Sperm competition and the Anuran seminal vesicles

Sharron Perks

    Research output: ThesisDoctoral Thesis

    267 Downloads (Pure)

    Abstract

    [Truncated abstract] after the first review of sperm competition in anurans, our knowledge of sperm competition in frogs still lags behind other taxa. This is particularly true of the influence of sperm competition in shaping the evolution of male ejaculate traits. While studies in many vertebrate and invertebrate groups have produced substantial evidence that both sperm and non-sperm components of the ejaculate have responded to sperm competition pressures, studies in frogs have been restricted to a comparatively small number of investigations relating only to the sperm component of the ejaculate. This thesis focuses on the accessory sex glands of frogs (the seminal vesicles) that store sperm and produce the seminal fluid components. I examine an old, neglected literature, compare modifications of the reproductive tract across species and experimentally analyse seminal fluid function in an anuran. Many anurans have modifications of the reproductive tract that vary greatly in size and form, but which can all be considered seminal vesicles (Chapter 1). The relative size of the seminal vesicles was associated with relative testes sizes in analyses at two levels: a broad-scale study across families (Chapter 2) and within the foam-nesting rhacophorids (Chapter 3). In contrast, there was no influence of clutch size, egg size or oviposition site on the size of the seminal vesicle (Chapter 2). Collectively, these data suggest a high degree of sperm competition favours the evolution of larger seminal vesicles, as expected from current sexual selection theory and comparative analyses in other animals. Multiple paternity was also detected in single-mother egg clutches of a species with a large seminal vesicle, further supporting this conclusion (Chapter 4)...
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2011

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