|
|
Personality differences in individuals of various sexual orientations
Fořt, Jakub ; Havlíček, Jan (advisor) ; Procházka, Ivo (referee)
The previous research identified a range of personality differences between men and women of various sexual orientations. Non-heterosexual individuals systematically show higher gender nonconformity and greater openness to experience than heterosexual individuals. Non-heterosexual men also show higher levels of neuroticism compared to heterosexual men. The main aim of this study is to replicate previous findings regarding personality differences. The study further aims to determine whether some of the observed differences in personality factors might be explained by differences in gender nonconformity among individuals of various sexual orientations. Via an online survey, a short version of the Big Five Inventory (BFI-10) and a number of scales measuring gender nonconformity were administered to men (N = 3,418) and women (N = 4,690). In total, 232 individuals identified as asexual, 1,814 as bisexual, 3,024 as heterosexual, 2,468 as homosexual, and 570 as pansexual. Our results demonstrate higher gender nonconformity among non-heterosexual men and women, higher neuroticism among non-heterosexual men, and greater openness to experience among bisexual men and women compared to heterosexual individuals. Asexual women showed lower levels of extraversion than women of other sexual orientations. Gender...
|
|
|
triggers of asexual reproduction: on the crosslink between hybridization, asexuality, polyploidy and speciation on example of Cobitidae loaches
Marta, Anatolie ; Janko, Karel (advisor) ; Arai, Katsutoshi (referee) ; Trachtulec, Zdeněk (referee)
(in English) Sexual reproduction is considered a nearly universal feature of all eukaryotic organisms and has been hypothesized to be their ancestral state. Sexual reproduction is mainly represented by meiotic division, recombination, production of haploid gametes and fertilization. Although molecular and cytological mechanisms underlying meiosis are highly conservative they may be disrupted in numerous ways leading to the emergence of so-called asexual lineages. The proximate origins of asexuality may differ for particular taxa. In vertebrates, asexuality frequently is triggered by interspecific hybridization. Nowadays "classical" theories predict that asexuals should not be able to persist on a long-term evolutionary scale. However, the hybrid lineages have to overcome short-term disadvantages, such as postzygotic barriers ranging from complete hybrid sterility to altered meiosis resulting in asexual reproduction and even ploidy elevation. Despite that hybrid sterility is one of the most common outcomes of interspecific hybridization, however various lineages found their ways to alleviate these problems and produce viable clonal gametes. The knowledge about proximate mechanisms of unreduced gamete formation in asexual lineages is very limited as many studies were restricted due to methodological...
|
|
|
Vliv polyploidizace a hybridizace na fyziologii reprodukce u ryb
TICHOPÁD, Tomáš
Sexual reproduction is one of the most common traits of eukaryotes and one of the most debated topics in biology. It involves complicated gene regulatory networks coordinating meiotic division, recombination, and the production of haploid gametes. Although these pathways are highly conserved, they have been repeatedly modified in many ways throughout the evolution of life forms. Interspecific hybridization and polyploidization are well known to alter the reproductive potential of an individual, and both phenomena are commonly linked with the so-called asexuality, i.e., the production of (partly) clonal gametes. Asexuality has attracted considerable attention as an excellent model to study the evolutionary dis/advantages of sex. Because of numerous associations with polyploidy, asexuals have also been considered as potential missing links in the formation of polyploid species. Nevertheless, asexual eukaryotic lineages are not an easily definable group. They are distributed throughout the tree of life and employ a broad spectrum of independently arisen mechanisms for gamete production. These mechanisms can noticeably differ even between closely related taxa, ranging from entirely ameiotic processes to those involving distorted meiotic divisions, which have different evolutionary consequences for each asexual lineage. It is therefore vital to understand whether there are any general rules followed in the processes leading to the abandonment of sexual reproduction or induction of sterility. This thesis investigates the effect of hybridization and polyploidy on reproductive modifications in several fish taxa. The first investigation was focused on the regulation of unreduced gamete production in asexual allotriploid females of Cobitis elongatoides-taenia-taenia. Naturally, it is accomplished via premeiotic endoreduplication (PMER) and followed by the pairing of sister chromatids. It has been discovered that the regulation of PMER is a female's exclusive trait, but the PMER execution depends on germ cell hybrid origin. Therefore, the asexuality phenotype in Cobitis is linked to phenotypic sex differentiation. Secondly, the spermatozoa characteristics of F1 hybrids of common carp and gibel carp were examined to evaluate morphological malfunctions. Males showed classical hybrid dysgenesis as their reproductive potential was negatively affected by the hybridization event, probably due to the high divergence between species. Although most of the spermatozoa were aneuploid or polyploid, a small fraction of spermatozoa was capable of fertilization and gave rise to F2 hybrid offspring. Thirdly, germ cells of ancestral hybrid Poecilia formosa were examined to confirm the PMER pathway; however, it was discovered that this species only initiates first meiotic genes, but meiosis itself is skipped. Therefore, P. formosa represents a rare exception to apomixis in fish taxa. Finally, a successful and effective protocol for triploid zebrafish production was established. Although the primary goal of this protocol was the establishment of sterile recipients for transplantation purposes, it represents an excellent opportunity for research of autopolyploidization effect on sex differentiation as all produced triploid zebrafish were confirmed as males.
