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Tropical Ecology has been the focal point of Thomas Walla, PhD, interests since his first trip to Ecuador in 1991. Since that time he has sought to bring the wonders of tropical diversity to the classroom and his research program. Walla's current research is focused on measuring the diversity of interactions along the elevation gradient that spans the eastern Andes to the flood plain forests of the Amazon. He works with a diverse group of collaborators collecting and rearing the caterpillars of butterflies and moths, the host plants they feed on and the natural enemies that attack them. Here at Colorado Mesa University, Walla teaches a diversity of courses including Insect Biology, Plant-Animal Interactions, Tropical Ecology, Advanced Ecological Methods, Fundamentals of Ecology and Evolution and General Human Biology.

Walla believes teaching is the most profound contribution a person can make to a community. Through his interactions with students he seeks to enhance their life experiences and appreciation for the life that surrounds them. Close examination of a caterpillar brings not only a quiet pleasure, but an opportunity for a deeper understanding of processes on earth. Caterpillars, nearly blind, soft bodied organisms are important herbivores that consume the leaves of plants rich in biologically active toxic compounds that might kill another organism. Their bodies are armed with defenses that include toxin filled sharp hairs, spines, chemical glands and chemicals that protect them from their enemies. Despite these formidable safeguards, parasitoid wasps and flies consistently find their way in to deposit their larvae in the fat nutritious bodies of caterpillars. There they will feed for weeks or even months, slowly ingesting the organs of the caterpillar for their own nourishment until they finally grow large enough that they rip out of the body cavity and pupate; their final step in becoming an adult parasitoid. Thus caterpillars, feasting on plants and a feast themselves for parasitoids are sandwiched between the two great trophic forces, one from the bottom up, the other from the top down, that drive the evolution of diversity in form and function of life on earth. So perhaps a caterpillar, despite its diminutive size and humble ways, can teach us something of life.

In his research Walla understands the patterns of trophic interactions in the tropics and the natural history of individual species as it contributes to the greater ecological patterns. His work in the tropics would not be possible were it not for the strength and dedication of the collaborative team he has worked with, and the remarkable skill and hard work performed by Wilmer Simbana and Luis Salagado. This research team has made many significant contributions to the understanding of tropical systems. These include the development of a beautifully simple model for measuring and exploring the diversity of species interactions in systems where the interactions are exceptionally numerous and incompletely sampled. Additionally, this research team has shown that the tendency for herbivores to specialize on small numbers of host plants increases with proximity to the equator. This pattern supports a branch of evolutionary theory that predicts tropical systems evolve faster and with greater co-evolutionary interactions compared to temperate zone systems, a hypothesis that has been poorly supported due to a lack of data for nearly half a century.

Travel to the tropics is a transformative experience. To bring this level of experiential learning to the students of Colorado Mesa University, I have led more than 10 Tropical Field Biology courses to Ecuador where students have had the opportunity to live and work in the field alongside professional biologists to expand their understanding of their own potential in biology. These field courses are perhaps the most meaningful teaching experiences of my career and they succeed because the students who are ready to the enter the Amazon are ready see change in their lives.

Curriculum Vitae

Selected Publications

Walla, TR., and Greeney, HF. 2012 Under cover of darkness, caterpillars take flight: The immature stages and feeding ecology of the Glasswinged Butterfly, Oleria baezana (Ithomiinae) in Eastern Ecuador. Journal of Insect Science. 12: 106.

Dyer, L.A., Walla, T.R., Greeney, H.F., Stireman III, J.O., Hazen, R.F. 2010. Diversity of interactions: a metric for studies of biodiversity. Biotropica. 42: 281-289.

Jarle Tufto, Russell Lande, Thor-Harald Ringsby, Steinar Engen, Bernt-Erik Sæether, Thomas R. Walla and Philip J. DeVries 2012. Estimating Brownian motion dispersal rate, longevity and population density from spatially explicit mark-recapture data on tropical butterflies. Journal of Animal Ecology vol 81 Issue 4 pgs 756-769.

Rodriguez-Casteneda, Genoveva; Dyer, Lee; Brehm, Gunnar; Connahs, Heidi; Forkner, Rebecca; Walla, T DeVries, P.J. & T.R. Walla. 2001. Long-term spatial and temporal species diversity in a neotropical fruit-feeding nymphalid butterfly community. Biol. J. Lin. Soc. 74: p.1-15

Greeney, HF, M Lysinger, TR Walla, & J Clark 1998. First description of the nest and egg of the Tanager Finch (Orreothraupis arremenops) with additional notes on behavior. Ornitologia Neotropical 9: 205-207
Matthew L. Forister, Vojtech Novotny, Anna K. Panorska, Leontine Baje, Yves Basset, Philip T. Butterill, Lukas Cizek, Phyllis D. Coley, Francesca Dem, Ivone R. Diniz, Pavel Drozd, Mark Fox, Andrea E. Glassmire, Rebecca Hazen, Jan Hrcek, Joshua P. Jahner, Ondrej Kaman, Tomasz J. Kozubowski, Thomas A. Kursar, Owen T. Lewis, John Lill, Robert J. Marquis, Scott E. Miller, Helena C. Morais, Masashi Murakami, Herbert Nickel, Nicholas A. Pardikes, Robert E. Ricklefs, Michael S. Singer, Angela M. Smilanich, John O. Stireman, Santiago Villamarín-Cortez, Stepan Vodka, Martin Volf, David L. Wagner,

Thomas Walla, George D. Weiblen, Lee A. Dyer. The global distribution of diet breadth in insect herbivores. Proceedings of the National Academy of Sciences, 2015; 112 (2): 442 DOI: 10.1073/pnas.1423042112