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Intensity of biparental care in Columbiformes and other selected bird taxa: a summary of the main ultimate and proximate mechanisms
Kopejtková, Lucie ; Landová, Eva (advisor) ; Tomášek, Oldřich (referee)
Order Columbiformes is not very numerous group of birds but their importance for recent science and for people in general in significant. They are one of the most studied group of birds and knowledge we now have of parental care and proximal mechanisms of its onset was obtained from this avian order. The main factors related to the development of intensive parental care, biparental care and cooperation between partners in parental care will first be discussed in individual chapters. The main evolutionary constraints and the main conflicts both between the sexes and parent-offspring conflict, which are closely related to the evolution of parental care, will be mentioned. The specific position of Columbiformes from the point of view of ultimate mechanisms will be mentioned. Further chapters should be devoted to the most important proximate mechanisms influencing parental care in Columbiformes. Keywords: Biparental care, Columbiformes, cooperation in parental care, parental conflict, parent-offspring conflict, prolactin
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Sperm competition in humans
Vydarená, Eliška ; Havlíček, Jan (advisor) ; Tomášek, Oldřich (referee)
Sperm competition has been observed and studied many times in a lots of animal species. It is currently also being considered in humans. Despite the number of studies, most of them were mainly focused on insects and birds. So far, only a small number of studies have dealt with sperm competition research in humans. For this reason, the question if sperm competition appeared and had selection pressure for the creation of various adaptations even in human evolution remains a controversial topic. In this bachelor thesis, I summarize the current knowledge of sperm competition in humans, the frequency of extra-pair copulation and paternity, and in individual chapters to indicate what adaptations to sperm competition may have developed in humans during their development. Key words Sperm competition, human sexuality, sperm, reproductive strategies
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Lipid composition of biological membranes and life-histories in songbirds
Šimonová, Kateřina ; Tomášek, Oldřich (advisor) ; Sam, Kateřina (referee)
Differences in the composition of cell membranes are considered to be the physiological mechanism responsible for different metabolic rates, life span and consequently, different life-histories. The membrane pacemaker theory suggests that higher membrane unsaturation may be an important factor responsible for higher metabolic rate and shorter life span of organisms. The alternative hypothesis, on the other hand, assumes that membranes can function as structural antioxidants, and thus that higher membrane unsaturation may be associated with longer life span. The aim of this work was to test how changes in the fatty acid composition of membranes depends on body size, latitude and altitude, within which different life-histories and metabolic rate were observed. Temperate and tropical lowland songbird species were chosen for the models testing the effect of latitude, and only tropical species of songbirds were chosen for the models testing the effect of altitude. Part of the work was molecular sex determination. Using gas chromatography and mass spectrometry, the amount of individual fatty acids contained in red blood cell phospholipids was obtained from blood samples. The results showed that the composition of the membranes in most cases correlates with body size, which also correlates with almost all...
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Oxidative stress and condition-dependence of ornamental signals of quality in socially monogamous songbird
Valášek, Stanislav ; Tomášek, Oldřich (advisor) ; Sedláček, Ondřej (referee)
6 ABSTRACT Conditional ornaments plays irreplaceable role in sexual selection in non-small part of by sexual reproduction reproducing animals. Fastidiousness of generating and later also carrying of these ornaments which show condition of their wearer, burdens also metabolism in non-small scale. This thesis tests hypothesis of mutual addiction between conditional ornaments, as the indicators of qualities of individuals and metabolism, as the most significant source of free radicals which are responsible for oxidative stress. The real weight of influence of ornament fastidiousness on organism, resp. on redox state, is tested in this thesis. Manipulations which were performed with individual males of model species should point how much the selected factors correlate each other. The barn swallow (Hirundo rustica) is the model species. Analyses of dates collected during trapping which were realized in breeding seasons in 2012 and 2013 does not show any important trends between observing variables. This fact is confirmed by minimal differences and inconsistent variability of levels of measured antioxidants - oxidoreductases, superoxide dismutase and glutathione peroxidase. The marginal effect of manipulations with one of the conditional ornaments which are presented in model species supports the hypothesis of...
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Physiological and hormonal mechanisms influencing ejaculate quality in birds
Mojžišová, Kateřina ; Tomášek, Oldřich (advisor) ; Svobodová, Jana (referee)
Sexual selection is an important mechanism of evolution. In addition to precopulatory sexual selection, arising when males compete for female partners, there is also postcopulatory sexual selection (sperm competition), when females copulate with more males. Even though most avian species are socially monogamous, most of them are also partially promiscuous. In such species, sperm competition is an important factor increasing variability in reproductive success between males. Male's success in sperm competition is primarily determined by sperm concentration, total sperm count and morphology and motility of spermatozoa. My bachelor thesis summarizes knowledge about the hormonal a physiological mechanisms that influence semen quality. This is especially the effect of sex and other hormones, physiological and oxidative stress, environmental conditions, antioxidant mechanism and composition of sperm cell membrane. Besides evaluating their influence on ejaculate quality on intraspecific level, I also describe their differences between avian species with respect to the differences of sperm competition.
