Urban ecosystems are intrinsically heterogenous, characterized by dynamic biotic and abiotic interactions that are not witnessed in non-urban environments. Urban flora and fauna experience a suite of novel disturbances and stressors that have led to remarkable phenotypic strategies and adaptations to cope with urban living. Despite recent groundbreaking discoveries and innovation in the fields of urban ecology and evolution, the drivers of urban heterogeneity that induce biological change are seldom articulated.