“…Although repeated gene flow between sexual females and asexual males through contagious parthenogenesis would be expected to result in a regular emergence of asexual strains with diverse maternal origins, the fact that just two, possibly three, maternal origins of parthenogenetic lineages have been identified (Muñoz et al, 2010; Maniatsi et al, 2011; Maccari, Amat & Gómez, 2013) indicate that the incidence of contagious parthenogenesis, if this is the mechanism of origin, must be extremely low in natural environments. Indeed, the rare males must be present in the population at the same time as the sexual females of the related species, and given that both parthenogenetic and sexual species often have different ecological requirements, they may overlap just during part of each season (Amat et al, 1991; Ghomari et al, 2011). In addition, the percentage of rare male production by diploid parthenogenetic females is very low, about 1–16 in 1000 (Maccari et al, 2013).…”