Nate Morehouse, Assistant Professor

I am fascinated by the biology of social interactions and the entangled evolution of traits that compose them. How do eyes influence the evolution of visual signals? How do color preferences shape the appearance of mates and prey communities? How do male ejaculates co-evolve with female reproductive physiology? My research group focuses on these questions using insects and spiders, animals that offer diversity, tractability and inspiration. We seek answers to big-picture questions using techniques drawn from behavioral ecology, vision research, life history theory, nutritional ecology, molecular evolution and comparative phylogenetics. I also have a strong interest in conversations between science and the arts. And I believe in the intrinsic value of human diversity in the scientific enterprise, indiscriminate of age, gender, orientation, race or creed.

2011-present, Assistant Professor, Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA

2009-2011, Marie Curie International Incoming Fellow, Institut de Recherche sur la Biologie de l’Insecte, Université de Tours, France, Postdoctoral Advisor: Jérôme Casas

2002-2009, Ph.D., Biology, School of Life Sciences, Arizona State University, Tempe, AZ, Dissertation Advisor: Ronald Rutowski

1996-2000, B.S., Biological Sciences with a Distinction in Research, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, Thesis Advisor: Cole Gilbert

Curriculum vitae

Current Research

We have a number of research projects underway in the lab. Animals under intensive study at the moment include jumping spiders in the genus Habronattus and butterflies in the family Pieridae.

Our jumping spider research is focused on understanding the visual ecology of these fascinating 8-eyed predators. For example, we recently discovered a novel mechanism that allows spiders in the genus Habronattus to see color. By pairing a red filter with predominantly green-sensitive retinal cells, these animals have increased the color “channels” in their retinas from 2 (UV and green) to 3 (UV, green and red), dramatically expanding the range of colors they can see. We are now asking how this evolutionary innovation may have played a role in the rapid diversification of colorful male displays found across the group. Additional projects are focused on the role of color in foraging and mate choice, and explorations of how these tiny animals cope with the optical challenges imposed by miniaturization of their visual systems.

Using butterflies, we are asking a variety of questions about how sexual selection shapes visual appearance, physiology and individual life histories. In the Cabbage White butterfly, Pieris rapae, we are focused on understanding pre-copulatory mate choice and post-copulatory interactions between male ejaculate compounds and the female reproductive tract. Males transfer up to 13% of their body weight during mating as a protein-rich ejaculate package or spermatophore. Males signal the size of their spermatophore to females with exaggerated color ornaments on their wings. Receipt of these nutrient-rich spermatophores benefits female lifespan and fecundity, but also lengthens the time a female must spend before remating. The resulting sexual conflict over female remating rate has led to an arms race between the sexes over spermatophore digestion. Our research is revealing a number of adaptations that favor male or female control over this process, including male ejaculate proteins that slow spermatophore digestion and potent female proteases and chewing devices that speed up digestion. We are now expanding these studies to ask about the evolutionary mechanisms driving diversification in these sexual traits across the Pieridae.

Lastly, in Colias butterflies, we are exploring the selective forces responsible for the maintenance of a widespread female-limited polymorphism called the ‘alba’ polymorphism. Females in a number of species across the Coliadinae come in one of two types: a species-typical non-‘alba’ form or a paler ‘alba’ form. The persistence of these two morphs poses something of a Darwinian puzzle, as it implies that both morphs retain equal fitness over time. We are studying how limitations to visual discrimination, flexible male mate preferences, and the community of co-flying butterflies may be involved in the evolutionary maintenance of the ‘alba’ phenotype.

Prior Research

My research career started as a little boy that collected everything: feathers, fossils, shells, rocks, stamps, coins. And insects. Lots of insects. My early entomological aspirations were enabled by a tolerant mother and a generous neighbor who gave me my first insect net, a decision she quickly regretted as I proceeded to decapitate the flowers in her beloved garden. It was, after all, the best place to hunt insects in my inner-city neighborhood in Rochester, NY. Later, Bob Cooper at the Rochester Museum and Science Center helped with tricky identifications and gave me a chance to explore the hidden joys of the museum’s collection. My love of insects has stuck with me ever since.

My formal research education began at Cornell University, where I worked with Richard Allen doing insect biodiversity surveys of regrowing rainforest in the Dominican Republic and with Cole Gilbert studying sexual dimorphism in the visual architecture of cleptoparasitic miltogrammine flies. Unlike in most flies, where males have superior vision to aid their pursuit of prospective mates, female miltogrammine flies have larger eyes with more facets. This reversed sexual dimorphism in eye structure supports the unusual lifestyle of these female flies, who follow wasp hosts back to burrows where the flies larviposit young that then parasitize the food provisions of the wasp larvae.

After graduating, I spent two years traveling and working a variety of non-research jobs, including stints as a salmon fisherman in Alaska, farmhand on Vancouver Island, high school science teacher at Wilson Magnet High School, and the general manager and sommelier for the French restaurant 2 Vine.

