Postdoctoral Fellowship: PRFB: Genetic and Mechanistic Bases of Rapid Phenotypic Evolution: Functional Implications & Environmental Associations of Structural White Color in Birds

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2025. The fellowship supports research and training of the fellow that will contribute to biology in innovative ways. To better understand Earth's biodiversity, we need to know how complex traits evolve quickly.

This project focuses on one such trait-structural white feathers in birds-to learn how it forms, how often it has evolved, and how it affects a feather's function. Feather colors come from pigments that absorb light or from microscopic structures that reflect it. White feathers form when they lack pigment and their microscopic structures are unorganized.

This causes them to reflect all visible light, making them look white. After 200-years of research, scientists discovered a special type of white created by organized microscopic structures. Although considered rare, new research suggests it may be more common and could help explain how feather colors evolve quickly.

This project will use feather structure analysis, genetic techniques, and ecological data to find out how and why this unique color evolved in three groups of birds known for fast color changes-tanagers, jays, and kingfishers. The project also supports public outreach at the Natural History Museum of Los Angeles County and helps students through mentoring and workshops.

Research into the mechanisms behind rapid phenotypic evolution will provide insights into the proximal (mechanistic) and ultimate (phylogenetic history and natural selection) factors that drive predictable patterns of phenotypic change, a central Rule of Life. Avian plumage is a complex phenotype that has provided many insights into the tempo and mode of phenotypic evolution.

Previous research has typically focused on easily discernible colors in the human visible spectrum, such as color produced by pigments (brown, red, yellow) or iridescence produced by nanostructures within feathers (structural color). Structural white color, specifically produced by ordered nanostructures within feather barbs, is harder to distinguish in the human visible system and is considered extremely rare in birds.

Preliminary investigations by the fellow show that this phenotype may be more common and could be a mechanism for producing novel plumage colors. The project will (1) characterize how structural white is produced and whether it has convergently evolved across three ecologically distant clades, (2) investigate phenotype-environment associations and functional trade-offs of structural white color, and (3) explore lineage-specific molecular adaptations to produce structural white feathers and test for convergent evolution at the genetic level that produce it.

Ultimately, this research will shed light on how novel traits emerge and shape species interactions with their environment.

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.