A supergene-linked estrogen receptor drives alternative phenotypes in a polymorphic songbird Open Access

Abstract

Behavioral evolution relies on genetic changes, yet few behaviors can be traced to specific genetic sequences in vertebrates. Here, we show experimental evidence that differentiation of a single gene has contributed to the evolution of divergent behavioral phenotypes in the white-throated sparrow, a common backyard songbird. In this species, a series of chromosomal inversions has formed a supergene that segregates with an aggressive phenotype. The supergene has captured ESR1, the gene that encodes estrogen receptor alpha (ER-alpha); as a result, this gene is accumulating changes that now distinguish the supergene allele from the standard allele. Our results show that in birds of the more aggressive phenotype, ER-alpha knockdown caused a phenotypic change to that of the less aggressive phenotype. Next, we showed that in a free-living population, aggression is predicted by allelic imbalance favoring the supergene allele. Finally, we identified cis-regulatory features, both genetic and epigenetic, that explain the allelic imbalance. This work provides a rare illustration of how genotypic divergence has led to behavioral phenotypic divergence in a vertebrate.

Table of Contents

Acknowledgments                                                                                                    vii

Table of Contents                                                                                                     ix

List of Tables                                                                                                            x

List of Figures                                                                                                           xi

List of Symbols and Abbreviations                                                                       xii

Introduction                                                                                                              1

Methods                                                                                                                     5

Results                                                                                                                       10

Discussion                                                                                                                 20

References                                                                                                                 24

Appendix                                                                                                                   36

About this Dissertation

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School	Laney Graduate School
Department	Psychology
Subfield / Discipline	Neuroscience and Animal Behavior
Degree	Ph.D.
Submission	Dissertation
Language	English
Research Field	Biology, Neuroscience Biology, Endocrinology Biology, Evolution and Development
Keyword	chromosomal inversion social behavior songbird
Committee Chair / Thesis Advisor	Donna Maney, Emory University
Committee Members	Eric Ortlund, Emory University Soojin Yi, Georgia Institute of Technology Kim Wallen, Emory University Patricia Brennan, Emory University

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