Digest: Morphological diversity in urban dark-eyed juncos

Populations living in cities face challenges from these novel environments that are expected to drive evolutionary adaptation. Do separate populations of a species living in different cities show similar adaptations to the selection pressures imposed by urban environments? Diamant and Yeh (2024) address this question by comparing the morphological characteristics of dark-eyed juncos in 3 California cities to non-urban junco morphologies. They find that wing size is consistently smaller in more urbanized environments regardless of the population, but bill size tends to vary between urban populations.