ABSTRACT
Sex determination is a rapidly evolving biological process controlled by differential gene expression. One family of transcription factors that initiate sex-specific gene expression and differentiation in many animal species are the Doublesex and Mab-3 (DM) domain proteins. While much is known about Doublesex-related proteins in various insect orders and commonly studied model systems, little is known about their function in basally branching arthropods. Spiders are an emerging model for molecular and evolutionary development that could fill this gap. Arachnids share an ancient whole-genome duplication providing a unique opportunity to study the effect of major genomic rearrangements on the evolution of developmental processes. In this study, we aimed to identify the repertoire of Dsx-related proteins encoded by the genome of the common house spider, Parasteatoda tepidariorum. While insects have four DM domain proteins, the P. tepidariorum genome encodes seven, indicating the possibility of duplicate retention. At least four of the DM protein genes demonstrated sex bias expression in adult spiders. Embryonic expression of these genes suggests roles in development of the spinnerets, nervous system, and appendages.