Species-specific song convergence in a moving hybrid zone between two passerines

摘要: Moving hybrid zones are receiving increasing attention. However, so far little is known about the proximate mechanisms underlying these movements. Signalling behaviour, by individuals engaged in interspecific sexual and aggressive interactions, may play a crucial role. In this study, we investigated song variation within moving zone between two warblers, Hippolais polyglotta H. icterina. species, involved territoriality and, probably, mixed pairings. We showed that allopatric populations of species clearly acoustically differentiated. differences faded out sympatry as result an overall pattern convergence. Unexpectedly, converged for different parameters, namely temporal parameters icterina syntax polyglotta. Hybridization competition could explain convergence Instead, suggest local adaptation to habitat learning might contribute particularly stress cross-species learning, maintaining high levels influence movement zone. (C) 2003 The Linnean Society London. (Less)