A large variation in spermatophore size exists among bush-crickets; traditionally this is attributed to environmental and physiological differences. However, interspecific size variation may also be due to behaviour or common ancestry.... more
A large variation in spermatophore size exists among bush-crickets; traditionally this is attributed to environmental and physiological differences. However, interspecific size variation may also be due to behaviour or common ancestry. Few studies have documented the evolutionary ecology of spermatophore size variation while accounting for environmental variation and relatedness. Controlling for body mass, common ancestry, and diet, my thesis is a study of the variations in spermatophore size of the genus Poecilimon. I investigate aspects of operational sex ratio, reproductive effort, mating effort, paternal investment, ejaculate protection, sperm competition, mate choice, sexual conflict and reproductive fitness. I gathered previously unpublished data and extracted data from the literature to make comparative analyses among 33 Poecilimon taxa. For specific focal comparisons, I further intensively studied five taxa in the field that vary markedly in spermatophore size. First, I obse...
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Abstract During mating, male bush-crickets transfer a costly nuptial gift to the female to consume while the ejaculate is transferred into her. The nuptial gift functions primarily as ejaculate protection, although in some larger... more
Abstract During mating, male bush-crickets transfer a costly nuptial gift to the female to consume while the ejaculate is transferred into her. The nuptial gift functions primarily as ejaculate protection, although in some larger spermatophore-producing species the gift functions additionally as paternal investment. While costly, production of large spermatophores may increase male fitness by providing a way in which males outcompete conspecific male sperm competition and female control over mating. For females, the nuptial gift may provide nutrients that increase her fecundity or allow greater fitness; however, larger gifts may also reduce a female’s mating optima. A large variation in spermatophore size exists among bush-crickets; traditionally this is attributed to environmental and physiological differences. However, interspecific size variation may also be due to behaviour or common ancestry. Few studies have documented the evolutionary ecology of spermatophore size variation w...
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During mating, male bush-crickets transfer a complex spermatophore to the female. The spermatophore is comprised of a large nuptial gift which the female consumes while the sperm from the ejaculate-containing ampulla are transferred into... more
During mating, male bush-crickets transfer a complex spermatophore to the female. The spermatophore is comprised of a large nuptial gift which the female consumes while the sperm from the ejaculate-containing ampulla are transferred into her. Two main functions of the nuptial gift have been proposed; the ejaculate protection hypothesis has evolved in a sexual selection context and predicts that the time to consume the gift is no longer than necessary to allow for full ejaculate transfer. The parental investment hypothesis maintains that gift nutrients increase the fitness or quantity of offspring and hence the gift is likely to be larger than is necessary for complete sperm transfer. With an aim to better understanding the primary function of nuptial gifts, we examine sperm transfer data from field populations of five Poecilimon bush-cricket taxa with varying spermatophore sizes. In the species with the largest spermatophore, the gift was four times larger than necessary to allow fo...
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During mating, male insects of certain species transfer a costly nuptial gift, a large spermatophore, which is eaten by the female as sperm transfer into her. The spermatophore components (the sperm-free spermatophylax and the sperm... more
During mating, male insects of certain species transfer a costly nuptial gift, a large spermatophore, which is eaten by the female as sperm transfer into her. The spermatophore components (the sperm-free spermatophylax and the sperm ampulla) vary greatly in size between species, and have a direct influence on male fitness. Studies of the relationship between spermatophore size variation and male