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Parental conflicts and speciation in the house mouse
Kropáčková, Lucie ; Reifová, Radka (advisor) ; Macholán, Miloš (referee)
Hybridization between closely related species of mammals is often accompanied by abnormal growth of placentas and fetuses. From the perspective of evolutionary biology, our knowledge about the contribution of such interspecies incompatibilities in speciation is still insufficient. In my thesis, I was finding out if abnormal placental and fetal growth contributes to reproductive isolation of two subspecies of house mouse, Mus musculus musculus and M. m. domesticus, which are at an early phase of speciation and in nature they still hybridize. Using two inbred strains derived from M. m. musculus (PWD/Ph, STUS) and two inbred strains derived from M. m. domesticus (C57BL6/J, SCHEST) we performed four different intrasubspecies and four different intersubspecies crosses. We found out that the size of the placenta in hybrids is more influenced by father, while the size of the fetus is more influenced by mother. After elimination influence of weight of mother and father we have not recorded a significant difference in the size of placentas and fetuses in intrasubspecies and intersubspecies crosses. Our results show that hybridization between subspecies of house mouse does not produce abnormalities in prenatal development, as was observed in hybrids between distant species of mice. It is thus possible that...
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Interspecific hybridization in Acrocephalus warblers.
Majerová, Veronika ; Reifová, Radka (advisor) ; Kotlík, Petr (referee)
Acrocephalus warblers have gone through the adaptive radiation during last severalmillion years, which gave rise to thirty one species occupying mainly Eurasia,Africa and Australia. The majority of species are morphologically very similar,however, they differ in ecological requirements, migration strategy, and song.Interspecific hybridization seems to be quite common among Acrocephaluswarblers, not only between sister species, but also between more distantly relatedtaxa. The main goal of this study was to determine whether this hybridization leadsto gene flow between species and which factors affect the rate of interspecific geneflow. For this purpose we conducted population-genetic analysis in three Europeanspecies of the Acrocephalus warblers of the subgenus Notiocichla: reed warbler (A.scirpaceus), marsh warbler (A. palustris), and blyth's reed warbler (A. dumetorum).Our results based on the analysis of sequence data from eight nuclear loci indicate,that gene flow between the studied species occurs, but only in one direction. Thegene flow is higher between genetically more related species than betweenecologically more similar species. We also estimated that the reed warbler and themarsh warbler diverged approximately 1,1 million years ago. The blyth's warblerand ancestor of the reed and marsh warbler...
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Characterization of Z chromosome gene content in birds
Mořkovský, Libor ; Reifová, Radka (advisor) ; Král, Jiří (referee)
Theory predicts that sexually antagonistic mutations will be over- or under-represented on the X and Z chromosomes, depending on the average dominance coefficient of the mutations. However, as little is known about the dominance coefficients for new mutations, the effect of sexually antagonistic selection is difficult to predict. To elucidate the role of sexually antagonistic selection in the evolution of Z chromosome gene content in chicken, we analyzed publicly available microarray data from several somatic tissues as well as somatic and germ cells of the ovary. We found that the Z chromosome is enriched for genes showing preferential expression in ovarian somatic cells, but not for genes with preferential expression in primary oocytes or non-sex-specific somatic tissues. Our results suggest that sexual antagonism leads to higher abundance of female-benefit alleles on the Z chromosome. No bias towards Z-linkage of oocyte-enriched genes can be explained by lower intensity of sexually antagonistic selection in ovarian germ cells compared to ovarian somatic cells. An alternative explanation would be that meiotic Z chromosome inactivation hinders accumulation of oocyte-expressed genes on the Z chromosome. Our results are consistent with findings in mammals and indicate that recessive rather than dominant...
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Evolution by gene duplication with regard to subfunctionalization.
Romášek, Marek ; Reifová, Radka (referee) ; Krylov, Vladimír (advisor)
Evolution by gene duplication has been a prominent topic of biology for various decades. Novel methods and approaches recently brought about a considerable progress in our understanding of this phenomenon. The aim of this thesis is to review the modern conceptions of preservation of duplicate genes in genomes of organisms and the processes involved. Another goal is to assess the significance of the concept of subfunctionalization, resolving of ancestral functions among the duplicates, leading to their preservation.
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Genetic conflicts and speciation
Kropáčková, Lucie ; Munclinger, Pavel (referee) ; Reifová, Radka (advisor)
In this thesis I'll examine the role of genetic conflicts in the origin of new species. Genetic conflicts can lead to an origin of reproductive barrier between the emerging species, especially postzygotic reproductive isolation. An example of such conflict could be meiotic drive on sex chromosomes, which distort sex ratio and seems to act a role in a hybrid male sterility. Another example may be genomic imprinting causing an abnormal placenta and embryo development in interspecies hybrids. Coevolution between cytoplasmic and nuclear genes can cause sterility of pollen in hybrids from plants. Similarly, the intracellular bacterium Wolbachia induces cytoplasmic incompatibility in animals. Mobilization of transposons may also lead to hybrid dysgenesis.
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Genetic basis of phenotypic variability in domesticated animals
Majerová, Veronika ; Komárek, Stanislav (referee) ; Reifová, Radka (advisor)
Understanding the mechanisms responsible for the origin of morphological variability among different species of animals represents an important goal in evolutionary biology. Origin and changes of the phenotypic variability during the evolution is possible to study in domesticated animals. The domesticated species of animals represent a brilliant model for studying the molecular mechanisms responsible for origin of new phenotypes due to enormous morphological variability of different domesticated breeds, effortless breeding in captivity and frequent knowledge of the genomic sequence. The aim of this bachelor work is to summarize actual findings about concrete mutations which are responsible for the origination of the new morphological characters in the domesticated animals. These findings can help us to clarify how the evolution functions on the molecular level.
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