John Fitzpatrick

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John Fitzpatrick

Biträdande lektor, Docent


Zoologiska institutionen: Etologi
08-16 26 21
08-15 95 22
Svante Arrhenius väg 18b
D 5012b
Stockholms universitet
Zoologiska institutionen: Etologi
106 91 Stockholm


I am an evolutionary biologist who specializes in studying sexual selection and the evolution of reproductive behaviours and traits. Research in my lab takes an interdisciplinary approach and investigates male-male competition before and after mating, the evolution of sexual weapons, female mate choice, trade-offs and co-evolutionary dynamics.

My research is both field and lab based and combines tightly controlled experiments with phylogenetic comparative analyses. But generally I prefer to mix these approaches depending on the research question being asked.



Females mate with multiple males in most animal species, which has important evolutionary consequences. We are using phylogenetic comparative analyses to explore how variation in female promiscuity influences the evolution of male sexual behaviours and traits. This work focuses on sharks, rays, Tanganyikan cichlids, and fishes generally, social insects, marine mammals, and mammals generally. We are currently exploring how co-evolutionary dynamics between males and females influence the evolution of testes, sperm, genitals and female remating rates.


When it comes to sex you can’t have it all. Animals must balance their investment in behaviours and traits important before and after mating. My lab tries to understand how animals balance the competing demands of sex by exploring macro-evolutionary patterns across a wide range of taxonomic groups and experimentally using guppies and crickets.


Not all males use the same behaviours to reproduce. In some species, larger males court and guard females to secure fertilizations, while other smaller sneaker males perform sneaky fertilizations. Research in my lab examines the reproductive consequences of these different mating behaviours, focusing on African cichlids, freshwater gobies and intertidal marine fish.


We have projects available studying trade-offs in sexually selected behaviorus and traits in halfbeak fish, as well as a broad range of comparative studies focusing on sexual selection. If you are interested in joining my lab at the Masters, PhD or Post-doc level please send me an email explaining your research interests.


2014-Present: Editor for Behavioral Ecology
2011-2015: Board of Reviewing Editors for Journal of Evolutionary Biology


You can find a full list of my publications here:
Fitzpatrick GoogleScholar



Alessandro Devigili, Jonathan P. Evans, John L. Fitzpatrick. 2019. Predation shapes sperm performance surfaces in guppies. Proceedings of the Royal Society of London, Series B, Biological Sciences 286.

Miriam Fenkes, John L. Fitzpatrick, Holly A. Shiels, Robert L. Nudds. 2019. Acclimation temperature changes spermatozoa flagella length relative to head size in brown trout. Biology Open 8.

Jessica S. Miller, Aneesh P. H. Bose, John L. Fitzpatrick, Sigal Balshine. 2019. Sperm maturation and male tactic-specific differences in ejaculates in the plainfin midshipman fish Porichthys notatus. Journal of Fish Biology 94: 434-445.

Leigh W. Simmons, John L. Fitzpatrick. 2019. Female genitalia can evolve more rapidly and divergently than male genitalia. Nature Communications 10.

Amy G. Rowley, Toby S. Daly-Engel, John L. Fitzpatrick. 2019. Testes size increases with sperm competition risk and intensity in bony fish and sharks. Behavioral Ecology 30: 364-371.

Amy Rowley, Lisa Locatello, Ariel Kahrl, Mariana Rego, Annika Boussard, Eduardo Garza-Gisholt, Ryan M. Kempster, Shaun P. Collin, Eva Giacomello, Maria C. Follesa, Cristina Porcu, Jonathan P. Evans, Fabio Hazin, Francisco Garcia-Gonzalez, Toby Daly-Engel, Carlotta Mazzoldi, John L. Fitzpatrick. 2019. Sexual selection and the evolution of sperm morphology in sharks. Journal of Evolutionary Biology 32: 1027-1035.

Christina Hansen Wheat, John L. Fitzpatrick, Björn Rogell, Hans Temrin. 2019. Behavioural correlations of the domestication syndrome are decoupled in modern dog breeds. Nature Communications 10.

John L. Fitzpatrick, Erica L. Larson. 2018. Finding Sperm in the English Countryside - The 14th Biology of Spermatozoa Meeting. Molecular Reproduction and Development 85: 371-373.

Graeme Fox, Iulia Darolti, Jean-Denis Hibbitt, Richard F. Preziosi, John L. Fitzpatrick, Jennifer K. Rowntree. 2018. Bespoke markers for ex-situ conservation - application, analysis and challenges in the assessment of a population of endangered undulate rays. Journal of Zoo and Aquarium Research 6: 50-56.

