Nathan Morehouse

Assistant Professor

Evolution of coloration

Nathan Morehouse
Office: (412) 624-3378
Lab: (412) 624-3351
223 Clapp Hall
4249 Fifth Avenue
Pittsburgh, PA 15260
Education

Dr. Morehouse received his Ph.D. in 2009 with Ron Rutowski at Arizona State University, performed his postdoctoral studies with Jérôme Casas at the Université de Tours, France, and joined the Department in 2011

Biography

Dr. Morehouse received his Ph.D. in 2009 with Ron Rutowski at Arizona State University, performed his postdoctoral studies with Jérôme Casas at the Université de Tours, France, and joined the Department in 2011

Figure 1. Iridescent scales on the wing of a tropical butterfly (above), with an electron micrograph of the photonic structures that produce the color (below, imaged from an area the size of the white square above).Figure 1. Iridescent scales on the wing of a tropical butterfly (above), with an electron micrograph of the photonic structures that produce the color (below, imaged from an area the size of the white square above).As conspicuous members of every biological community, brightly colored animals have fascinated and puzzled us since time immemorial. They have also taught us much about the process of evolution, from Darwin’s early musings about sexual selection to contemporary work on hybrid speciation in mimetic butterflies. In the Morehouse lab, we seek fundamental insights into the evolution of bright coloration, focusing on how animals produce their colors, what they communicate with them, and how their visual systems perceive and process colorful signals. Our research draws from a broad range of techniques, integrating biophotonics, pigment biochemistry, animal behavior, visual ecology, developmental physiology, nutritional ecology and evolutionary genetics.

Color Production

Animals use a bewildering array of mechanisms to produce color in their tissues, from pigments synthesized de novo to complex crystalline structures that selectively reflect certain wavelengths of light. Even in well studied animal groups, such as birds and fish, much remains unknown regarding how color is produced. We study the optical properties and basic constituents of colored animal tissues using electron and light microscopy, UV-vis microspectrophotometry, optical measurements, physical modeling, and biochemical techniques for pigment identification (see Fig. 1). Insects, spiders and birds are some of our favorite subjects, but we’re always open to looking at other systems.

Figure 2.  A Pieris rapae bilateral gynandromorph, with typical female coloration on the left and male coloration on the right, as viewed by humans (above), and as viewed by these butterflies and their avian predators (below)Figure 2. A Pieris rapae bilateral gynandromorph, with typical female coloration on the left and male coloration on the right, as viewed by humans (above), and as viewed by these butterflies and their avian predators (below)Color Communication

Color signals are a key component of the umwelt of most higher animals. In fact, many animals have color vision that exceeds our own, with fine color discrimination extending into the UV and deep red. Our research seeks to enter this richer world of color to understand how and why animals use visual signals to communicate. We do this using behavioral assays, manipulations of visual signals, measurements of color patterns, light environments and visual system components, and mathematical modeling of the visual responses of focal species. We are interested in uncovering not only how specific animals communicate with color, but also broader themes in the co-evolution of visual signals and visual systems.

Color Evolution

Color signals present unique opportunities to test fundamental evolutionary theory, from how ornaments exaggerate under directional female choice to resolutions of intralocus sexual conflict. Because they often require large quantities of limiting nutritional resources, color signals also compete with other key life history traits during development, making them important players in the evolution of life history strategies. Our research leverages techniques from nutritional ecology, developmental biology, experimental evolution and quantitative genetics to probe the evolutionary dynamics of color traits.

Feel free to email or call if you would like to know more about our research or how you can get involved.

Recent Publications
  • Meadows, M.G., Morehouse, N.I., Rutowski, R.L, Douglas, J.M. and McGraw, K.J. 2011. Quantifying iridescent coloration in animals: A method for improving repeatability. Behavioral Ecology and Sociobiology. 65(6), 1317-1327. doi: 10.1007/s00265-010-1135-5

  • Van Gossum, H., Bots, J, Van Heusden, J, Hammers, M., Katleen, H. and Morehouse, N.I. 2011. Reflectance spectra and morph mating frequencies support intraspecific mimicry in the female colour polymorphic damselfly Ischnura elegans. Evolutionary Ecology. 25(1), 139-154. doi: 10.1007/s10682-010-9388-z

  • Morehouse, N.I. and Rutowski, R.L. 2010. In the eyes of the beholders: Female choice and avian predation risk associated with an exaggerated male butterfly color. American Naturalist, 176(6), 768-784. doi:10.1086/657043

  • Morehouse, N.I., Nakazawa, T., Booher, C.M., Jeyasingh, P.D. and Hall, M.D. 2010. Sex in a material world: Why the study of sexual reproduction and sex-specific traits should become more nutritionally-explicit. Oikos, 119(5), 766-778. doi:10.1111/j.1600-0706.2009.18569.x

  • Morehouse, N.I. and Rutowski, R.L. 2010. Developmental responses to variable diet composition in the cabbage white butterfly, Pieris rapae: the role of nitrogen, carbohydrates and genotype. Oikos, 119(4), 636-645. doi:10.1111/j.1600-0706.2009.17866.x

  • Lindstedt, C., Morehouse, N.I., Pakkanen, H., Casas, J., Christides, J.P., Kemppainen, K., Lindström, L. and Mappes, J. 2010. Characterizing the pigment composition of a variable warning signal of Parasemia plantaginis larvae. Functional Ecology, 24(4): 759-766. doi: 10.1111/j.1365-2435.2010.01686.x

  • Morehouse, N.I. and Rutowski, R.L. 2009. Comment on “Floral iridescence, produced by diffraction optics, acts as a cue for animal pollinators.” Science, 325, 1072-d. doi:10.1126/science.1173324

  • Meadows, M.G., Butler, M.W., Morehouse, N.I., Taylor, L.A., Toomey, M.B., McGraw, K.J. and Rutowski, R.L. 2009. Iridescence: views from many angles. Journal of the Royal Society Interface, 6, S107-113. doi:10.1098/rsif.2009.0013.focus

  • Shawkey, M.D., Morehouse, N.I. and Vukusic, P. 2009. A protean palette: colour materials and mixing in birds and butterflies. Journal of the Royal Society Interface, 6, S221-S231. doi:10.1098/rsif.2008.0459.focus

  • Morehouse, N.I., Vukusic, P. and Rutowski, R.L. 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. doi:10.1098/rspb.2006.3730

  • McGraw, K.J., Toomey, M.B., Nolan, P.M., Morehouse, N.I., Massaro, M. and Jouventin, P. 2007. A description of unique fluorescent yellow pigments in penguin feathers. Pigment Cell Research, 20, 301-304. doi:10.1111/j.1600-0749.2007.00386.x

  • Rutowski, R.L., Macedonia, J., Merry, J., Morehouse, N.I., Yturralde, K., Taylor-Taft, L., Gaalema, D., Kemp, D.J. and Papke, R.S., 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. doi:10.1111/j.1095-8312.2007.00749.x

  • Merry, J., Morehouse, N.I., Yturralde, K., and Rutowski, R.L., 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. doi:10.1016/j.jinsphys.2005.11.002

  • Rutowski, R.L., Macedonia, J., Morehouse, N.I. 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. doi:10.1098/rspb.2005.3216