Department of Biological Science

Biological Science Faculty Member

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

Research and Professional Interests:

My research revolves around understanding how ecological processes drive evolutionary ones and, sometimes, vice-versa. My research is focused on how and why features of animals and plants vary from one population to another.  When this variation has a genetic basis, it represents the earliest stage in the adaptive generation of biodiversity.  This variation can also generate differences in local ecological processes, thereby creating correlated differences among locations in evolutionary trajectories and ecological relationships. 

For example, populations of Trinidadian guppies at higher elevations of mountain streams have diverged 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 pressure on guppies at high elevations, produce natural selection that favors 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.  Through their differences in diet and the distribution of body sizes, these two phenotypes of guppies have different effects on the algae and invertebrates in their habitat and thereby cause a striking difference in community and ecosystem organization. 

I am particularly interested in the process of density-dependent selection.  For one reason, it offers an interesting challenge for understanding local adaptation. For example, changes in predation pressure from one population to another usually produce changes in numerical density as well.  This is obviously true in the guppy populations and ascertaining whether differences in predation pressure or differences in density were the driving force of selection was no easy task.  For another reason, evolution under density-dependent selection will usually minimize a population's susceptibility to the negative effects of increased density on population growth rate and thereby change population parameters like the carrying capacity and, perhaps, the stability of that population's numerical dynamics.  These changes will, in turn, affect other aspects of community and ecosystem organization.   

With one foot in ecology and another in evolutionary biology, I have guided students in a diversity of research projects. My graduate 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 all of these projects is an immense curiosity about nature and the determination to find answers to important questions regardless of the path to those answers.

Selected Publications:

Culumber, Z. W., J. M. Anaya-Rojas, W. W. Booker, A. Hooks, E. C.Lange, B. Pluer, N. Ramirez-Bullon, J. Travis.  2019. Widespread biases in ecological and evolutionary studies.  Bioscience (in press).

Reznick, D., R.D. Bassar, C. Handelsman, C. K. Ghalambor, J. Arendt, T. Coulson, T. Potter, E. W. Ruell, J. Torres-Dowdall, P. Bentzen, J. Travis.  2019.  Eco-evolutionary feedbacks predict the time course of rapid life history evolution.  Am. Nat. (in press).

Goldberg, D. L., J. A. Landy, J.Travis, M. S. Springer, and D. Reznick. 2019.  In love and war: the morphometric and phylogenetic basis of ornamentation and the evolution of male display behavior in the livebearer genus Poecilia.  Evolution 73:360-377.

Reznick, D. N., J. Losos, and J. Travis. 2019. From low to high gear: there has been a paradigm shift in our understanding of evolution.  Ecology Letters 22:233-244.

Potter, T., L. King, J. Travis, and R. D. Bassar. 2019. Competitive asymmetry and local adaptation in Trinidadian guppies.  J. Animal Ecology 88:330-342.

Simon, T. N., A. J. Binderup, A. S. Flecker, J. F. Gilliam, M. C. Marshall, S. A. Thomas, J. Travis, D. N. Reznick, C. M. Pringle. 2019. Landscape patterns in top-down control of decomposition: omnivorous fish decouples a detrital-based trophic cascade in a tropical stream.  Ecology 100: UNSPe02723.

 Leatherbury, K. and J. Travis. 2019. The effects of food level and social density on reproduction in the Least Killifish, Heterandria formosa.  Ecology and Evolution 9:100-110.

Landy, J. A. and J. Travis. 2018. Unique maternal and environmental effects on the body morphology of the Least Killifish, Heterandria formosa.  Ecology and Evolution 8:6265-6279.

Levell, S. and J. Travis. 2018. Activity level and predation risk in the Least Killifish, Heterandria formosa.  Copeia 106:436-442.

Kraft, B., V. A. Lemakos, J. Travis, and K. A. Hughes. 2018. Pervasive indirect genetic effects on behavioral development in polymorphic eastern mosquitofish.  Behavioral Ecology 29:289-300.

Culumber, Z. W., B. Kraft, V. Lemakos, E. Hoffner, J Travis, and K. A. Hughes. 2018. GxG epistasis in growth and condition and the maintenance of genetic polymorphism in Gambusia holbrooki. Evolution 72:1146-1154.

Bassar, R. D., J. Travis, and T. Coulson. 2017. Predicting coexistence in species with continuous ontogenetic niche shifts and competitive asymmetry. Ecology 98:2823-2836.

Bassar, R.D., T. Simon, W. Roberts, J. Travis, and D. Reznick. 2017. The evolution of coexistence: reciprocal adaptation promotes the assembly of a simple community. Evolution 71:373-385.

Kraft, B., E. Williams, V. Lemakos, J. Travis, and K. A. Hughes. 2016. Genetic color morphs in the eastern mosquitofish experience different social environments in the wild and in the lab. Ethology 122:869-880.

Bassar, R. D., B. L. Bryan, M. C. Marshall, C. M. Pringle, D. Reznick, and J. Travis. 2016. Local adaptation of fish consumers alters primary production through changes in algal community composition and diversity. Oikos 126:594-603.

Landy, J. A. and J. Travis. 2015. Shape variation in the Least Killifish: ecological associations of phenotypic variation and the effects of a common garden. Ecology and Evolution 5:5616-5631.

Warwick, A. R., J. Travis, and E. M. Lemmon. 2015. Geographic variation in the Pine Barrens treefrog (Hyla andersoni): concordance of genetic, morphometric, and acoustic signal data. Molecular Ecology 24:3281-3298.

Gallo, S. A., A. S. Carpenter, D. Irwin, C. D. McPartland, J. Travis, S. Reynders, L. A. Thompson, and S. R. Glisson. 2014. The validation of peer review through research impact measures and the implications for funding strategies.  PLoS ONE 9:e106474.

Travis, J., D. Reznick, R. D. Bassar, A. Lopez-Sepulcre, R. Ferriere, and T. Coulson. 2014. Do eco-evo interactions help us understand nature? Answers from the study of the Trinidadian guppy. Advances in Ecological Research 50:1-40.

Postdoctoral Associates:

Graduate Students: