The evolution of male genitalia: patterns of genetic variation and covariation in the genital sclerites of the dung bettle Onthophagus taurus

C.M. House, Leigh Simmons

    Research output: Contribution to journalArticle

    50 Citations (Scopus)

    Abstract

    Three main hypotheses, have been invoked to explain divergent genital evolution, the lock and key, pleiotropy, and sexual selection hypotheses, each of which make different predictions about how genital traits are inherited. Here we used a half-sib breeding design to examine the patterns of genetic variation and covariation between male genital sclerites, and their covariance with general body morphology in the dung beetle Onthophagus taurus. We found CVA's and CVP's were similar for both genital and general morphological traits and that CVR's were large for both trait types. We found that male genital sclerites were negatively genetically correlated with general morphological traits. Variation in male genital morphology has direct implications for a male's fertilization success and the resulting sexual selection acting on male genitalia is predicted to maintain high levels of additive genetic variance. Contrary to this prediction, we found that individual genital sclerites all had low levels of additive genetic variance and large maternal and environmental sources of variation. Our data suggest that the genital sclerites in O. taurus are not inherited independently but as a genetically integrated unit. More importantly, the way the different sclerites function to influence male fertilization success reflects this genetic integration. Even though levels of V-A in individual genital sclerites may be low, there may still be sufficient V-A in multivariate trait space for selection to generate evolutionary change in the overall morphology of male genitalia.
    Original languageEnglish
    Pages (from-to)1281-1292
    JournalJournal of Evolutionary Biology
    Volume18
    Issue number5
    DOIs
    Publication statusPublished - 2005

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