Hybridization occurs when two different species interbreed and produce offspring. While we often think of hybridization in animals as something that’s rare, or something that is a reproductive dead end, it is actually fairly common, especially in birds, and it is an important tool to help us understand how and why species evolved in the first place. In the bird world, it’s estimated that hybridization occurs in at least 10% of all species.
Hybrid zones, geographic regions where two species overlap and interbreed, have been particular important in shaping our understanding of evolution. In the Great Plains of North America, multiple pairs of bird species hybridize, including the Eastern and Spotted Towhees, Indigo and Lazuli Buntings, and the Baltimore and Bullock’s Orioles.
The orioles in particular have a long and fascinating history of research dating back to the 1950s, and through this long history of research, we have been able to understand how patterns of hybridization have changed over time. Using an integrative approach that combines morphology, genomics, and climate change research, we have explored the oriole hybrid zone to understand how and why these species hybridize, and what it can tell us about biodiversity and the evolution of species.
Shawn Billerman works at the Cornell Lab of Ornithology, where he is a science editor with Birds of the World, an online resource and the world’s largest, most comprehensive, scholarly resource for birds that is filled with more than 11,000 species accounts and 250 family accounts. With Birds of the World, he works with authors and contributors from around the world so they can share their passion about the species that they study and update species accounts. He also works with the Clements Checklist team to help maintain taxonomy, where he has a special interest in bird families.
In addition to his work with Birds of the World, he is also broadly interested in understanding patterns of avian speciation. His past research for his PhD and postdoctoral fellowship, which focused on hybridization between the Red-naped and Red-breasted Sapsuckers as well as birds of the Great Plains, including the Baltimore and Bullock’s Orioles, has taken advantage of museum collections and focused on using hybrid zones to understand how intrinsic and extrinsic processes have influenced how and where species hybridize, and ultimately what factors are important to understanding reproductive isolation.
