Research

Feather microstructures 

I'm interested in the evolution, development, and optical effects of modifications in feather branches (barbs and barbules, also known as feather microstructures) in pigmented and structurally colored feathers. How do evolutionary changes in barbs and barbules alter feather color, and are microstructural modifications that enhance coloration constrained by selection for other feather functions? Using a combination of confocal and electron microscopy, spectrophotometry, and developmental approaches, I'm studying these questions in tanagers and other birds.

Optics and evolution of achromatic feather layers

A striking feature of colorful plumage is that color is confined to feather tips; feathers are arranged on the body so that the exposed tips create a continuous patch of color and the achromatic (black, white, and/or gray) bases are concealed. The overall effect is that colorful plumage contains multiple layers, including both exposed colorful layers and achromatic layers that are almost entirely concealed beneath colorful layers. I'm using hyperspectral and multispectral imaging, microspectrophotometry, confocal and electron microscopy, and modeling to investigate the optics and evolution of achromatic feather layers in tanagers and other birds.

Cover image of pigmented eggs from Journal of Heredity. Image by David Ocampo.

Avian color genetics and color vision

A wide range of genetic and developmental mechanisms underlie the diversity of colors and patterns that make avian feathers, skin, eyes and eggs so stunning. I synthesized recent advances in avian color genetics and their evolutionary implications in a review paper, with an emphasis on emerging areas of research - structural coloration, colors produced by interacting pigments and nanostructures, and genetic links between the visual system and coloration.

Tanager phylogenetics and macroevolution

Macroevolutionary approaches to understanding trait evolution rely on phylogenies. As part of my Masters work with Kevin Burns, I used ultraconserved elements (UCEs) sequenced from museum tissues to infer phylogenies of tanagers (Aves: Thraupidae), the largest family of songbirds. I used these phylogenies and previously published datasets of tanager traits (plumage, song, niche, morphology) to investigate macroevolutionary correlates of speciation rates in tanagers, with a particular focus on traits under social and sexual selection (plumage, song) relative to traits under natural selection (niche, morphology).

Past projects and other interests

Microbiomes

Through coursework at San Diego State University and Princeton University, I've worked on microbiomes in sharks and hyraxes.

Bat wing evolution

As an undergraduate researcher and research assistant in the Swartz Lab, I studied the evolution and function of bat wing muscles and joints.

Conservation 

I spent three field seasons as a Biological Sciences Technician for the Sierra Nevada Carnivore Monitoring Program before beginning my Masters.

Mass extinctions

As an undergraduate researcher in the Whiteside Lab, I studied the ocean geochemistry of the end-Triassic mass extinction.

Publications


Price-Waldman, R.M., and M.C. Stoddard. (2021) Avian coloration genetics: Recent advances and emerging questions. Journal of Heredity. https://doi.org/10.1093/jhered/esab015


Fialko, K., J. Ali, L. Céspedes Arias, J. Drucker, K. Nordén, T. Price, R. Price-Waldman, S. Pruett-Jones. (2021) Book review: The Sensory Ecology of Birds. Ornithology ukab001.


Price-Waldman, R.M., A.J. Shultz, K.J. Burns. (2020) Speciation rates are correlated with changes in plumage color complexity in the largest family of songbirds. Evolution 74 (6): 1155-1169 https://doi.org/10.1111/evo.13982


Doane, M.P., [...multiple authors], R.M. Price-Waldman, R.A. Edwards, E.A. Dinsdale. (2020) The major evolutionary split between elasmobranchs and teleost fishes extends to the diversity partitioning of the skin microbiomes. Microbiome 8 (93) https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-020-00840-x


Bahlman, J.W., R.M. Price-Waldman, H.W. Lippe, K.S. Breuer, S.M. Swartz. (2016) Simplifying a wing: diversity and functional consequences of digital joint reduction in bat wings. Journal of Anatomy 229 (1): 114-27 https://doi.org/10.1111/joa.12457


Kasprak, A.H., J. Sepulveda, R.M. Price-Waldman, K.H. Williford, S. Schoepfer, J.W. Haggart, P.D. Ward, R.E. Summons, J.E. Whiteside. (2015) Episodic photic zone euxinia in the northeastern Panthalassic Ocean during the end-Triassic extinction. Geology 43: 307-310 https://doi.org/10.1130/G36371.1


Collaborators