The formation of new species (speciation) is generally thought to begin with geographic isolation of populations. When different populations of a single species are isolated by geographic barriers, they are likely to evolve differences. If the differences accrued in isolation are substantial, these populations will be considered different species. However, the processes that control the initial stage of speciation, the differentiation of geographically isolated populations, are poorly understood. This proposal investigates the factors that control differentiation of populations in geographic isolation. In particular, it examines the roles that time spent in geographic isolation, and the degree of geographic isolation experienced through time, play in determining levels of population differentiation. This proposal uses bird species found in the cloud forest of the Andes as a model system for hypothesis testing, as many populations in this region show variable levels of differentiation across geographic barriers. Recently developed genetic techniques will be used to infer levels of genetic differentiation, and museum specimens of Andean birds will enable measurement of differentiation in plumage and morphology among populations.
Understanding the causes of different amounts of divergence from geographically isolated species will help illuminate the processes involved in the initial phase of speciation for a large portion of earth?s biodiversity. This project includes training of Peruvian scientists and mentorship of local Chicago area high school students and undergraduates in laboratory methods. This project also will involve public educational outreach on genetic and evolutionary research at the DNA Discovery Center at the Field Museum in Chicago.
