Dissertation Research: Investigating genomic signatures of speciation in tropical montane kingfishers (Aves: Halcyonidae)

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This study will use genomic data to investigate the evolutionary mechanisms that led to the divergence of two Mountain Kingfisher species from a single common ancestor. Both of these two closely related bird species live in the highlands of Papua New Guinea; one species occurs at lower elevations, the other occurs at higher elevations. Scientists have long known that tropical mountain ranges, like these in Papua New Guinea, have many more species of plants and animals than expected based on their small total area. However, a fundamental unanswered question is whether random or adaptive evolutionary processes are more important in generating this increased biological diversity. This study will use mathematical models and DNA sequence data collected from field and museum specimens to test alternate explanations for the evolutionary divergence of these two species. Identifying the processes responsible for the evolution of new species is important for understanding the history of life on Earth and for predicting how environmental complexity and change leads to new biological diversity. Results of this work are expected to provide important insights for conservation management of montane bird species. In addition, the project includes creation of public museum displays and other educational outreach activities. Sister species with differing elevational ranges present a powerful system for understanding the interplay between evolutionary processes and geographic and environmental complexity. This project will explore patterns and drivers of whole genomic differentiation in Syma genus forest kingfishers (Aves: Halcyonidae), a young species pair with parapatric lowland and highland distributions in Papua New Guinea. The researchers will generate single nucleotide polymorphism data and whole genome DNA sequences from samples collected in the field and from natural history museum collections. Using these data they will describe phylogeographic patterns and infer demographic history in both species, estimate phylogenetic relationships and conduct species delimitation, and assess the relative contribution of neutral and adaptive evolutionary processes. In combination, these analyses will provide a test of a hypothesis of ecological speciation in Syma due to disruptive natural selection across an elevational gradient. The research will additionally reveal important clues regarding the evolutionary mechanisms responsible for disproportionate species richness in tropical montane systems.