DISSERTATION RESEARCH: Adaptive Radiation and Interspecific Gene Flow in High Andean Espeletiinae: A Coalescent Approach

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9623696 Schaal Research funded by this award probes the workings of adaptive radiation, one of the fundamental evolutionary processes that foster biodiversity. Adaptive radiation is manifest in groups of species which, from their origins in a single common ancestor, have experienced exceptional and often rapid diversification. In plants, this phenomenon is most apparent within high elevation tropical habitats. In the Andes mountains of northern South America, the subtribe Espeletiinae (Asteraceae) has diversified into over 80 species and a spectacular array of morphological forms, making it a classic example of adaptive radiation and an important model system for studying evolution in plants. One of the many interesting characteristics of this group is the high frequency with which several highly inter-fertile species of Espeletiinae co-occur within the same habitats. This raises the main questions addressed in this award: how often do such species hybridize, and what role has hybridization played in the adaptive radiation of this group? The potential for hybridization to spread adaptive genes from one species to another and even result in the instant creation of new species makes these questions particularly fascinating. With support from this award, genetic samples will be collected from many individuals of these co-occurring species. Variation among these individuals and species, detected by DNA sequencing, will be analyzed using the statistically powerful framework provided by recent theoretical advances in coalescent theory, making it possible to test for evidence of genetic exchange among species. Results will provide answers to basic questions about the role of hydridization, not just in the adaptive radiation of the Espeletiinae but it all plants where hydridization may play an important role in evolution. Findings will enhance our knowledge of tropical biodiversity and aid in conservation strategies for endemic plant species.