Evolution Following Establishment in a Novel Environment

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The invasion of novel habitats by populations can cause changes within the populations, and these changes can be the basis for the initial stages of speciation. Urban areas represent novel habitats. The Dark-eyed Junco, a passerine bird, recently invaded an urban habitat in San Diego, California. First, urban juncos are compared with juncos in their natural habitat, coniferous-mixed forest, to determine if and how urban juncos have changed in morphology, plumage, behavior, and genetics. Second, because the urban population is isolated, each junco can be uniquely color-banded and monitored throughout the year to determine individual reproductive and survival fates. This enables a thorough study to determine which individuals have higher survival and reproductive rates, which traits are responsible for the differential rates, and how changes in certain traits affect other traits. This research will shed light on the initial stages of speciation, a question central to biology but currently not well understood. The research will also provide knowledge of practical importance - increasing our understanding of how urbanization affects species, and why, how, and at what rate species change as a result of urbanization. There is also an important educational component to this work: each year approximately fifteen undergraduate and graduate students are involved in all aspects of the research.