Sexual Conflict

by

Claudia Fricke

• LAST REVIEWED: 13 January 2014
• LAST MODIFIED: 13 January 2014
• DOI: 10.1093/obo/9780199941728-0022

Introduction

Sexual conflict is an evolutionary theory within the framework of sexual selection based on the observation that a trait that is beneficial for the reproductive success of one sex can reduce the fitness of the other sex. This new theory changed our interpretation of male-female interactions. Historically, reproduction was seen as an act of complete cooperation; the idea of sexual conflict instead highlights that cooperation is just one extreme along a gradient that can range from mostly cooperation to mostly conflict between the sexes. Sexual conflict can occur when the evolutionary interests of the two sexes are not in accord, resulting in opposing selection pressures on males and females. These conditions are met as males and females differ in their investment in reproduction, and this leads to distinct roles with different fitness optima for each sex. Both optima cannot be reached simultaneously, resulting in direct selection on each sex to maximize its fitness at the expense of moving the other sex further off its optimum. This perpetual tug-of-war between the sexes causes novel opportunities for male-female coevolution, which is predicted to result in rapid evolution of sexual traits that can ultimately lead to diversification and contribute to reproductive isolation and hence speciation.

General Overviews

Sexual conflict is a relatively recent theory formulated at the beginning of the 1970s. Andersson 1994, a classic monograph on sexual selection, only mentions sexual conflict sporadically, and it is not represented in detail as an independent alternative theory to the “classical” sexual selection theories. A comprehensive monograph dedicated to the topic of sexual conflict is Arnqvist and Rowe 2005; it is a good introduction to the topic and discusses the younger theory alongside “classical” sexual selection theories, thus providing a very good general overview. A shorter review focusing on how to detect sexual conflict is presented in Chapman, et al. 2003. More recent discussions of the topic can be found in dedicated special issues in three different journals. Volume 165(5) of the American Naturalist 2005 contains a supplement extending the discussions started during two symposia on the general importance of sexual conflict as an evolutionary force. Chapman, et al. 2006 collates the contributions to a discussion meeting on “Sexual conflict: a new paradigm?” The third is the 2009 volume 5(5) of the journal Biology Letters, presenting diverse articles on the topic “Sexual conflict and sex allocation.”

• Andersson, Malte B. 1994. Sexual selection. Princeton, NJ: Princeton Univ. Press.

  This is the standard book on sexual selection and is a comprehensive review of the field, but as sexual conflict was just slowly gaining attention when the book was written, sexual conflict theory is only mentioned in brief.

• Arnqvist, Göran, and Locke Rowe. 2005. Sexual conflict. Princeton, NJ: Princeton Univ. Press.

  This book is rich in examples and represents the broad range of taxa and traits shaped by sexual conflict. This book is a good starting point to gain a first understanding of the extent of sexual conflict.

• Chapman, Tracey, ed. 2009. Biology Letters 5.5.

  This issue contains several short review articles discussing different aspects of sexual conflict theory focusing on sex allocation.

• Chapman, Tracey, Göran Arnqvist, Jenny Bangham, and Locke Rowe. 2003. Sexual conflict. Trends in Ecology and Evolution 18:41–47.

  DOI: 10.1016/S0169-5347(02)00004-6

  This is a very readable short introduction to sexual conflict theory with a particular focus on different approaches to detecting sexual conflict and their advantages as well as pitfalls.

• Chapman, Tracey, Tom Tregenza and Nina Wedell, eds. 2006. Special Issue: Sexual conflict: A new paradigm? Philosophical Transaction of the Royal Society London B 361.1466.

  This is a special issue dedicated to review and discussion articles on diverse topics within the field of sexual conflict theory. It gives a good overview and some in-depth thoughts on different aspects of sexual conflict theory and developments.

• Hosken, David, and Rhonda Snook, eds. 2005. Special issue: How important is sexual conflict? American Naturalist 165.5 (Suppl.).

  Diverse contributions are collated with a focus on generating a measurable hypothesis to estimate the general importance of sexual conflict as a selection pressure shaping evolutionary change. Contributions are a mix of empirical data and models.