Feathers are the most complex epidermal appendages found on vertebrates. Using single cell and single nuclear RNA sequencing, I've created a cell type atlas of developing chicken feathers. I've used these data to better understand cell type developmental trajectories, cell-cell signaling within the feather, and I've begun to explore feather evolution by creating the first feather cell type tree. You can read more about this work here: https://doi.org/10.1111/ede.70016 (or download it for free here)

Feather color is often through as being controlled through production (or inhibition of production) of melanin. Little work has explored the developmental mechanisms behind feather patterning and the individualized role of the melanocytes or the keratinocytes. By drawing on my cell type atlas work, I'm exploring the development of color at a cell type level. We're starting to understand the cell type specific changes involved in making a feather colorful.

Working on feathers has given me a special appreciation for the weirdest feathers. At the extreme ends of feather morphology, it can often be difficult to tell feathers from non-feathers. In this project, I'm exploring some of these stranger morphologies to describe the extent of epidermal diversity in extant birds. This work will enable paleontologists to better distinguish between feathers, and weird bird skin.

Tyrrell et al 2019 described a new cellular structure in the retina of two species of new world flycatchers. As someone interested in novel cell types in birds, this work was particularly exciting since the evolution of new photoreceptor cell types is quite rare in vertebrates. We've begun working on describing this cell type from single cell sequencing data and hope to uncover the evolutionary origins of this cell type.