless homologues in this species. A de novo transcriptome assembly was completed to compare patterns of gene expression between males, male-producing (arrhenogenic) females, and thylegenic females.  The impact of these findings to the evolution of sex determination and application to the forensic field will be discussed.