Sexual Dimorphism in Fin Size and Shape in North American Killifish

ABSTRACT Sexual dimorphism is intriguing because it suggests that males and females differ in phenotypic optima for traits and that sex‐specific trait values can evolve despite a shared genome. Differences in sexual dimorphism across populations or species suggest that the nature of sexual selection...

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Main Authors: Elijah J. Davis, Kasey Brockelsby, Milton Tan, Rebecca C. Fuller
Format: Article
Language:English
Published: Wiley 2025-04-01
Series:Ecology and Evolution
Subjects:
Online Access:https://doi.org/10.1002/ece3.71194
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author Elijah J. Davis
Kasey Brockelsby
Milton Tan
Rebecca C. Fuller
author_facet Elijah J. Davis
Kasey Brockelsby
Milton Tan
Rebecca C. Fuller
author_sort Elijah J. Davis
collection DOAJ
description ABSTRACT Sexual dimorphism is intriguing because it suggests that males and females differ in phenotypic optima for traits and that sex‐specific trait values can evolve despite a shared genome. Differences in sexual dimorphism across populations or species suggest that the nature of sexual selection and/or genetic constraints differ among species. Here, we measured sexual dimorphism in 20 species of North American killifish (Fundulidae) in size and shape of dorsal, anal, and caudal fins. We observed profound sexual dimorphism in anal and dorsal fin size and shape across all species, suggesting a common direction of selection. Sexual dimorphism was also present in caudal fin size and shape but was much lower in magnitude, with several species not differing from a null expectation of zero. There was little evidence for a phylogenetic signal in the levels of sexual dimorphism in dorsal and anal fin traits. We also found a strong phylogenetic correlation between sexual dimorphism in anal and dorsal fin shape but no phylogenetic correlation between fin area, base length, or ray length across different fins. Our results indicate that there is pronounced sexual dimorphism in anal and dorsal fin size and shape across fundulids. Similar patterns of sexual dimorphism in anal and dorsal fin properties have been documented in other groups, including gars, bichirs, graylings, minnows, and many species in the Atherinomorpha, suggesting that this pattern may be common across Actinopterygii.
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series Ecology and Evolution
spelling doaj-art-260fc53447ff4b0aaeb88f3c812129dd2025-08-20T03:26:55ZengWileyEcology and Evolution2045-77582025-04-01154n/an/a10.1002/ece3.71194Sexual Dimorphism in Fin Size and Shape in North American KillifishElijah J. Davis0Kasey Brockelsby1Milton Tan2Rebecca C. Fuller3Department of Evolution, Ecology, and Behavior, School of Integrative Biology University of Illinois Urbana Illinois USADepartment of Evolution, Ecology, and Behavior, School of Integrative Biology University of Illinois Urbana Illinois USAPrairie Research Institute, Illinois Natural History Survey University of Illinois Champaign Illinois USADepartment of Evolution, Ecology, and Behavior, School of Integrative Biology University of Illinois Urbana Illinois USAABSTRACT Sexual dimorphism is intriguing because it suggests that males and females differ in phenotypic optima for traits and that sex‐specific trait values can evolve despite a shared genome. Differences in sexual dimorphism across populations or species suggest that the nature of sexual selection and/or genetic constraints differ among species. Here, we measured sexual dimorphism in 20 species of North American killifish (Fundulidae) in size and shape of dorsal, anal, and caudal fins. We observed profound sexual dimorphism in anal and dorsal fin size and shape across all species, suggesting a common direction of selection. Sexual dimorphism was also present in caudal fin size and shape but was much lower in magnitude, with several species not differing from a null expectation of zero. There was little evidence for a phylogenetic signal in the levels of sexual dimorphism in dorsal and anal fin traits. We also found a strong phylogenetic correlation between sexual dimorphism in anal and dorsal fin shape but no phylogenetic correlation between fin area, base length, or ray length across different fins. Our results indicate that there is pronounced sexual dimorphism in anal and dorsal fin size and shape across fundulids. Similar patterns of sexual dimorphism in anal and dorsal fin properties have been documented in other groups, including gars, bichirs, graylings, minnows, and many species in the Atherinomorpha, suggesting that this pattern may be common across Actinopterygii.https://doi.org/10.1002/ece3.71194Cyprinodontiformesfin shapemedian finssexual dimorphismsexual selection
spellingShingle Elijah J. Davis
Kasey Brockelsby
Milton Tan
Rebecca C. Fuller
Sexual Dimorphism in Fin Size and Shape in North American Killifish
Ecology and Evolution
Cyprinodontiformes
fin shape
median fins
sexual dimorphism
sexual selection
title Sexual Dimorphism in Fin Size and Shape in North American Killifish
title_full Sexual Dimorphism in Fin Size and Shape in North American Killifish
title_fullStr Sexual Dimorphism in Fin Size and Shape in North American Killifish
title_full_unstemmed Sexual Dimorphism in Fin Size and Shape in North American Killifish
title_short Sexual Dimorphism in Fin Size and Shape in North American Killifish
title_sort sexual dimorphism in fin size and shape in north american killifish
topic Cyprinodontiformes
fin shape
median fins
sexual dimorphism
sexual selection
url https://doi.org/10.1002/ece3.71194
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AT rebeccacfuller sexualdimorphisminfinsizeandshapeinnorthamericankillifish