Figure 3

Four models of eyespot evolution used to identify correlated eyespots. (A) Independent constrained model, in which transition rates in an eyespot are independent of the state of the other eyespot and the origination rates for the two eyespots are set to equal; (B) independent unconstrained model, in which transition rates in an eyespot are independent of the state of the other eyespot; (C) dependent constrained model, in which the transition rates of the derived eyespot are conditional on the state of the ancestral eyespot and in which the derived eyespot may only evolve when ancestral eyespot is present (the transition rate indicated by white arrow is set to zero). (D) dependent unconstrained model, in which the derived eyespot may originate regardless of whether the ancestral eyespot is present or absent. Legend: A⁻: ancestral eyespot absent; A⁺: ancestral eyespot present; D⁻: derived eyespot absent; D⁺: derived eyespot present. In each panel, colors of arrows indicate unique rate parameters. Models increase in complexity, i.e., in the number of different rates of transition between character states (arrows of different colors) that have to be estimated from the data from left (model A; three rates) to right (model D; 6 rates).