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Sperm morphology and motility in estrildid finches of the genus Lonchura
Šárová, Markéta ; Reifová, Radka (advisor) ; Frolíková, Michaela (referee)
Sexual selection plays an important role in the evolution of animals. Today we already know that it takes place not only before copulation (precopulatory sexual selection), but also after copulation. This type of sexual selection is called postcopulatory sexual selection, and occurs mainly in promiscuous species, where females mate with multiple males. In this case, sperm competition occurs in the female reproductive tract. To increase the likelihood of their reproductive success, males began to develop surprisingly diverse sperm adaptations at the morphological, physiological, or behavioural levels. These adaptations often affect sperm velocity (motility), which is a key factor for successful egg fertilization. However, the result of reproductive success can also be influenced by females, who may prefer sperm with a certain phenotype in the process of cryptic female choice, and thus, for example, obtain better genes for offspring. In some species, females even can have the ability to sort and store sperm in specialized organs in which the sperms are nourished for some time, and then used to fertilize the egg. Even in this case, the storage of sperm is often affected by sperm morphology. Due to these mechanisms of postcopulatory sexual selection, sperm are under strong selection pressure, which can...
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Post-copulatory sexual selection and sperm phenotypes
Bílková, Karolína ; Albrecht, Tomáš (advisor) ; Děd, Lukáš (referee)
Postcopulatory sexual selection has two basic components, sperm competition and cryptic female choice. In this thesis I summarize available data of the influence of postcopulatory sexual selection on sperm morhology and phenotype, focusing on both vertebrates and selected invertebrate taxa. In the first part of my thesis, I provide an overview of sperm phenotype adaptations that are influenced by the sperm competition and may closely determine male fertilization success. These are the length of sperm, sperm swimming speed and motility, longevity of sperm and the amount of ejaculate produced. Sperm phenotypes that evolve under strong postocopulatory selection may also involve morphological adaptations alowing sperm to mutually cooperate in the female reproductive tract. The cryptic female choise, in which female selectively use sperm after the sperm enters her reproductive tract, and the coevolution of sperm morphology and female reproductive tract is presented in the second part of this thesis. Powered by TCPDF (www.tcpdf.org)
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