My research integrates ecological and evolutionary concepts with the ultimate goal to understand how complex traits evolve. The two central goals of my research are to understand how behavior evolves and how evolutionary changes in behavior influence population dynamics that ultimately shape macroevolutionary processes. To achieve these goals, I use large- scale field experiments, empirical measures of lifetime fitness, field endocrinology and molecular multi-generational pedigree reconstruction to investigate the dynamics of trait evolution in the context of range expansion and species coexistence in passerine birds. Current projects in my lab include 1) eco-evolutionary feedbacks between behavioral change and population density, 2) investigating proximate epigenetic basis of maternal effects on dispersal strategies 3) investigating neuroendocrine mechanisms and developmental constraints on personality traits 4) comparative studies across vertebrates on evolution of traits that affect range limits and species coexistence.