Rosamari Orduna | UCLA Ecology & Evolutionary Biology

Research Interests

I am a third-year PhD student in the Department of Ecology and Evolutionary Biology at UCLA, where I study the mechanistic and evolutionary basis of color diversity in coral reef fishes. My research combines imaging spectrophotometry and microscopy to investigate how different arrangements of pigment cells and structural elements — such as iridophores containing guanine crystals — generate the extraordinary range of colors observed across reef fish species. A particular focus of my work is blue coloration, which arises predominantly through structural mechanisms in most reef fish families, with true blue pigment (via cyanophores) known only from a small number of dragonets.

A central theme of my research is convergent evolution: why do similar color patches appear repeatedly across unrelated reef fish families such as labrids, surgeonfishes, damselfishes, and mandarinfishes? By measuring reflectance spectra of fresh specimens using an imaging hyperspectrophotometer and comparing the microstructural basis of coloration through skin cross-sections, I aim to establish a comprehensive framework linking spectral signatures to color-producing mechanisms. This work contributes to our broader understanding of how color evolves in vertebrates and the functional significance of convergent coloration across the tree of life.

Curriculum Vitae Email UCLA EEB

Fish Color & Reflectance

Examples from ongoing research on color diversity and spectral reflectance in coral reef fishes.

Diversity of colorful coral reef fish species — **Coral Reef Fish Color Diversity** Reef fishes display some of the most striking color patterns among all vertebrates, with vivid hues produced through pigmentary and structural mechanisms.

Blue coral reef fish study system with labeled species — **Study System: Blue Reef Fishes** A selection of species examined in this research, spanning labrids, damselfishes, surgeonfishes, and mandarinfishes — families with widespread convergent blue coloration.

Reflectance spectrum graph of Chrysiptera taupou blue damselfish — **Hyperspectral Reflectance Measurement** Mean reflectance spectrum of the blue patch in *Chrysiptera taupou* (Fiji blue devil damselfish), measured using an imaging hyperspectrophotometer. Peak reflectance at 457.7 nm confirms structural blue coloration.

Digital microscope image of parrotfish skin showing pigmented and structural color cells — **Skin Microstructure** Digital microscope image of a parrotfish blue skin patch, showing the arrangement of melanophores (red arrows) and iridophores (blue arrows) that together produce structural coloration via diffuse scattering of short-wavelength light.