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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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The association between tail streamer length and male atractiveness in barn swallows
Záleská, Josefína ; Albrecht, Tomáš (advisor) ; Cepák, Jaroslav (referee)
In the view of the sexual selection research, the barn swallow (Hirundo rustica), and its European subspecies (Hirundo rustica rustica) in particular, belongs to the most detailed studied bird species all over. The males of the European subspecies have in general markedly longer outer tail streamers than the females have and, based on research in several European populations, this tail ornamental trait plays an important role in sexual selection in this subspecies. The length of the tail streamers was found to be related to several main parameters that are connected to individual attractiveness in socially monogamous pairing systems, such as early partner acquisition and earlier nesting initiation date, the probability of repeated nestings in a breeding season or the number of successfully raised young. The main aim of the presented diploma theses is to assess to what extend is the length of the tail streamers a determinative trait related to male attractiveness in a South Bohemian population of the European barn swallow. The results of this thesis imply that the tail streamer length of males is, indeed, an attractive trait in this population, connected to multiple mating advantages. KEY WORDS Sexual dimorphism, sexual selection, barn swallow, nesting initiation, attractivity, reproductive success,...
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Morphological, behavioural and physiological adaptations of island-dwelling birds
Krpcová, Alena ; Albrecht, Tomáš (advisor) ; Mikula, Ondřej (referee)
Morphological, behavioural and physiological adaptations of island-dwelling birds Alena Krpcová prof. Tomáš Albrecht, Ph.D. Abstract Islands represent a model system of evolutionary biology. They are isolated environments in which specific ecological conditions often operate differently than on the mainland. In this context, island taxa develop unique morphological, physiological and behavioural adaptations, collectively referred to as island syndromes, through convergent evolution. This thesis aims to provide an overview of selected island syndromes that have been detected in a large group of vertebrates typically inhabiting islands, the birds (Aves). Attention is paid to body size, wing length and associated flightlessness, as well as changes in life strategies (life span, offspring care, clutch size and egg size), antipredatory behaviour and island tameness, and finally the relationship between the above-mentioned island syndromes and the extinction of island species caused by humans and the invasive organisms that accompany them. Factors operating in island environments that may influence the evolution of selected island syndromes are discussed, and it is suggested that reduced predation pressure on islands and an energetic trade-offs between investments in survival, defence and reproduction could be...
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Sperm competition in birds and causes for its intra- and iterspecific variation
Šplíchalová, Petra ; Albrecht, Tomáš (advisor) ; Poláková, Radka (referee)
This bachelor thesis focuses on describing the occurrence and within- and between species variation of extra-pair paternity (EPP) in socially monogamous birds. In the first part of thesis I discribe variation in EPP levels among birds - I identify species with no EPP ever recorded, and species with extreme values of EPP. Extra-pair paternity seems to be more common in passerines than non-passerines. In the second part of my thesis, the most influential correlates of EPP levels in passerine birds are discussed. I summarize contemporary knowledge of the effect of these (mostly ecological) factors on EPP. These include breeding density and synchrony, population genetic diversity, adult mortality and longevity and male contribution to parental care. Key words: promiscuity, extar-pair paternity, extra-pair copulations, sperm competition
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Flight initiation distances and life histories in birds: comparison of intra- and interspecific approaches
Brzobohatá, Tereza ; Albrecht, Tomáš (advisor) ; Klvaňa, Petr (referee)
Information about the distance, in which the birds flee from predators, may help us to better understand avian escape behavior and stress responses. These distances are influenced by many life-history traits and related factors, both on intraspecific and interspecific levels. This bachelor's thesis is trying to summarize the current knowledge of agents influencing flight initiation distances (FID) of birds, in the form of a literary research. The first section deals with antipredator behavior in birds, and explains methods that are used for measuring critical distances. In the second part of thesis, factors affecting flight initiation distances on intraspecific level are described. The main emphasis is on impact of age characteristics, body sizes, reproductive investments and geographical distribution. The last chapter summarizes the information about relationships between FID and life-history traits on interspecific level. The age of the individual, levels of stress hormones, the effect of the season and biotop are described in detail. Powered by TCPDF (www.tcpdf.org)
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Condition dependence of secondary ornamentation and mate choice in Grey Partridges
Gabrielová, Barbora ; Albrecht, Tomáš (advisor) ; Sedláček, Ondřej (referee)
This study focuses on relationships between individual condition, measures of ornament expression and mate choice in the Grey Partridge (Perdix perdix). It is based on the correlative data as well as results of manipulative experiments. I found positive correlation between the size of melanin- and carotenoid-based ornaments in partridges. The size and the redness of the carotenoid skin patch, and the size of the melanin-based feather ornamentation were associated with several measures of immunity and overall body condition (complement activity, ratio of immature erythrocytes, heterophil/leucocyte ratio, response to novel antigen). Furthermore, data from natural populations indicate that the expression of carotenoid-based ornamentation is associated with sexual attractiveness (measured as the ability to obtain a social mate) in partridges. Data from captive individuals indicate that carotenoid supplementation improves the redness of carotenoid-based ornament, while the stimulation of the immune system under increasing concentrations of supplemented carotenoids has no measurable effect on condition and physiological state. This seems to contradict predictions of the 'Carotenoid maintenance hypothesis'. Overall, results better understanding the role of carotenoid and melanin-based ornamentation in signaling...
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