Morris Laboratory Publications

Image of Multilineatus fish


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. (

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. (

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.

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.

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

Weinstein M., Liotta M.N., Solitt A., Hunt A., Abbott J.K., Rios-Cardenas O., and Morris M.R. (2019) Selection on growth rates to increase survival to sexual maturity and longevity in the swordtail fish Xiphophorus multilineatus. Evolutionary Ecology

Morris MR, Friebertshauser RJ, Zupi M, Liotta MN, Dunn G, Kleinas N and Ríos-Cardenas O (2018) Feeding Rates in the Swordtail Fish Xiphophorus multilineatus: A Model System for Genetic Variation in Nutritional Programming. Zebrafish 2018

Ríos-Cardenas O, Bono L, Morris MR (2018) Frequency-dependent selection and fluctuations around an equilibrium for alternative reproductive tactics in a swordtail. Animal Behaviour 140, 19-28.

Lu, Y., Klimovich, C., Robeson, K., Boswell, W., Rios-Cardenas, O., Walter, R.B., Morris, M.R. (2017) Transcriptome assembly and candidate genes involved in nutritional. programming in the swordtail fish Xiphophorus multilineatus PeerJ, 5, e3275

Morris, M.R., Ludwar L.C., Swingle, E., Mamo, M.N., and Shubrook, J.H. (2016) “A new method to assess asymmetry in fingerprints can be used as an early indicator of type 2 diabetes mellitus” Diabetes Science and Technology. DOI: 10.1177/1932296816629984

Morris, M.R., R.J. Friebertshauser, O. Rios-Cardenas, M.N. Liotta and J.K. Abbott (2016) Selection on growth rates across alternative reproductive tactics in the swordtail Xiphophorus multilineatus. Evolutionary Ecology 30 (3), 519-533.

D’Amore, D.M., Rios-Cardenas, O. and Morris, M.R. (2015) Maternal investment influences development of a behavioral syndrome in swordtail fish, Xiphophorus multilineatusAnimal Behaviour 103, 147-151.

Lyons, S.M., Goedert, D., and Morris, M.R. (2014). Male-trait-specific variation in female mate preferences. Animal Behaviour, 87, 39-44.

Murphy, A., Goedert, D. and Morris, M.R. (2014) Maternal effects are long lasting and influence female offspring’s reproductive strategy in the swordtail fish Xiphophorus multilineatus. Journal of Evolutionary Biology

Morris, M. R., Goedert, D., Abbott J.K., Robinson D.M. and Rios-Cardenas O. (2013) Intralocus tactical conflict and the evolution of alternative reproductive tactics. Advances in the Study of Behavior 45, 447-47858.

Morris, M.R. and Rios-Cardenas, O. (2013). Underestimating the role of female preference and sexual conflict in the evolution of ARTs in fishes: Insights from a clade of Neotropical fishes. In: Sexual Selection: Insights from the Neotropics(Regina H. F. Macedo and Glauco Machado, Editors).

Rios-Cardenas, O., Brewer, J., and Morris, M.R. (2013). Maternal Investment in the Swordtail Fish Xiphophorus multilineatus: support for the differential allocation hypothesis. PloS one, 8(12), e82723.

Rios-Cardenas O. and Morris M.R. (2012). The implications of variation in female preferences for swordtail fishes. In: Viviparous Fishes II, the proceedings of the III International Symposium on Viviparous Fishes. M.C. Uribe & H.J. Grier, editors. New Life Publications, Homestead, USA

Morris, M. R., Rios-Cardenas, O., Lyons, S., Tudor, M.S. and Bono, L. (2012). Fluctuating asymmetry indicates optimization of growth rate over developmental stability. Functional Ecology, 26, 23-731. Bono, L.M., Rios-Cardenas, O. and Morris, M.R. (2011). Alternative life history strategies in Xiphophorus multilineatus: Evidence for different ages to sexual maturity but not growth rates in the wild. Journal of Fish Biology 78, 1311-1322.

Rios-Cardenas, O. and Morris, M.R. (2011) Precopulatory Sexual Selection in Poeciliidae. Chapter 17 in: Ecology and Evolution of Poeciliid Fishes (editors: Jon Evans, Andrea Pilastro & Ingo Schlupp) University of Chicago Press, Chicago USA.

Robinson, D. Tudor, M.S and Morris M.R. (2011) Female preference and the evolution of an exaggerated male ornament: the shape of the preference function matters. Animal Behaviour 81, 1015-1021.

Tudor M.S. and Morris M.R. (2011) Frequencies of alternative mating strategies influence female mate preference in the swordtail Xiphophorus multilineatusAnimal Behaviour 82, 1313-1317.

Morris, M. R., Rios-Cardenas, O. and Brewer, J. (2010) Variation in mating preference within a wild population influences the mating success of alternative mating strategies. Animal Behavior 79, 773-678.

Tudor, M. S. and Morris, M. R (2009) Does male mate preference in the swordtail Xiphophorus malinche influence variation in female preference for symmetry? Animal Behaviour 146, 727-740.

