Phylogenetic evidence for colour pattern convergence in toxic pitohuis: Mullerian mimicry in birds?

Bird species in the genus Pitohui are chemically defended by a potent neuro toxic alkaloid in their skin and feathers. The two most toxic pitohui speci es, the hooded pitohui (Pitohui dichrous) and the variable pitohui (Pitohui kirhocephalus), are sometimes strikingly patterned and, in certain portion s of their geographical ranges, both species share a nearly identical colou r pattern, whereas in other areas they do not. Mullerian mimicry (the mutua l resemblance of two chemically defended prey species) is common in some ot her animal groups and Pitohui birds have been suggested as one of the most likely cases in birds. Here, we examine pitohui plumage evolution in the co ntext of a well-supported molecular phylogeny and use a maximum likelihood approach to test for convergent evolution in coloration. We show that the ' mimetic' phenotype is ancestral to both species and that the resemblance in most races is better explained by a shared ancestry. One large clade of P kirhocephalus lost this mimetic phenotype early in their evolution and one race nested deep within this clade appears to have re-evolved this phenotyp e. These latter findings are consistent with the hypothesis that Mullerian mimicry is driving the evolution for a similar colour pattern between P dic hrous, but only in this one clade of R kirhocephalus.