Figure 1. Completing the puzzle. Just as the picture on a puzzle cannot be fully understood from a single piece, no single method can tell us all we need to learn about adaptation in any environment, including urban environments, and each piece can tell us something uniquely important. When pieced together, we obtain a more comprehensive picture of adaptation. Employing complementary approaches that account for both taxonomic and environmental variation provide different pieces of evidence to better understand evolutionary processes and patterns in general and may help move adaptation research in urban ecosystems forward productively.