Genetic conflict and changes in heterogametic mechanisms of sex determination

Abstract

The consequences of cytoplasmic sex-ratio distortion and host repression for the evolution of host sex-determining mechanisms are examined. Analytical models and simulations are developed to investigate whether the interplay between sex-ratio distorters and host masculinizers or resistance genes can cause heterogamety switching (changes between male and female heterogamety). Switches from female heterogamety to a system analogous to male heterogamety can occur when selection favours the spread of autosomal masculinizers. However, the evolutionary outcome depends on the type of repressor and costs associated with repression, and also on aspects of population structure. Under most conditions, systems evolved to a polymorphic sex-determining state although many systems were characterized by numerical dominance of male heterogamety.