Biological Science Faculty Member - Retired

Robert O. Lawton Distinguished Professor
B.A., University of Pennsylvania, 1975Ph.D., Duke University, 1980

Research and Professional Interests:

My research has revolved around understanding how ecological processes drive evolutionary ones and, sometimes, vice-versa.  In a more down-to-earth vein, my research is focused on how and why features of animals vary from one population to another and whether those differences contribute to creating differences among the ecosystems in which those populations are embedded. 

For example, populations of Trinidadian guppies at higher elevations in the Northern Range mountains have diverged markedly from those at lower elevations.  The higher population density and lower level of food per individual at higher elevations, which are the result of reduced predation levels on those guppies, cause natural selection to favor different features in the higher elevation populations than those in the lower elevation populations.  At the higher elevations, selection favors guppies that mature later and larger than those at low elevations, forage less selectively, and consume more algae than guppies at lower elevations that experience higher predation pressure.  This is an example of how ecological differences generate evolutionary ones.  However, the upstream guppies’ plant-based diet, combined with their higher population densities and larger body sizes, affects the stream ecosystem in a fundamentally different manner than we see at the lower elevations.  This is an example of how an evolutionary process can alter an ecological one.

One of the challenges in this type of research is elucidating which ecological factors are driving the divergence in particular traits.  In the guppies, this meant performing experiments that could distinguish whether the release from predation or the higher population densities were responsible for the distinctive life histories of higher-elevation guppies.  I have also confronted this challenge in my research on populations of the least killifish in north Florida.  Populations in spring-fed rivers exhibit consistent differences in many traits from populations in lakes.  However, the lakes and rivers differ in their thermal regimes, microbial flora, water chemistry, and the ensemble of predators that attack these tiny animals.  Over many years, my colleagues, students and I have learned that all of these factors play a role but they do so in different, sometimes counter-intuitive ways. 

The expertise I’ve acquired from my research has allowed me to contribute to several problems in conservation.  From 2000 to 2005, I chaired a panel of scientists charged by the National Marine Fisheries Service with reviewing plans for recovering species of threatened and endangered Pacific salmon.  From 2016-2020, I chaired two committees for the National Academies of Science, Engineering, and Medicine on the evolutionary relationships among red wolves, coyotes, and other wolves, with an eye toward assessing the validity of retaining species recognition for red wolves. 

With one foot in ecology and another in evolutionary biology, I have guided students in a diversity of research projects. My graduate and postdoctoral students have studied topics from the community ecology of Amazonian frogs to the population genetics of gag grouper, from the development of personalities in bluefin killifish to the prenatal conflict between mothers and offspring in the least killifish.  The common element in these projects is an immense curiosity about nature and the determination to find answers to important conceptual questions about nature, regardless of how challenging the path to those answers might be.

Selected Publications:

Selected Publications (2023-2026)

Travis, J.  2023.  Phenotypic Plasticity.  In David Gibson, ed., Oxford Bibliography of Ecology. 

            Oxford University Press, New York. doi: 10.1093/OBO/9780199830060-0242.

Travis, J., R. D. Bassar, T. Coulson, A. Lopez-Sepulcre, and D. Reznick.  2023.  Population

            regulation and density-dependent demography in the Trinidadian guppy.  American

            Naturalist 202:413-432.

Potter, T., J. Arendt, R. D. Bassar, B. Watson, P. Bentzen, J. Travis, and D. Reznick.  2023. 

            Female preference for rare males is maintained by indirect selection in Trinidadian

            guppies.  Science 380:309-312.

Travis, J., R. Bassar, T. Coulson, D. Reznick, and M. Walsh.  2023.  Density-dependent

            selection.  Annual Review of Ecology, Evolution, and Systematics 54:85-105.

Gatto, J. V. and J. Travis.  2024.  Different patterns of coupled predator-prey dynamics when

            the same species interact in different locations.  Oecologia 205:461-471.

Skrob-Martin, S., J. Travis, and S. A. Southerland. 2024. Fossils, DNA, and nothing: evidence

            of evolutionary biology university students find compelling.  Evolution: Education

            and Outreach 7:21

Morrison, K., J. J. Zuniga-Vega, J. Travis, and D. Reznick.  2025.  The evolution of a placenta

            accelerates the evolution of post-copulatory reproductive isolation.  Evolution

            79:457-466.

Travis, J.  2025. Life history in the context of predator-prey interactions. Chapter 12 in M.

            Segoli and E. Wajnberg, eds., Life History Evolution: Traits, Interactions, and

            Applications.  Wiley and Sons, New York, 364pp.

Pluer, B. D. and J. Travis. 2025. The digestive microbiome of the Least Killifish, Heterandria

            formosa, and its implications for host adaptability to varying trophic levels.

            Environmental Microbiology Reports 17:e70164.

Pluer, B. D., Macrae, P. S. D., and J. Travis.  2025. Intraspecific variation in elemental

            composition of the Least Killifish tracks spatial variation in periphyton composition.

            Ecology and Evolution 15: e72326 

Arendt, J., J. Travis, and D. N. Reznick. 2025. On measurements of parallel phenotypic

            evolution. American Naturalist 206:198-205.

Reznick, D. and J. Travis.  2026. Evolution: plants vs. animals or sexual conflict?  Current

            Biology 36: R66-R69. 

Potter, T., R. Mohammed, J. Goldberg, D. Reznick, J. Travis, and R. Bassar.  2026.  Parasites

            alter host community structure in a natural experiment.  J. Animal Ecology 95:1059-

            1071.

Travis, J. 2026. The Triumph of Biology’s Model Organisms: How Flies, Mice, and Slime Molds Became Teachers of Biology. Academic Press, London. xix + 193 pp.