We seek to explain that the evolution of the format of televised presidential debates –in each country– is determined by the interaction between the specific characteristics of the political system and the media system. As a framework, we use Anstead’s (2016) application of the concept of speciation to the evolution of debates in parliamentary systems, together with Strömbäck’s (2008) scheme for the evolution of mediatization. We applied this scheme to the Chilean case, and we concluded that the original model used –the same one that the United States used until the mid-1990’s– evolved to adapt to a multi-party presidential system and a commercial television system.