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Diversity and evolution of amphibian pupil shapes

Thomas, K. N., Rich, C., Quock, R. C. , Streicher, J. W., Gower, D. J., Schott, R. K., Fujita, M. K., Douglas, R. H. ORCID: 0000-0002-6862-2768 & Bell, R. C. (2022). Diversity and evolution of amphibian pupil shapes. Biological Journal of the Linnean Society, 137(3), pp. 434-449. doi: 10.1093/biolinnean/blac095


Pupil constriction has important functional consequences for animal vision, yet the evolutionary mechanisms underlying diverse pupil sizes and shapes are poorly understood. We aimed to quantify the diversity and evolution of pupil shapes among amphibians and to test for potential correlations to ecology based on functional hypotheses. Using photographs, we surveyed pupil shape across adults of 1294 amphibian species, 74 families and three orders, and additionally for larval stages for all families of frogs and salamanders with a biphasic ontogeny. For amphibians with a biphasic life history, pupil shape changed in many species that occupy distinct habitats before and after metamorphosis. In addition, non-elongated (circular or diamond) constricted pupils were associated with species inhabiting aquatic or underground environments, and elongated pupils (with vertical or horizontal long axes) were more common in species with larger absolute eye sizes. We propose that amphibians provide a valuable group within which to explore the anatomical, physiological, optical and ecological mechanisms underlying the evolution of pupil shape.

Publication Type: Article
Additional Information: © The Author(s) 2022. Published by Oxford University Press on behalf of The Biological Journal of the Linnean Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Publisher Keywords: activity period, Anura, aquatic, Caudata, fossorial, Gymnophiona, optics, scansorial, vision
Subjects: Q Science > QH Natural history > QH301 Biology
R Medicine > RE Ophthalmology
Departments: School of Health & Psychological Sciences > Optometry & Visual Sciences
Text - Published Version
Available under License Creative Commons Attribution.

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