Urban versus forest ecotypes are not explained by divergent reproductive selection

Increasing urbanisation offers a unique opportunity to study adaptive responses to rapid environmental change. Numerous studies have demonstrated phenotypic divergence between urban and rural organisms. However, comparing the direction and magnitude of natural selection between these environments has rarely been attempted. Using seven years of nest-box breeding monitoring of great tits (Parus major) in the city of Montpellier and in a nearby oak forest, we find phenotypic divergence in four morphological and two life-history traits between urban and forest birds. We then measure reproductive selection on these traits, and compare selection between the habitats. Urban birds had significantly smaller morphological features than their rural counterparts, with shorter tarsus, lower body mass and smaller wing and tail lengths relative to their overall body size. While urban female tarsus length was under stabilising selection, and forest males show positive selection for tarsus length and ne...