Tudor, M. S. and Morris, M. R. (2009) Experience plays a role in female preference for symmetry in the swordtail fish Xiphophorus malincheEthology 115, 812-822.

Lyons, S. and Morris, M. R. (2008) Headstands: a sexually selected signal in the swordtail fish Xiphophorus nezahualcoyotl Behaviour 145, 1247-1262.

Morris, M. R., Rios-Cardenas, O. and Darrah, A. (2008) Male mating tactics in the Northern Mountain Swordtail fish (Xiphophorus nezahualcoyotl): coaxing and coercing females to mate. Ethology 114:977-988.

Fernandez, A. A. and Morris, M. R. (2008) Mate choice for more melanin as a mechanism to maintain a functional oncogene. Proceedings of the National Academy of Science, 105, 13503-13507.

Gerl, E.J. and Morris, M.R. (2008) The Causes and Consequences of Color Vision Evolution: Education and Outreach

Gutiérrez-Rodríguez, C., Shearer, A., Morris, M. R., and de Queiroz, K. (2008). Phylogeography and monophyly of the swordtail fish species Xiphophorus birchmanni (Cyprinodontiformes, Poeciliidae). Zoologica Scripta. 37:129-139.

Morris, M. R., Tudor, S. M. and Dubois, N. S. (2007). Sexually selected signal attracted females prior to deterring aggression in rival males. Animal Behavior, 74, 1189-1197.

Rios-Cardenas, Tudor, M. S. and Morris, M. R. (2007) Variation in female preference has implications for the maintenance of an alternative mating strategy in a swordtail fish. Animal Behaviour 74, 633-640.

Fernandez, A. A. and Morris, M. R. (2007). Sexual Selection and Trichromatic Color Vision in Primates: Statistical Support for the Pre-existing Bias Hypothesis. American Naturalist 170, 10-20.

Just, W., Morris, M. R., and Sun, X. (2007) The evolution of aggressive losers. Behavioural Processes 74, 342-350.

Gutiérrez-Rodríguez, C. Morris, M. R., Dubois, N. S. and de Queiroz, K. (2007) Genetic variation and phylogeography of the swordtail fish Xiphophorus cortezi(Cyprinodontiformes, Poeciliidae). Molecular Phylogenetics and Evolution 43, 111-123.

Moretz, J. A. and Morris, M. R. (2006) Phylogenetic Analysis of the Evolution of a Signal of Aggressive Intent in Northern Swordtail Fishes. American Naturalist 168, 336–349.

Wiegmann, D. D. and Morris, M. R. (2006) Search Behavior and Mate Choice. Recent Advances in Experimental and Theoretical Biology 1, 201-216.

Morris, M. R., Cardenas-Rio, O. and Tudor, M. S. (2006) Larger swordtail females prefer asymmetrical males. Biology Letters Royal Society of London 2, 8-11.

Morris, M. R., Moretz, J. A., Farley, K. and Nicoletto, P. (2005) The Role of Sexual Selection in the Loss of Sexually Selected Traits in the Swordtail Fish Xiphophorus continens. Animal Behaviour 69, 1415-1424.

Just, W. and Morris, M. R. (2003) The Napoleon Complex: Why Smaller Males Pick Fights. Evolutionary Ecology 17, 509-522.

Moretz, J. A., Morris, M. R (2003) Evolutionarily Labile Responses to a Conventional Threat Signal. Proceedings of the Royal Society, London B 270, 2271-2277.

Hankison, S. J. and Morris, M. R. (2003) Avoiding a compromise between sexual selection and species recognition: female swordtail fish assess multiple species-specific cues. Behavioral Ecology 14, 282-287.

Morris, M. R. Hesselman, L. and Nicoletto, P. (2003) A Polymorphism in female preference for a polymorphic male trait in the swordtail Xiphophorus cortezi. Animal Behaviour 65(1), 45-52.

Hankison, S.J. and Morris, M.R. (2002) Sexual selection and species identification in Xiphophorus pygmaeus: conflicting preferences. Behavioral Ecology and Sociobiology 51, 140-145.

Morris, M.R., Elias, J. A. and Moretz, J. A. (2001) Defining the sexually selected male trait vertical bars in relation to female preference in the swordtail fish Xiphophorus corteziEthology 107, 827-837.

Dries, L., Morris, M.R. and Ryan, M. J. (2001) Why are some male pygmy swordtails large? Copeia 2001, 355-364.

Morris, M. R., de Queiroz, K. and Morizot, D. (2001) Phylogenetic relationships among the Northern Swordtails (Xiphophorus) as inferred from allozyme data. Copiea 2001, 65-81.

Merry, J. W. and Morris, M. R. (2001) Preference for symmetry in swordtail fish. Animal Behavior 61, 477-479.

Hoefler, C. H. and Morris, M. R. (1999) A technique for the temporary application and augmentation of pigment patterns in fish. Ethology 105, 431-438.

Morris, M. R. (1998) Further examination of female preference for vertical bars in swordtails: preference for "no bars" in a species without bars. Journal of Fish Biology Supplement A to Volume 53, 57-64.

