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The role of the FAR5 gene in alpine adaptation of Arabidopsis arenosa
Poštulková, Alžběta ; Bohutínská, Magdalena (advisor) ; Munclinger, Pavel (referee)
The repeated adaptation presents a unique opportunity to study the mechanisms of evolution in natural replicates. Repeated adaptation of Arabidopsis arenosa, a wild relative of the model organism Arabidopsis thaliana, to the alpine environment was previously studied. Genomic analysis by selection scans revealed a set of candidate alleles. Here, I present a functional follow-up study of a candidate alpine-adaptive allele of FAR5. Specifically, I asked: What are the characteristics of the alpine (A) allele compared to the foothill (F) allele? Is there any phenotypic effect of the two different alleles of FAR5? What are the environmental factors shaping the distribution of the alpine allele of FAR5 among the populations of A. arenosa? I first demonstrated that natural variation in FAR5 played a role in adaptation to the alpine environment: I identified four SNPs that were positively selected in the alpine populations across all five high altitude colonizations of A. arenosa. Three of these SNPs are coding and are linked together, forming a distinct alpine allele of the FAR5 protein. Using a unique crossing design based on a natural standing variation of the two identified FAR5 alleles, I prepared carriers of the non-native alleles on the genomic background of foothill and alpine populations. I then...
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What factors underlie gene reuse in adaptation?
Poštulková, Alžběta ; Bohutínská, Magdalena (advisor) ; Vosolsobě, Stanislav (referee)
Is the fate of a mutation predictable? The repeatability of evolution may indicate its predictability. If some change has emerged multiple times in the past, it may also occur in the future. Convergent evolution provides a natural model of repeated evolution and suggests the presence of certain constraints. Examination of the genetic processes, that have led to convergent adaptive traits, can contribute to the knowledge of the predictability of evolution. The aim of my work is to summarize the available knowledge about factors affecting gene reuse in adaptation. My work shows that the repeatability of evolution is biased by the genome characteristics, the population characteristics and also the trait encoding complexity. The likelihood of genomic region reuse increases with the amount of emerging mutations affecting the phenotype. Regarding the pleiotropic constraints of gene reuse, the most suitable is a mutation in the cis-regulatory region of the gene on the periphery of the functional pathway. Of the population traits, the greater effective size of the population, the higher standing genetic variation and the lower divergence between populations raise the chance of gene reuse. Despite the dependence of evolution on random processes, there are many factors that direct it and make it more...
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How predictable is genome evolution? Insights from convergent adaptations across Brassicaceae
Bohutínská, Magdalena ; Kolář, Filip (advisor) ; Novikova, Polina Yu (referee) ; Hobza, Roman (referee)
Adaptation, the process of propagation of beneficial mutations, enables populations and species to face changing environmental conditions. Cases of convergent (considered synonym to 'parallel' here) adaptation highlight natural selection's capacity to shape biological diversity, and provide natural replicates to investigate the extent of predictability in the genetic basis of adaptation. Recently, a wealth of genomic studies has identified widespread genomic convergence. However, the evidence has taken many forms, from responses in the same functions but different loci (function-level convergence) down to the precision of repeated adaptation via the same genes (gene reuse), raising a question if such variation can be explained by some unifying force/mechanism. It has been speculated that patterns of genomic convergence differ among studies because the scale of divergence differs from case to case. Yet, this observation has not been tested on a unified model system across a divergence continuum and so underlying factors remain unknown. In my PhD project I conducted an empirical investigation on how and why patterns of genomic convergence change with increasing divergence. To do so, I studied the genomic basis of convergent adaptation to outer (alpine habitats) and inner (whole genome duplication)...
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The strength and mechanisms of postzygotic breeding barriers between diploids and polyploids in plants
Petříková, Eliška ; Čertner, Martin (advisor) ; Bohutínská, Magdalena (referee)
The aim of this literature survey is to focus on whole genome duplication as a mechanism of sympatric speciation in plant populations, to explain the principals of reproductive isolation between neopolyploids and their diploid ancestors and to discuss the efficiency of reproductive isolation among various plant species. The mechanism of so-called triploid block will be introduced in this thesis. Triploids block is a form of postzygotic reproductive isolation which is realized during interpolidy crosses. The two main mechanisms of triploid block are the hybrid inviability, means production of inviable hybrid seed, and reduced fertility of triploid hybrids by production of aneuploid or inviable gametes. The efficiency of triploid block varies between plant species and these differences will be also discussed. The reduction in reproductive isolation often leads to gene flow between cytotypes. Mechanisms and intensity of gene flow between cytotypes of various species will be also introduced. In the end, this thesis will be enriched with a summary of existing knowledge about cytotype variability in populations of Butomus umbellatus, the model species for following master's thesis.
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