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Reproductive senescence in female barn swallows (Hirundo rustica): age-related changes in components of reproductive success
Pazdera, Lukáš ; Tomášek, Oldřich (advisor) ; Riegert, Jan (referee)
The effect of age on an individual's fitness is one of the key topics of evolution ecology. Currently intensively studied manifestation of age is an aging of organism, thus a deterioration of metabolic functions and condition with age. An increasing count of studies shows that aging in the wild is rather a rule than exception, even with short-lived species of which the aging has not been previously presumed at all. Despite an increasing interest of evolution ecologists in this matter, some important aspects remain overlooked. Senescence of the traits are usually studied separately, therefore, an information whether an individual traits show similar or different aging dynamics is missing. The information is needed to assess if the signs are aging synchronously, as predicted by the William's antagonistic pleiotropy theory, or rather asynchronously. The suitable traits for study are these, which are involved in a reproduction activity. The reproduction is a sequential process consisting of many components, e.g. an expression of sexual ornaments (attractivity), nesting timing, amount of eggs laid and their size, etc. There is currently a little knowledge of which of these reproduction components are affected by the aging the most, and which are resistant to the the effect of age. Well studied is...
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Condition dependence of sexually selected ornaments in birds
Tomášek, Oldřich ; Albrecht, Tomáš (advisor) ; Verhulst, Simon (referee) ; Šálek, Miroslav (referee)
Sexual ornaments important for mating success in many species are often assumed to evolve as condition-dependent signals of individual quality. Ornament expression can be associated with age and survival, thereby signalling individual viability. Here, we have tested viability signalling function of tail streamers and their importance for within-pair and extra-pair fertilisation success in the European barn swallow (Hirundo rustica rustica). In contrast to previous studies on this subspecies, our data suggest that tail length is not associated with fertilisation success in our population. Instead, the most important predictors of within-pair and extra-pair fertilisation success were female and male age, respectively. Our data supported viability signalling function of male tail streamers, as documented by age-related within- individual increase in their length. There was no evidence for senescence in this trait. Contrary to some previous studies, the viability signalling function of tail streamers was further supported by observed selective disappearance of males with shorter tails. Several physiological mechanisms have been proposed as maintaining signalling honesty. Among them, oxidative stress from highly reactive species (RS), including free radicals, attracted a considerable attention. Given...
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Mechanisms of relationship between melanin-based colouration and behavioural syndromes in birds
Nacházelová, Martina ; Javůrková, Veronika (advisor) ; Tomášek, Oldřich (referee)
Melanins are the most common pigments incorporated into birds' feathers. Since melanin-based coloration is variable in the extent and intensity, its function is considered to be particularly cryptic and mechanical, hardening the feather structure. However, recently it has been found that melanin- based coloration also has a signaling function, due to the observed correlation between this type of coloration and many physiological and behavioral traits. These relationships follow from the pleiotropic effects of genes regulating the melanocortin system and the physiological effects of testosterone and corticosterone, which are involved in melanogenesis. This work describes genetic and physiological mechanisms of the relationship between melanin-based coloration and behavioral traits in birds and, based on available studies, supports the signaling function of this type of coloration. Melanin-based coloration has been shown to be positively correlated with aggressiveness and dominance, sexual activity, coping with stress, a fast strategy of exploratory behavior, parental care, and anti-predator behavior in many bird species. However, despite intense research interest in this topic in last decade, it is worth noting that more experiments focused on species with a distinct sexual dichromatism or...
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Seasonality of reproduction in tropical birds
Kačírek, Vojtěch ; Sedláček, Ondřej (advisor) ; Tomášek, Oldřich (referee)
The aim of of this paper is to summarize the knowledge of reproduction seasonality of tropical birds. Work includes characteristics of individual tropical environment and changes in abiotic conditions, focusing on the question, in what sense are tropics aseasonal and what is not. The work includes an overview of methodologies for collecting data during field research focused on monitoring reproduction in birds. The main part of this work is to compare the differences between biogeographic regions, regions and their stimuli, which most commonly lead to the creation of seasonal reproduction, followed by a comparison of individual functional groups of birds (food guilds). Powered by TCPDF (www.tcpdf.org)
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Postcopulatory sexual selection
Kivader, Tomáš ; Reifová, Radka (advisor) ; Tomášek, Oldřich (referee)
Sexual selection is a key evolutionary process which affects transfer of gene's alleles to future generations. We distinguish precopulatory and postcopulatory sexual selection. Postcopulatory sexual selection is a type of sexual selection which takes place after copulation, more specifically after insemination. During precopulatory sexual selection same-sex individuals compete over the opportunity to reproduce. Simultaneously, males and females have different priorities. Males prefer quantity while females quality of offspring. So they compete in creating new strategies for increasing their own fitness. Consequently, sexual selection often leads to coevolution between males and females of the same species. Finally, this affects the segregation of individual populations and speciation. For establishing postcopulatory sexual selection it is important that multiple males are mating with the same female within the scope of one population. This is ensured by promiscuity or extra-pair copulations in various mating systems. There are two basic processes by which postcopulatory sexual selection is realized. Those are sperm competition and cryptic female choice. These mechanisms have not been explored in detail yet. Firstly, because monitoring postcopulatory processes in vivo is problematic, and secondly,...
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