UCLA

Urbanization is rapidly changing landscapes worldwide, driving phenotypic divergence in numerous urban wildlife populations. However, the strength and direction of this divergence may vary across and within cities. Here, we investigated the influence of fine-scale environmental variation on the morphological divergence of dark-eyed juncos (Junco hyemalis) across three Southern California cities. We explored how bill shape varies across three urban populations and one non-urban population, and we tested whether bill shape varies with fine-scale changes in resource availability across urban Los Angeles. Bill shape differed between urban and non-urban populations, but we did not observe expected patterns of bill shape divergence across cities. Bill shape variation also was not associated with fine-scale variation in resource availability within urban Los Angeles. Our findings suggest urban junco bill shape may be driven by non-adaptive processes, other environmental factors, or a more complex suite of urban selection pressures.