In 2002, I returned to graduate school at Arizona State University under the mentorship of Ron Rutowski, where I studied sexual selection on male wing coloration in the Cabbage White butterfly, Pieris rapae. Male P. rapae deposit more UV-absorbing pterin pigments in their wing scales, resulting in wings that appear brighter white to us, but more colorful to each other. This sexual dichromatism is the result of female preferences for more colorful males. Females benefit from this color preference by selecting males that have the ability to acquire more protein during development, a limiting nutrient in their larval diet that plays an important role in their adult fitness. More colorful males also transfer larger quantities of ejaculate proteins to their female mates, a source of nutrition that females rely on to build eggs and repair body tissues.

After completing my Ph.D., I joined the lab of Jérôme Casas at the Université de Tours in France as an EU Marie Curie Fellow, where I studied the nutritional dynamics underlying seasonal color polyphenism in the European Map butterfly, Araschnia levana. Spring generations of this butterfly are bright orange, whereas summer adults are black-and-white, a difference in appearance so dramatic that Linnaeus originally described the forms as distinct species. These differences in wing coloration appear to have been the product of interactions between hormonal control of seasonal development and circulating concentrations of pigment precursors in developing pupae. Maintenance of these two forms persists as the result of disruptive selection during development, with intermediate forms exhibiting sharp declines in investment in fitness-related traits such as early life fecundity.

In 2011, I joined the faculty of the Department of Biological Sciences at the University of Pittsburgh.

Publications

BOLD = lab members, **undergraduate authors

2016

Limeri, L.B., and Morehouse, N.I. 2016. The evolutionary history of the ‘alba’ polymorphism in the butterfly sub-family Coliadinae (Lepidoptera: Pieridae). Biological Journal of the Linnean Society, 117(4):716-724. PDF, Supplemental Material

Taylor, L.A., Amin, Z.**, Maier, E.B.**, Byrne, K.J.**, and Morehouse, N.I. 2016. Flexible color-learning in an invertebrate predator: Habronattus jumping spiders can learn to prefer or avoid the color red when foraging. Behavioral Ecology, 27(2):520-529. PDF

2015

Zurek, D.B., Cronin, T.W., Taylor, L.A., Byrne, K.**, Sullivan, M., and Morehouse, N.I. 2015. Spectral filtering enables trichromatic vision in colorful jumping spiders. Current Biology, 25(10), R403-R404. PDF

Plakke, M.S., Deutsch, A.B.**, Meslin, C., Clark, N.L. and Morehouse, N.I. 2015. Dynamic digestive physiology of a female reproductive organ in a polyandrous butterfly. Journal of Experimental Biology, 218, 1548-1555. PDF

Snell-Rood, E., Cothran, R., Espeset, A., Jeyasingh, P., Hobbie, S. and Morehouse, N.I. 2015. Life history evolution in the anthropocene: Effects of increasing nutrients on traits and tradeoffs. Evolutionary Applications. PDF

Meslin, C., Plakke, M.S, Deutsch, A.B.**, Small, B.S.**, Morehouse, N.I., and Clark, N.L. 2015. Digestive organ in the female reproductive tract borrows genes from multiple organ systems to adopt critical functions. Molecular Biology and Evolution, 32(6), 1567-1580. PDFSupplemental Material

2014

Morehouse, N.I. 2014. Condition-dependent ornaments, life histories, and the evolving architecture of resource-use. Integrative and Comparative Biology, 54(4), 591-600. PDF

Limeri, L.B. and Morehouse, N.I. 2014. Sensory biases and the maintenance of color polymorphisms: Viewing the Colias ‘alba’ polymorphism through the male visual system. Functional Ecology, 28(5), 1197-1207. PDF

Ligon, R.A., Dolezal, A.G., Hicks, M.R., Butler, M.W., Morehouse, N.I. and Ganesh, T.G. 2014. Using ants, animal behavior, and the learning cycle to investigate scientific processes. American Biology Teacher, 76, 52-534.  PDF

Taylor, L.A., Maier, E.B.**, Byrne, K.J.**, Amin, Z.** and Morehouse, N.I. 2014. Colour use by tiny predators: Jumping spiders show colour biases during foraging. Animal Behaviour, 90, 149-157. PDF

2013

Hua, J., Morehouse, N.I. and Relyea, R. 2013. Pesticide resistance in amphibians: Induced resistance in susceptible populations, constitutive tolerance in tolerant populations. Evolutionary Applications, 6(7), 1028-1040. PDF

Morehouse, N.I., Mandon, N., Christides, J.P., Body, M., Bimbard, G. and Casas, J. 2013. Seasonal selection and resource dynamics in a seasonally polyphenic butterfly. Journal of Evolutionary Biology, 26, 175-185. PDF

2011

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. PDF

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. PDF

2010

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. PDF

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. PDF

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. PDF

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. PDF

2009

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. PDF

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. PDF

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. PDF

2007

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. PDF

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. PDF

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. PDF

2006

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. PDF

2005

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. PDF