Species interactions are known to play an important role in community ecology but their influence on phenotypic evolution is not well understood. Where closely related species come into contact they could diverge, converge, or competitively exclude each other. This project will examine the importance of the level of phenotypic and genetic similarity of species in determining patterns of phenotypic variation at contact zones. In particular, the project will focus on variation in traits important in social interactions and how these may diverge or converge between species based on the intensity of resource competition. It will incorporate geographic variation across the landscape and the importance of environmental variation between populations. Bird songs are known to play an important role in territorial interactions, and this study will focus on how the level of ecological and genetic similarity influences the extent of divergence or convergence in songs of Hypocnemis antbirds. Because of the importance of bird song in species recognition, variation in the direction of displacement is of fundamental importance to our understanding of the processes that explain evolutionary diversification. Furthermore, an understanding of how the extent of phenotypic similarity and ecological competition affects the level of range overlap that occurs between species at different contact zones may aid in better understanding current species distributions.