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Sexual promiscuity, cryptic female choice and the biology of passerine sperm
Míčková, Kristýna ; Albrecht, Tomáš (advisor) ; Vrbacký, Marek (referee) ; Krist, Miloš (referee)
The discovery of postcopulatory mechanisms of mate choice has fundamentally altered our understanding of sexual selection. Passerines are an ideal group for studying two basic mechanisms of postcopulatory sexual selection, sperm competition and cryptic female choice. This doctoral thesis focuses on postcopulatory sexual selection in passerines from three different angles. In this study, we investigated (1) age-related changes in traits that can affect male reproductive success (sperm morphology, velocity and production) and a trade-off between these traits and lifespan in male barn swallows (Hirundo rustica); (2) variation in seminal fluid and sperm proteins in six selected passerine species and whether these differences are caused by phylogeny or postcopulatory sexual selection; and (3) the protein composition of female barn swallow cloacal fluids in four phases of the reproductive season, changes in protein composition in individual phases, and identification of phase-specific proteins. Our results show that there is no unified trend for changes in sperm traits or sperm production across male lifespan. While sperm morphology and velocity do not change considerably, sperm production increases in first years of life. However, excessive investment in sperm production could reduce the male's chances...
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Sperm and ejaculate traits and their association with male fertilization success in vertebrates with internal and external fertilization
Nesvedová, Anna ; Albrecht, Tomáš (advisor) ; Svobodová, Jana (referee)
Postcopulatory sexual selection, which encompasses sperm competition and cryptic female choice, has long been an understudied or neglected component of sexual selection. However, in sexually promiscuous organisms, it can play a crucial role in mate choice. Sperm competition exerts strong selective pressure on sperm phenotypes, yet detailed intraspecific studies investigating the relationship between sperm phenotype and male fertilization success remain relatively scarce. Furthermore, selection may operate differently in organisms with external fertilization (where the female's role in influencing sperm competition outcomes is limited) versus internal fertilization (where sperm competition occurs within the female reproductive tract, and cryptic female choice can also come into play), potentially favoring different sperm characteristics. This thesis, based on research synthesis, summarizes the knowledge about sperm traits that influence male fertilization success in promiscuous organisms, with a focus on differences in sperm trait selection in organisms with internal and external fertilization. To elucidate this issue, the thesis first provides a brief overview of the morphological diversity of vertebrate sperm. It explores sperm morphology and its relationship with male fertilization success, as...
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Roles of sperm morphology variation on proteomic content in muroid rodents
Drozdová, Tereza ; Stopka, Pavel (advisor) ; Postlerová, Pavla (referee)
We can find a whole range of morphological differences between the spermatozoa of different animal species, whether at the level of shape, size or intracellular arrangement. It has been proven that these differences are likely to be driven by selective pressure caused by sperm competition. This can cause morphological adaptations that give sperm a selective advantage and increase the individual's success in fertilization. The main goal of my diploma thesis was to determine whether individual morphological variability of spermatozoa is detectable at the proteome level and possibly to determine what changes at the proteome level occur in spermatozoa with changing morphology. Three species of rodents, Mus musculus, Apodemus flavicollis and Microtus arvalis, were selected for this study, and a thorough morphometric measurement of their sperm was performed. Because the greatest variation was detected in the dimensions of the apical hook, only acrosomal proteins were analyzed by mass spectrometry, and then the proteins that distinguished the most sperm with long and short apical hooks were determined by discriminant analysis and machine learning methods. A significant trend among sperm-separating proteins with short and long apical hooks, regardless of species, has been identified for proteins involved...
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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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Postcopulatory sexual selection on phenotypic traits in European barn swallows
Míčková, Kristýna ; Albrecht, Tomáš (advisor) ; Svobodová, Jana (referee)
Sperm phenotype is an essential indicator of the male ejaculate quality and may have a significant impact on male reproductive success. Sperm phenotypes are considerably variable across species but variation is also found among males within species. This thesis examines (1) variation in sperm phenotypes among males in barn swallows (Hirundo rustica), (2) changes in male ejaculate quality with age, (3) relationships between sperm morphology and motility, (4) effects of sperm phenotypes (morphology and motility) on male fertilization success, using a large dataset of 174 observation for 130 males, and (5) the influence of female reproductive environment on sperm motility. From the tested variables, only midpiece length correlated with male age. Older males had shorter midpiece but no relationship between male age and reproductive success was found. Sperm length negatively affected sperm motility and, simultaneosly, relative midpiece length posively correlated with sperm motility. No correlation was found between the male reproductive success and sperm motility, presence of abnormalities, length of outermost tail feathers or age. Males with shorter relative midpiece were more successful in within-pair paternity, and males with shorter sperms but longer relative midpiece were more successful in...
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