Molly R. Morris

I received a B.A. from Earlham College in 1978 and a Ph.D. from Indiana University in 1987. After a postdoctoral fellowship at University of Texas, Austin, I held faculty positions at the University of Maryland Eastern Shore and Montgomery College, before accepting my current position in the Biological Sciences Department at Ohio University. I am a Fellow of the Animal Behavior Society and have served as Secretary and President for the society. I also served as Associate Editor for the journal Behaviour and Editor for the journal Animal Behavior.

Molly Morris in OHIO News

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Research Interests

My research interests are in sexual selection, variation in female mate preferences, and the evolution of alternative reproductive strategies. In my laboratory, we are interested in the evolutionary processes that both constrain and drive biological diversity. We examine the evolution of diversity both within and across species of Xiphophorus fishes. These small livebearing fish, native to freshwater streams in Mexico, present a diversity of behaviors and morphologies that are ideal for examining the evolution of behavioral plasticity, female mate preferences, nutritional programming, maternal effects, and the evolution of alternative reproductive strategies. We observe behavior in the field as well as in the laboratory, incorporating molecular techniques to conduct paternity analyses and examine gene expression profiles.

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Representative Publications

Aguillon, S. M., S. K. Haase Cox, Q. K. Langdon, T. R. Gunn, J. J. Baczenas, S. M. Banerjee, A. E. Donny, et al. 2025. "Pervasive Gene Flow Despite Strong and Varied Reproductive Barriers in Swordtails." Nature Ecology and Evolution, 1–12.

Cobb, N. E., S. M. Mason, K. Tompkins, M. Fitschen-Brown, O. Rios-Cardenas, and M. R. Morris. 2024. "Variation in the Strength of Female Mate Preferences Support the Signal Reliability Hypothesis." PLoS ONE 19 (6): e0303691.

Dodge, T. O., M. R. Morris, M. Schartl, D. L. Powell, and M. Schumer. 2024. "Complex Structural Variation and Behavioral Interactions Underpin a Balanced Sexual Mimicry Polymorphism." Current Biology 34 (20): 4662–4676.

Fitschen-Brown, M., S. Kamara, M. Parker, K. Daniels, A. L. Gilbert, and M. R. Morris. 2026. "Chronic Exposure to Nitrate Alters Aggression and Boldness in the Swordtail Fish, Xiphophorus helleri." Animal Behavior.

Fitschen-Brown, M., and M. R. Morris. 2023. "Genotype and Growth Rates Influence Female Mate Preferences in Xiphophorus multilineatus: Potential Selection to Optimize Mortality-Growth Rate Tradeoff." PLoS ONE 18 (6): e0287843.

Langdon, Q. K., J. S. Groh, M. A. Stepfanie, D. L. Powell, T. Gunn, P. Payne, J. J. Baczenas, et al. 2024. "Genome Evolution Is Surprisingly Predictable After Initial Hybridization." PLoS Biology 22 (8): e03002742. https://doi.org/10.1371/journal.pbio.3002742.

Maldonado-Sánchez, D., O. Rios-Cardenas, M. R. Morris, and C. Gutiérrez-Rodríguez. 2025. "Phylogeography and Demographic History of the Swordtail Fish Xiphophorus multilineatus." Environmental Biology of Fishes.

Preising, G. A., T. Gunn, O. Rios-Cardenas, M. R. Morris, and M. Schumer. 2024. "Recurrent Evolution of Small Body Size and Loss of the Sword Ornament in Northern Swordtail Fish." Evolution 78 (12): 2017–2031.

Stec, H., M. Gambill, H. Whitmer, K. Tompkins, O. Rios-Cardenas, and M. R. Morris. 2023. "Physiological Cost to Behavioral Plasticity in a Swordtail Fish: Clues to Its Evolutionary Loss." Animal Behavior 201: 167–174.

Tompkins, K., W. Boswell, K. Du, X. Lai, Y. Lu, and M. R. Morris. 2025. "Composition and Function of the Nuchal Hump of Male Xiphophorus multilineatus." Fish Physiology and Biochemistry 51: 130.

Tompkins, K., D. B. Miles, and M. R. Morris. 2026. "Predicting Responses to Warming Temperatures for the Growth, Size and Age at Sexual Maturity in Male Xiphophorus multilineatus." PeerJ.