|
|
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...
|
|
|
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
|
|
|
Fitness costs and benefits of sexual promiscuity in birds
Zdobinská, Helena ; Michálková, Romana (advisor) ; Sládeček, Martin (referee)
In more than 75 % bird species, extra-pair paternity (situation, when at least one extra-pair young in the nest is sired by other male than a social partner of female) has been found. While male interset in attending extra-apir copulations (EPC) seems to be intuitive (more offsring sired), female motivation to engage in EPC are much less clear and obvious. Therefore, many adaptive hypotheses have been proposed to explain female proscuity. Adaptive hypothese state, that female benefits from this behaviour (higher genetic quality of offspring). The empirical evidence for such benefits, however, are missing and adaptive hypotheses remain a controversial topic. This has led to the emergence of non-adaptive hypothesis, that assume that EPC can evolve as a by-product of selection on other trait and female may not benefit from this behaviour. However, non-adaptive hypotheses are often neglected. Aim of this bachelor thesis is to take into account benefits and costs for both sexes and to point out some of the limitations of studies on EPC. Key words: Extra-pair paternity, extra-pair copulations, promiscuity, adaptive hypothesis, nonadaptive hypothesis, sexual selection, limitation of studies
|
|
|
Evidence for direct and indirect benefits of female promiscuity in vertebrates
Kuba, Martin ; Albrecht, Tomáš (advisor) ; Šulc, Michal (referee)
Female promiscuous behaviour has been observed in many vertebrate groups but its evolution and potential benefits to promiscuous females remain unclear. To explain female promiscuous behaviour, both adaptive and non-adaptive hypotheses have been proposed. According to adaptive hypotheses, females are promiscuous, because they gain benefits through multiple male copulations. These can further be divided into direct benefits hypotheses, where females are assumed to benefit directly from promiscuity by gaining more resources to themselves and improving their own survival, and indirect (genetic) benefits hypotheses where fitness gains to promiscuous females are through improved quality of their offspring. In contrast, according to non-adaptive hypotheses, females do not gain any benefits from promiscuous behaviour and female promiscuous behaviour is a result of male offensive strategies to gain paternity. Adaptive hypotheses, especially those concerning genetic benefits, are highly debated and existing studies often differ in their conclusions. The aim of this thesis is to provide a review of studies evaluating adaptive and non-adaptive hypotheses to explain female promiscuous behaviour in vertebrates. Key words: Promiscuity, sexual conflict, sperm competition, good genes, genetic complementarity,...
|
|
|
Alternative reproductive strategies and sexual selection in barn swallow Hirundo rustica
Michálková, Romana ; Albrecht, Tomáš (advisor) ; Sedláček, Ondřej (referee) ; Svobodová, Jana (referee)
Molecular techniques have revealed that avian mating system is more diverse and complex than previously thought. Both males and females can use alternative reproductive tactics to increase their fitness. Here, we have determined the prevalence of conspecific brood parasitism (CBP, 22% of nests), quasi-parasitism (QP, 6.5% of nests) and extra-pair paternity (EPP, 51.2% of nests) in European subspecies of barn swallow (Hirundo rustica rustica). In contrast to EPP and CBP, QP is rare and has been described in only a few bird species. Our data indicate nonrandom QP patterns, suggesting that this tactic can be considered a third alternative reproductive strategy, alongside CBP and EPP. Sexual ornaments are usually assumed to evolve as condition-dependent signals of individual quality. In this context, a positive correlation between the expression of ornamental traits and survival, is expected. Evolutionary theory predicts that females seek extra-pair fertilizations from high-quality (more ornamented) males and EPP has consequently been proposed as a principal protagonist in the evolution of male secondary sexual traits, however empirical evidence in support of the assertion is relatively scarce. Despite decades of research into the role of EPP in sexual selection, the potential fitness advantages for...
|
|
|
Fitness costs and benefits of sexual promiscuity in birds
Zdobinská, Helena ; Michálková, Romana (advisor) ; Sládeček, Martin (referee)
In more than 75 % bird species, extra-pair paternity (situation, when at least one extra-pair young in the nest is sired by other male than a social partner of female) has been found. While male interset in attending extra-apir copulations (EPC) seems to be intuitive (more offsring sired), female motivation to engage in EPC are much less clear and obvious. Therefore, many adaptive hypotheses have been proposed to explain female proscuity. Adaptive hypothese state, that female benefits from this behaviour (higher genetic quality of offspring). The empirical evidence for such benefits, however, are missing and adaptive hypotheses remain a controversial topic. This has led to the emergence of non-adaptive hypothesis, that assume that EPC can evolve as a by-product of selection on other trait and female may not benefit from this behaviour. However, non-adaptive hypotheses are often neglected. Aim of this bachelor thesis is to take into account benefits and costs for both sexes and to point out some of the limitations of studies on EPC. Key words: Extra-pair paternity, extra-pair copulations, promiscuity, adaptive hypothesis, nonadaptive hypothesis, sexual selection, limitation of studies
|
|
|
Extrapair paternity and adaptive explanations of female promiscuity in birds
Siegelmannová, Nikola ; Albrecht, Tomáš (advisor) ; Poláková, Radka (referee)
Extra-pair paternity are commonly detected in populations of social monogamous birds, however it remains unclear how this strategy evolves and is maintained. Several adaptive and non-adaptive explanations were, proposed to explain female promiscuity with major attention being devoted to the hypothesis of genetic benefits to females in form of good or compatible genes for their offspring. These theories assume that extra-pair offspring are of better quality than their maternal half-sibs in the nest. This thesis summarizes available studies that have compared benefits and costs for males and females from extra-paired paternity and evaluated the adaptive explanation of female promiscuity. It seems that the evidence for inderect benefits to female promiscuity are generally week in birds, and other mechanisms, such as sexual conflict or genetic correlations between the sexes may play a role in explaining the female bird propensity to copulate with extra-pair mates. Powered by TCPDF (www.tcpdf.org)
|
|
|
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
|
guest ::
