Mutants highlight the modular control of butterfly eyespot patterns

Authors

  • Antónia Monteiro,

    Corresponding author
    1. Section of Evolutionary Biology, Institute of Evolutionary and Ecological Sciences (EEW), Leiden University, P.O. Box 9516, 2300 RA Leiden, The Netherlands
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    • 1

      Present address: Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14260, USA.

  • Joop Prijs,

    1. Section of Evolutionary Biology, Institute of Evolutionary and Ecological Sciences (EEW), Leiden University, P.O. Box 9516, 2300 RA Leiden, The Netherlands
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  • Minka Bax,

    1. Section of Evolutionary Biology, Institute of Evolutionary and Ecological Sciences (EEW), Leiden University, P.O. Box 9516, 2300 RA Leiden, The Netherlands
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  • Thomas Hakkaart,

    1. Section of Evolutionary Biology, Institute of Evolutionary and Ecological Sciences (EEW), Leiden University, P.O. Box 9516, 2300 RA Leiden, The Netherlands
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  • Paul M. Brakefield

    1. Section of Evolutionary Biology, Institute of Evolutionary and Ecological Sciences (EEW), Leiden University, P.O. Box 9516, 2300 RA Leiden, The Netherlands
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*Author for correspondence (e-mail monteiro@buffalo.edu)

Abstract

SUMMARY The eyespots on butterfly wings are thought to be serially homologous pattern elements. Yet eyespots differ greatly in number, shape, color, and size, within and among species. To what extent do these serially homologues have separate developmental identities, upon which selection acts to create diversity? We examined x-ray–induced mutations for the eyespots of the nymphalid butterfly Bicyclus anynana that highlight the modular control of these serially homologous wing pattern elements. These mutations reduce or eliminate individual eyespots, or groups of eyespots, with no further effect on the wing color pattern. The collection of mutants highlights a greater potential developmental repertoire than that observed across the genus Bicyclus. We studied in detail one such mutation, of codominant effect, that causes the elimination of two adjacent eyespots on the ventral hindwing. By analyzing the expression of genes known to be involved in eyespot formation, we found an alteration in the differentiation of the “organizing” cells at the eyespot's center. No such cells differentiate in the wing subdivisions lacking the two eyespots in the mutants. We propose several developmental models, based on wing compartmentalization in Drosophila, that provide the first framework for thinking about the molecular evolution of butterfly wing pattern modularity.

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