Hotspots of Genome Evolution in a Rapid Vertebrate Radiation

Evolutionary radiations are groups of organisms that produce new species at an exceptionally high rate. Biologists have long used such radiations as model systems to study the process of speciation. Past studies have commonly focused on the traits of organisms or their habitats that might have facilitated the formation of new species. With the development of genome sequencing methods, however, it is now possible to identify specific genes that might be involved in producing evolutionary radiations. This project aims to identify genes that may be associated with the exceptional diversification of a group of small, colorful songbirds in North, Central, and South America. The project offers a rich opportunity to understand the genetic bases of evolutionary radiations and the substrate that has given rise to one of the most diverse vertebrate species groups. The project will include training and mentorship of undergraduate and graduate students, as well as outreach programs to extend the research to the broader community.

The research project focuses on wood warblers (Parulidae), a family of birds with over 100 species that diversified within the last 10 million years, and which has one of the fastest evolutionary rates across songbirds. The goal of the project is to study the evolutionary history of genes potentially involved in the diversification of this group. An important starting point requires some knowledge of potential candidate genes involved, something lacking in nearly all non-model biological systems. In warblers, however, previous studies of independent hybrid zones have generated a set of candidate genomic regions associated with species differences, many of which have been found to be involved in plumage pigmentation. The project draws upon the tools and theoretical framework of phylogenetic comparative methods and will analyze whole genome sequence data from multiple individuals of every species in the radiation. The work will first quantify patterns of genomic divergence among closely related species to identify chromosomal regions and genes associated with exceptional lineage-specific evolution. Second, the researchers will estimate genealogical discordance in the topologies of trees sampled across the genomes of species in the radiation to test for evidence of reticulate evolution. Finally, by making use of the widespread availability of genomes across the avian tree of life, the project will extend beyond warblers to address a fundamental question regarding the extraordinary speciation within evolutionary radiations: are there genomic predictors of diversification?

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.