Abstracts (first author)
Does incorporation of alarm calls into avian song increase rates of signal divergence across species?
Assortative mating of co-occurring species depends on the interaction between the evolution of signals involved in mating decisions and the corresponding recognition mechanisms. In two hybridizing Ficedula flycatcher species, both plumage characteristics and mate preferences are found on the paternally inherited Z chromosome, suggesting that assortative mating is achieved in these species through physical linkage of signals and preferences. In flycatchers, as in other songbird species, song functions not only in mate attraction, but also in interactions between males and has a learned component, leading to a series of potential problems for genetic linkage and assortative mating. Here, through experimental playbacks to Ficedula chicks from each species still in the nest, I show that chicks respond more strongly to the songs of their genetic fathers, suggesting that recognition of complex vocal signals is determined by genes on the Z chromosome. In contrast, chicks respond readily to the innately produced alarm calls of the other species, suggesting that recognition of vocal signals is achieved through mechanisms that are independent from how they are transmitted.