One gene detected by wssGWAS analysis that was the most connected node was Sox2. The Sox2 gene plays a critical role in maintenance and proliferation of pluripotent and neural progenitor stem cells (Takahashi and Yamanaka, 2006; Zhang and Cui, 2014) through its interaction with transforming Growth Factor β (TGFb) signaling (Gaarenstroom and Hill, 2014), although little is known about the role of Sox2 in muscle. Albeit, TGFb ligands like myostatin inhibit muscle growth (Lee et al., 2005; Phelps et al., 2013), partially through reductions in myogenic precursor cell proliferation (Garikipati and Rodgers, 2012; Seiliez et al., 2012). Trim33 is another gene detected by wssGWAS analysis that is up-regulated during muscle regeneration in mice and appears to play a role in myoblast proliferation (Mohassel et al., 2015). Therefore, similar to Sox2, Trim33 may also contribute to maintaining a proliferating population of myogenic precursor cells throughout development in the rainbow trout. Trim33 also inhibits Smad4 (Xi et al., 2011), a transcription factor activated by TGFb signaling that inhibits muscle regeneration and maintenance of myogenesis with age (Lee et al., 2005).