|
|
|
Mechanisms of asexual reproduction in reptiles
Augstenová, Barbora ; Kratochvíl, Lukáš (advisor) ; Abramjan, Andran (referee)
In the case of reptiles, there has been described an occurrence of an asexual reproduction, especially in the case of a group Squamata; the asexual reproduction of birds (Aves) has been observed, too. Multiple times the asexuality of reptiles has been originated. Occurrences of obligate and facultative asexual species have been described. Most obligate asexual species have theirs origin in one or more hybridization events between closely related species. However, within the family Xantusiidae two exceptions where asexuality apparently originated without hybridization were discovered. Facultative parthenogenesis was originally expected only among reptiles kept in captivity, where the females were separated from males for a long time. However, this assumption was later disproved. The majority of the specimens formed by facultative parthenogenesis has reduced viability, which can be caused by the imperfect mechanism of the formation of parthenogenetic offspring. The terminal fusion is considered to be the probable mechanism of creation of diploid oocytes in the case of facultative parthenogenesis reptiles. The cytological mechanism of the parthenogenetic offspring's genesis was described for the obligate parthenogenetic species just for genus Aspidoscelis. During oogenesis in this case is ploidy...
|
|
|
Invisible sexuality: Specifics of the Life of Asexual People within Heteronormative Society
Andresová, Nela ; Hrešanová, Ema (advisor) ; Remr, Jiří (referee)
Thesis deals with social life of asexual people in the Czech Republic. The author focuses on the areas of acceptance of their own sexual identity as asexual, coming out and feelings of stigmatization, relationships and intimacy, belonging to LGBT+ community and the perception of the existence of a separate asexual community and the visibility of asexuality in society. For the purpose of the work was carried out qualitative research among asexual people, who selfidentify as asexual. The aim of the analysis was to determine how social life of asexuals differs within the heteronormative society. Thesis is based on differences between asexuals and heteronormative majority, especially in relationships and sexual behavior. The difference is also in other aspects of their life. People often don't know the meaning of asexuality, which can result in social stigmatization of asexuals due to pressure to accept a traditional model of relationship. In some respects, asexual people are similar to other sexual minorities, but not everyone feels to be part of LGBT+ community. Czech asexuals feel to be invisible in our society and they form networks among themselves through the internet forum asexual.cz. However, they don't create a separate community or social movement and they still remain socially invisible....
|
|
|
Mechanisms of asexual reproduction in reptiles
Augstenová, Barbora ; Kratochvíl, Lukáš (advisor) ; Abramjan, Andran (referee)
In the case of reptiles, there has been described an occurrence of an asexual reproduction, especially in the case of a group Squamata; the asexual reproduction of birds (Aves) has been observed, too. Multiple times the asexuality of reptiles has been originated. Occurrences of obligate and facultative asexual species have been described. Most obligate asexual species have theirs origin in one or more hybridization events between closely related species. However, within the family Xantusiidae two exceptions where asexuality apparently originated without hybridization were discovered. Facultative parthenogenesis was originally expected only among reptiles kept in captivity, where the females were separated from males for a long time. However, this assumption was later disproved. The majority of the specimens formed by facultative parthenogenesis has reduced viability, which can be caused by the imperfect mechanism of the formation of parthenogenetic offspring. The terminal fusion is considered to be the probable mechanism of creation of diploid oocytes in the case of facultative parthenogenesis reptiles. The cytological mechanism of the parthenogenetic offspring's genesis was described for the obligate parthenogenetic species just for genus Aspidoscelis. During oogenesis in this case is ploidy...
|
guest ::
