Nathan Morehouse

Curriculum Vitae

Research Interests: Evolution of sexual dimorphism, visual signaling, optical mechanisms of bright color production, nutrient limitations and life history evolution, stoichiometry of sexually-selected characters.

I am broadly interested in the evolution of morphological differences between the sexes and how these patterns of sexual dimorphism are influenced by the nutritional ecology of species. Nutrient limitations such as nitrogen (N) and phosphorous (P) limitation are thought to be both widespread and profoundly important to the growth and development of individuals, especially herbivores. However, little work has explored the role of such limitations in the development and evolution of sexually-selected traits.

My work currently seeks to understand the role of N-limitation in the development and evolution of a sexually selected trait: sexually-dichromatic, pterin-based wing colors in pierid butterflies. Pierids use pterins, the most N-rich pigments known from the animal kingdom, to produce the vivid yellows, oranges and UV-absorbing whites on the surfaces of their wings. Males of many species invest larger quantities of pterin pigments in to their wings, making their wing colors brighter and more chromatic than those of their female counterparts. However, this increased investment can consume up to 15% of their adult N stores. Pierid butterflies are commonly cited as N-limited herbivores. Therefore, this suggests that the large and irreversible contributions of N to wing coloration (in the form of pterins) may come at some significant cost to males.

I am currently investigating the relationship between dietary N-availability and adult wing coloration within a quantitative genetic framework, which will allow me to evaluate whether inter-individual variation in wing coloration encodes information regarding the phenotype and/or genotypic quality of the bearer. In addition, I am working to assess the signaling role of the resultant pterin-based colors during mating interactions between the sexes.

In addition to this central focus of my research, I continue to be interested and involved in research exploring the fascinating array of optical mechanisms that animals use to produce their bright color patterns. Animals, and butterflies in particular, employ a surprisingly diverse set of optical tricks to generate particular colors and optical effects, many of which remain unexplored or only recently described. For instance, work I performed recently in collaboration with Pete Vukusic at the University of Exeter and Ron Rutowski here at Arizona State shows that pierid butterflies use collections of pterin molecules to simultaneously absorb short wavelength light and reflect long wavelength light, thus producing their highly chromatic colors using a single common morphological element.

Publications

McGraw, KJ, Toomey, MB, Nolan, PM, Morehouse, NI, Massaro, M and Jouventin, P. 2007. A description of unique fluorescent yellow pigments in penguin feathers. Pigment Cell Research. doi:10.1111/j.1600-0749.2007.00386.x

Rutowski, RL, Macedonia, J, Merry, J, Morehouse, NI, Yturralde, K, Taylor-Taft, L, Gaalema, D, Kemp, DJ and Papke, RS. 2007. Iridescent ultraviolet signaling in the Orange Sulphur butterfly (Colias eurytheme): Spatial, temporal and spectral properties. Biological Journal of the Linnean Society 90:349-364.

Morehouse, NI, Vukusic, P and Rutowski, RL. 2007. Pterin pigment granules are responsible for both broadband light scattering and wavelength selective absorption in the wing scales of pierid butterflies. Proceedings of the Royal Society of London B 274:359-366.

Merry, J, Morehouse, NI, Yturralde, K and Rutowski, RL. 2006. Eyes of a patrolling butterfly: Visual field and eye structure in the Orange Sulphur, Colias eurytheme (Lepidoptera, Pieridae). Journal of Insect Physiology 52(3):240-248.

Rutowski, RL, Macedonia, J, Morehouse, NI, and Taylor-Taft, L. 2005. Pterin pigments amplify iridescent ultraviolet signal in males of the orange sulphur butterfly, Colias eurytheme. Proceedings of the Royal Society of London B 272:2329-2335.

 
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