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Nest construction
Jenšovský, Václav ; Kreisinger, Jakub (advisor) ; Šulc, Michal (referee)
The nest is in the life of birds important structure. It's a place where kept for posterity during the entire period of reproduction. For this to be nest offspring suitable place for development, must have a specific structure which is variable for each species. Variability, whether at the level of intraspecific and interspecific level and is influenced by several factors. These factors include thermal insulation properties, antipredatory properties, further property to protect the nest before (ecto) parasites, but also can design nest pose as a selectable character sexually. Each of those factors differently closer together, but often one factor may disadvantage second and thus reduce the success of rearing offspring. Key words: nest construction, thermal insulation properties, antipredatory properties, ectoparasites, sexual selection
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Sexual selection in Scarab beetles with empahsis to the subfamily Scarabaeinae (Coleoptera: Scarabaeoidea)
Kněnická, Kateřina ; Šípek, Petr (advisor) ; Král, David (referee)
Sexual selection is a very important phenomenon in nature. In this work, I focused on the mechanisms of sexual selection in scarab beetles, with a strong emphasis on group Scarabaeinae (Coleoptera: Scarabaeoidea: Scarabaeinae). The first part is devoted to selection and its classification the sexual reproduction and related effects. I tried to describe the list of forms of sexual dimorphism in individual families and groups of Scarabaeoidea and describe life strategies subfamilies Scarabaeinae. Finally I list the factors influencing the individual the attractiveness in the relation to mating success. Powered by TCPDF (www.tcpdf.org)
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The role of imprinting-like effects and social learning for persistence of variability of iris and hair color in European population
Joudal, Lukáš ; Kleisner, Karel (advisor) ; Bártová, Klára (referee)
In bachelor's thesis I deal with the influence of various factors on the color of hair and eyes of the European population. In Europe, many still find blond and light eye colour population despite there is much darker colored populations. Here are some of the mechanisms causing maintain high polymorphism in the European population. The first part of bachelor's thesis focuses on a brief description of the structure of the European population. The thesis also discusses the genetic determination of hair and eyes, its diversity and the differences of the population from the populations of Asia and Africa. In the next section, we discuss the emergence and spread of recessive alleles light eye color a blonde in Europe, particularly northern Europe. The following is a description of the mechanisms influencing the propagation and conservation of recessive alleles. In the penultimate chapter describes the relationship between the morphology of the face and eye color, and the last chapter summarizes the effects mentioned in the previous chapters and their effect on the length of the relationship between partners.
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Acoustic and visual signalization in birds: Identification of key components and their role in sexual selection
Mikula, Peter ; Albrecht, Tomáš (advisor) ; Svobodová, Jana (referee)
This bachelor thesis is focused on describing visual and acoustic signals in birds and their potential role in the process of sexual selection. Evidence that acoustic and visual signals are sexualy selected is summarized. The key characters that can be utilized in comparative studies are determined. In the first chapter of the thesis are briefly outlined mechanisms of sexual selection and evolution of costly secondary male ornamentation. In the second chapter basic avian ornaments (colouration, acoustic signals) are described. The emphasis is on visual and acoustic structures which are costly to produce and serve as honest indicators of individual condition. The third chapter is devoted to the possible trade-offs between visual and acoustic signalization in birds. The last section summarizes hypotheses about potential relationships between visual and acoustic signalization (and trade-offs between these two types of ornamental traits) in relation to changing environmental conditions.
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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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Sperm strategies in rodents
Šandera, Martin ; Stopka, Pavel (advisor) ; Macholán, Miloš (referee) ; Sedláček, František (referee)
Rodents exhibit diverse biology, mating systems and diverse sperm morphology. Different levels of sperm competition have therefore been found in this group. Generally, it is accepted that sperm competition in animals causes the prolongation of sperm tails. However, what other sperm morphological adaptations in rodents are affected by sperm competition? Species-specific sexual selection likely optimizes sperm morphology. Sperm physiology, morphology and competition may be influenced, ultimately, by environmental factors. This Ph.D. thesis focuses on sperm competition in murine rodents. The thesis contains three research articles (including one as a submitted manuscript). In addition, another published article, partialy related to the topic of this thesis, is represented in the Appendix. The sperm morphology in rodents plays an important role in sperm competition. Longer tails and apical hooks are usually found in the species with relatively larger testes and with higher percentage of multiple paternity (i.e. rate of promiscuity), that is in species with the higher risk of sperm competition. The goal of the first study was to investigate the relationships between relative testis weight and sperm traits (apical hook and tail lengths and variance in this traits). The apical hook length was positively...
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Male quality, extrapair paternity and parental investments in scarlet rosefinches
Schnitzer, Jan ; Albrecht, Tomáš (advisor) ; Fuchs, Roman (referee) ; Šálek, Miroslav (referee)
Social monogamy, closely associated with bi-parental care, is the most frequent pairing system found in birds. Because females invest more into the reproduction, they are usually considered to be the sex that chooses the partner. To satisfy female preferences in the mate choice males in various species developed a number of traits that signalize their quality. What qualities are signaled by these traits and what mechanisms are responsible for the emergence, development and maintenance of these traits is the subject of a number of evolutionary- ecological studies. By pairing with an appropriate male female can obtain direct or indirect benefits to its own fitness. The good parent theory suggests that male secondary sexual traits signalize male ability to provide parental care (a direct benefit). An indirect benefit is presented by the quality of the genetic material that the female obtains from male for her offspring. According to the good genes hypothesis females use secondary male ornamentation to assess genetic quality of males. One of the most studied secondary sexual ornaments that can advertise male quality and may be used in mate choice by females is the plumage colouration. In many avian species there is sexual dimorphism in the plumage colouration and there is also growing evidence that...
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Vliv stavu a funkce imunitního systému na pohlavní výběr u ptáků
Vinkler, Michal ; Albrecht, Tomáš (advisor) ; Kleven, Oddmund (referee) ; Grim, Tomáš (referee)
Evolution is a most fascinating feature of all living things in our world. The means of organismal evolution are diverse, comprising mainly of natural and sexual selection. Both of these phenomena may contribute to evolutionary adaptations in health and disease. The questions of immunity impact on the process of sexual selection and sexual selection for increased anti-parasite resistance are wide issues of the present research in natural sciences. Their clarification requires multidisciplinarily-based investigation combining a variety of partial results into a single united paradigm. My co-workers and I have chosen several specific issues to study, in order to fill some of the important gaps of the current knowledge. We proposed the Carotenoid maintenance handicap hypothesis to point out that optimisation instead of maximisation of the carotenoid intake and ornamental display may be physiologically convenient for the individual. In Scarlet rosefinch (Carpodacus erythrinus) we confirmed the role of the carotenoid-based ornamental colouration in the process of sexual selection and investigated several partial aspects of the association between immunogenetics, immune function, health and the ornament expression and mate choice. In Zebra finch (Taeniopygia guttata) we have shown that the present way of...
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