RUNAWAY SEXUAL SELECTION LEADS TO GOOD GENES

Authors

  • Christopher H. Chandler,

    1. BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, Michigan 48824
    2. Department of Zoology, Michigan State University, East Lansing, Michigan 48824
    3. Present address: Department of Biological Sciences, SUNY Oswego, Oswego, New York 13126
    4. E-mail: christopher.chandler@oswego.edu
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  • Charles Ofria,

    1. BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, Michigan 48824
    2. Department of Computer Science and Engineering, Michigan State University, East Lansing, Michigan 48824
    3. Program in Ecology, Evolutionary Biology, and Behavior, Michigan State University, East Lansing, Michigan 48824
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  • Ian Dworkin

    1. BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, Michigan 48824
    2. Department of Zoology, Michigan State University, East Lansing, Michigan 48824
    3. Program in Ecology, Evolutionary Biology, and Behavior, Michigan State University, East Lansing, Michigan 48824
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Abstract

Mate choice and sexual displays are widespread in nature, but their evolutionary benefits remain controversial. Theory predicts these traits can be favored by runaway sexual selection, in which preference and display reinforce one another due to genetic correlation; or by good genes benefits, in which mate choice is advantageous because extreme displays indicate a well-adapted genotype. However, these hypotheses are not mutually exclusive, and the adaptive benefits underlying mate choice can themselves evolve. In particular, examining how and why sexual displays become indicators of good genes is challenging in natural systems. Here, we use experimental evolution in “digital organisms” to demonstrate the origins of condition-dependent indicator displays following their spread due to a runaway process. Surprisingly, handicap-like costs are not necessary for displays to become indicators of male viability. Instead, a pleiotropic genetic architecture underlies both displays and viability. Runaway sexual selection and good genes benefits should thus be viewed as interacting mechanisms that reinforce one another.

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