Morris, M. R. (1998) Female Preference for Trait Symmetry in Addition to Trait Size in Swordtail Fishes. Proceedings of the Royal Society, B.1399, 907-911.

Morris, M. R. and Casey, K. (1998) Female swordtail fish prefer symmetrical sexual signal. Animal Behaviour 55, 33-39.

Morris, M. R., Wagner Jr., W.E. and Ryan, M. J. (1996). A negative correlation between trait and mate preference in Xiphophorus pygmaeusAnimal Behaviour52, 1193-1203.

Morris, M. R. and Ryan, M. J. (1996) Sexual difference in sender-receiver coevolution. Animal Behaviour 52, 1017-1024.

Wiens, J.J. and Morris, M.R. (1996) Sexual selection and the evolution of swords. American Naturalist, 147 866-869.

Morris, M.R., Gass, L. & Ryan, M.J. (1995). Assessment and individual recognition of opponents in the swordtails Xiphophorus nigrensis and Xiphophorus multilineatus. Behavioral Ecology and Sociobiology 37, 303-310.

Morris, M.R., Mussel, M. and Ryan, M. J. (1995) Vertical body bars on male X. multilineatus: a signal that deters rival males and attracts females. Behavioral Ecology 6, 274-279.

Morris, M.R. and Ryan, M.J. (1995) Large body size in the pygmy swordtail Xiphophorus pygmaeus. Biological Journal of the Linnaean Society 54, 383-395.

Morris, M.R., Batra, P., and Ryan, M.J. (1992) Male-male competition and access to females in the swordtail Xiphophorus nigrensisCopeia 1992, 980-986.

Morris, M.R. and Ryan, M.J. (1992) Breeding cycles in natural populations of Xiphophorus nigrensisX. multilineatus, and X. pygmaeusCopeia, 1074-1077.

Ryan, M.J., Pease, C.E. and Morris, M.R. (1992) Maintenance of a genetic polymorphism in the swordtail Xiphophorus nigrensis: A general life history model. American Naturalist 139, 21-31.

Gardner, R. & Morris, M.R. (1991) The evolution of bluffing in animal contests: an extended model. In: Game Equilibrium Models I: Evolution and Game Theory. Ed. Selten, R. pp 182-194. Springer-Verlag, Berlin.

Morris, M.R. (1991) Mating behaviour in the treefrog Hyla ebraccataJournal of Zoology 223, 371-378.

 Morris, M.R. & Ryan M.J. (1990) Age at sexual maturity of male Xiphophorus nigrensis in nature. Copeia 1990, 747-751.

Morris, M.R. (1989) Female choice and selection for male size in the treefrog Hyla chrysoscelisBehavioral Ecology and Sociobiology 25, 275-281.

Gardner, R. & Morris, M.R. (1989) The evolution of bluffing in animal contests: an ESS approach. Journal of Theoretical Biology 137, 235-243.

Morris, M.R. & Yoon, S.L. (1989) A mechanism for female choice of large males in the treefrog Hyla chrysoscelisBehavioral Ecology and Sociobiology, 25, 65-71.

Gardner, R., Morris, M.R. and Nelson, C.E. (1987) Conditional evolutionarily stable strategies. Animal Behaviour 35, 507-519.

Other publications:

Morris, M. R. (2009) Book Review. Fish Behaviour by Carin Magnhagen, Science Publishers, Quarterly Review of Biology

Rios-Cardenas O. and Morris M. R. (2008) Mating systems and strategies of tropical fish. In : International Commission on Tropical Biology and Natural Resources (Eds. Claro, K., Oliveira, P.S. , Gray, V. et al.), Encyclopedia of Life Support Systems (EOLSS), Developed under the auspices of the UNESCO, EOLSS Publishers, Oxford , UK.

Macedo, R.H., & Morris, M. R. 2008. Introduction to Tropical Zoology. In : International Commission on Tropical Biology and Natural Resources (Eds. Claro, K., Oliveira, P.S. , Gray, V. et al.), in Encyclopedia of Life Support Systems (EOLSS), Developed under the auspices of the UNESCO, EOLSS Publishers, Oxford , UK.

Rios-Cardenas O. and Morris M. R. (2007). The implications of variation in female preferences for swordtail fishes. In: Viviparous Fishes II, the proceedings of the III International Symposium on Viviparous Fishes.

Morris, M.R. (2005) Book Review. Animal Signals by Maynard Smith, J. & Harper, D. Oxford Series in Ecology and Evolution, Oxford University Press, New York. Ethology 111-10, 1071-1072.

Wiens, J.J and Morris M.R. (2003) Book Review. Sexual Selections by M. Zuk, Quarterly Review of Biology 78, 127.

Morris, M.R. (1996) Book Review. Amphibian BiologyVolume 2, Social Behavior(Editors Heatwole, H. and Sullivan, B.) Herpetological Review, 27, 220-221.

Greig, N. and Morris, M. (1992) eds. Tropical Biology: An Ecological Approach 92-1. Organization for Tropical Studies, Inc., Duke University, Durham, NC