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Molly R. Morris

Molly R. Morris, portrait
Life Science Building 243

Molly Morris in OHIO News

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Ph.D., Indiana University

Courses Taught

  • BIOS 3300 Principles of Evolution
  • BIOS 4930/5930 Animal Behavior
  • BIOS 6930 Behavioral Ecology

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.


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.

Representative Publications

Fitschen-Brown, M., Morris M.R. (2023) Genotype and growth rates influence female mate preferences in Xiphophorus multilineatus: potential selection to optimize mortality-growth rate tradeoff. Plos One

Stec, H., Gambill, M., Whitmer, H., Tompkins, K. Rios-Cardenas, O., Morris, M.R. (2023) Physiological cost to behavioral plasticity in a swordtail fish: clues to its evolutionary loss. Animal Behavior, 201, 167-174.

Preising, G.A., Gunn, T., Baczenas, J.J., Pollock, A., Powell, D.L., Dodge, T.O., Angel J., Kairuz, M., Savage, M., Lu, Y., Fitschen-Brown, M., Cummings, M., Thakur, S.,  MichaTobler, M., Ríos-Cardenas, O., Morris, M.R., Schumer M. (2022) Recurrent evolution of small body size and loss of the sword ornament in Northern Swordtail fish. bioRxiv

Fitschen-Brown, M., Tudor, M. S., Hamlin, H., Morris M.R. (2022) Higher Cortisol in Muscle Correlates with Weaker Strength of Female Mate Preference in Swordtail Fish, Xiphophorus multilineatus. Animal Behavior 187, 63-69.

Liotta, M.N., Kamara, S., Abbot, J.K, Rios-Cardenas, O., Morris, M.R. (2021) Evidence for Genetic Integration of Mating Behavior and Morphology in a Behaviorally Plastic Alternative Reproductive Tactic. Evolutionary Ecology, 35, 723-737.

Tompkins, K., Lott, M.S., Rios-Cardenas, O., Jash, S., Morris, M.R. (2021) Metabolic-growth hypothesis for the evolution of the nuchal hump fat deposit in swordtail fishes. Environmental Biology of Fishes, 104, 1195-1206.

Liotta, M.N., Abbot, J.K, Morris M.R., Rios-Cardenas O. (2021) Antagonistic selection on body size and sword length in a wild population of the swordtail fish, Xiphophorus multilineatus:potential for intralocus tactical conflict. Ecology and Evolution. 11, 3941-3955. (

Griebling, H., Rios-Cardenas O., Abbot, J., Morris M.R. (2020) A study of tactical and sexual dimorphism in cognition with insights for sexual conflict. Animal Behaviour. 170, 43-50.

D'Amore, D. M., Popescu, V. D., & Morris, M. R. (2019) The influence of the invasive process on behaviours in an intentionally introduced hybrid, Xiphophorus helleri–maculatus. Animal Behaviour, 156, 79-85.

Abbott J.K., Rios-Cardenas O., Morris M.R. (2019a) Invited Review: Insights from Intralocus Tactical Conflict: adaptive states, interactions with ecology and population divergence. Perspectives, Oikos 128 (11), 1525-1536. (Highlighted as Editor’s Choice).

Abbott J.K., Rios-Cardenas O., Morris M.R. (bioRxiv, September 2019b) Genetic correlations across genetically determined and developmentally plastic alternative reproductive tactics.

Liotta, M.R., Abbott, J.K., Rios-Cardenas, O., Morris, M.R. (2019) Tactical dimorphism in body shape and the correlation with mating behaviors in the swordtail Xiphophorus multilineatus. Biological Journal of the Linnean Society, 127(2), 337-350.