“…QuĂ©rĂ© et al. (2012) suggested that WEM was possibly a âhybrid swarm.â One of those features is the observation of increased fitness that should allow for ecological success to translate into evolutionary success (see, e.g., Pereira et al., 2014 for a marine example)âwhich could reflect adaptive introgression promoting the maintenance of hybrids (Hedrick, 2013; Martin, Bouck, & Arnold, 2006). Patterns of survival of the WEM Ă WEM cross go against high fitness of these âhybrids.â Adaptive introgression patterns or âswarmingâ at the center of the distribution of parental forms seems relatively common in other fish species (e.g., MachadoâSchiaffino, Juanes, & GarciaâVazquez, 2010; Roques, SĂ©vigny, & Bernatchez, 2001; Sinama et al., 2013; Stemshorn, Reed, Nolte, & Tautz, 2011; Walters et al., 2008).…”