Alessandro Devigili, John L. Fitzpatrick, C. Gasparini, I. W. Ramnarine, A. Pilastro, J. P. Evans. 2018. Possible glimpses into early speciation - the effect of ovarian fluid on sperm velocity accords with post-copulatory isolation between two guppy populations. Journal of Evolutionary Biology 31: 66-74.

Christina Hansen Wheat, John Fitzpatrick, Ingrid Tapper, Hans Temrin. 2018. Wolf (Canis lupus) Hybrids Highlight the Importance of Human-Directed Play Behavior During Domestication of Dogs (Canis familiaris). Journal of comparative psychology (1983) 132: 373-381.

Miriam Fenkes, John L. Fitzpatrick, Karlina Ozolina, Holly A. Shiels, Robert L. Nudds. 2017. Sperm in hot water - direct and indirect thermal challenges interact to impact on brown trout sperm quality. Journal of Experimental Biology 220: 2513-2520.

Cody J. Dey, Constance M. O'Connor, Holly Wilkinson, Susanne Shultz, Sigal Balshine, John L. Fitzpatrick. 2017. Direct benefits and evolutionary transitions to complex societies. Nature Ecology and Evolution 1.

Leigh W. Simmons, Stefan Lüpold, John L. Fitzpatrick. 2017. Evolutionary Trace-Off between Seconcary Sexual Traits and Ejaculates. Trends in Ecology & Evolution 32: 964-976.

Leigh W. Simmons, John L. Fitzpatrick. 2016. Sperm competition and the coevolution of pre- and postcopulatory traits - Weapons evolve faster than testes among onthophagine dung beetles. Evolution 70: 998-1008.

John L. Fitzpatrick, J. P. Evans. 2014. Postcopulatory inbreeding avoidance in guppies. Journal of Evolutionary Biology 27: 2585-2594.

Luisa J. Fitzpatrick, Clelia Gasparini, John L. Fitzpatrick, Jonathan P. Evans. 2014. Male-female relatedness and patterns of male reproductive investment in guppies. Biology Letters 10.

Stefan Lüpold, Joseph L. Tomkins, Leigh W. Simmons, John L. Fitzpatrick. 2014. Female monopolization mediates the relationship between pre- and postcopulatory sexual traits. Nature Communications 5.

Jennifer L. Kelley, John L. Fitzpatrick, Sami Merilaita. 2013. Spots and stripes - ecology and colour pattern evolution in butterflyfishes. Proceedings of the Royal Society of London, Series B, Biological Sciences 280.

J. L. Fitzpatrick, Maria Almbro, A. Gonzalez-Voyer, S. Hamada, C. Pennington, J. Scanlan, Niclas Kolm. 2012. Sexual selection uncouples the evolution of brain and body size in pinnipeds. Journal of Evolutionary Biology 25: 1321-1330.

J. L. Fitzpatrick, Maria Almbro, A. Gonzalez-Voyer, Niclas Kolm, L. W. Simmons. 2012. Male Contest Competition And The Coevolution Of Weaponry And Testes In Pinnipeds. Evolution 66: 3595-3604.

John L Fitzpatrick, Boris Baer. 2011. Polyandry reduces sperm length variation in social insects. Evolution 65.

John L. Fitzpatrick, Robert Montgomerie, Julie K. Desjardins, Kelly A. Stiver, Niclas Kolm, Sigal Balshine. 2009. Female promiscuity promotes the evolution of faster sperm in cichlid fishes. Proceedings of the National Academy of Sciences of the United States of America 106: 1128-1132.

J L Fitzpatrick, J K Desjardins, N Milligan, K A Stiver, R Montgomerie, S Balshine. 2008. Female-mediated causes and consequences of status change in a social fish. Proceedings of the Royal Society of London, Series B, Biological Sciences 275.

Alejandro Gonzalez-Voyer, John L. Fitzpatrick, Niclas Kolm. 2008. Sexual selection determines parental care patterns in cichlid fishes. Evolution 62: 2015-2026.

Övrigt vetenskapligt

Christina Hansen Wheat, John Fitzpatrick, Ingrid Tapper, Hans Temrin. Wolf (Canis lupus) hybrids highlight the importance of human-directed play behavior during domestication of dogs (Canis familiaris).

Christina Hansen Wheat, John Fitzpatrick, Hans Temrin. Behavioural correlations of the domestication syndrome are decoupled in modern dog breeds.