Evolution of the genus Hieracium - cytogenetic insights

• Název práce v češtině: Evoluce rodu Hieracium - cytogenetický náhled
• Název v anglickém jazyce: Evolution of the genus Hieracium - cytogenetic insights
• Akademický rok vypsání: 2022/2023
• Typ práce: disertační práce
• Jazyk práce: angličtina
• Ústav: Katedra botaniky (31-120)
• Vedoucí / školitel: doc. Mgr. Patrik Mráz, Ph.D.
• Řešitel: skrytý - zadáno vedoucím/školitelem
• Datum přihlášení: 05.10.2022
• Datum zadání: 05.10.2022

Předběžná náplň práce

This doctoral project is a part of a larger study (Young kids or old migrants? Colonization versus in situ speciation of allopolyploid apomicts in European alpine sky islands) that aims to decode the evolutionary history of allopolyploid apomictic (micro)species/populations (APAs) and the role climatic oscillations played in shaping their extant phylogeographic structures. To achieve these objectives, two high mountain apomictic groups of Hieracium that originated from different combinations of parental species: H. halleri (parental species H. alpinum and H. intybaceum) and H. nigrescens (H. alpinum and H. murorum) were selected. They represent two different distributional patterns since they differ in terms of morphological diversity, geographical distribution and range overlaps with their parental species. The combination of sexual and asexual reproduction within one genus, together with interspecific hybridizationmake the genus an excellent model for evolutionary and biogeographical studies.

In this context, the main goals of this PhD project are:
▪ To determine the parental genomic contributions in genomes of selected apomictic allopolyploids.
▪ To assesses putative chromosomal re-patterning that could be indicative for rare sexual events in apomicts.
▪ To provide karyotype evolution of diploid representatives of the genus.

In order to achieving these objectives, Genomic In Situ hybridization (GISH), Fluorescence In Situ hybridization (FISH) and flow cytometry will be used. By analysing the genome dosage of the putative parents, GISH will show the origin of APAs. GISH will be performed with labelled total genomic DNA of H. intybaceum and H. alpinum on chromosomes of H. halleri, and of H. alpinum and H. murorum on chromosomes of the H. nigrescens agg. Regarding FISH, three probes (5S and 45S rDNA, cl-82) will be used to explore the number and position of tandem repeats. Both, GISH and FISH, will be performed on one plant per population of each APA (45 plants in total). Besides, flow cytometry will be used to identify and verify the parental combinations differing in the genome sizes / ploidies and to assess the mode of reproduction. The absolute genome size will be estimated in 2 plants per population and screening of ploidy will be performed for 3 plants per population. Chromosomes will be counted for validation of the screening in the selected plants. Seed screen analysis will be performed on 20 seeds per plant, being five plants per population of the H. nigrescens agg. and H. halleri and a few plants of H. murorum analyzed (H. alpinum and H. intybaceum have been already studied). Karyotypes of diploid representatives of the genus will be mapped on the phylogenetic tree based on HybSeq data.

Předběžná náplň práce v anglickém jazyce

This doctoral project is a part of a larger study (Young kids or old migrants? Colonization versus in situ speciation of allopolyploid apomicts in European alpine sky islands) that aims to decode the evolutionary history of allopolyploid apomictic (micro)species/populations (APAs) and the role climatic oscillations played in shaping their extant phylogeographic structures. To achieve these objectives, two high mountain apomictic groups of Hieracium that originated from different combinations of parental species: H. halleri (parental species H. alpinum and H. intybaceum) and H. nigrescens (H. alpinum and H. murorum) were selected. They represent two different distributional patterns since they differ in terms of morphological diversity, geographical distribution and range overlaps with their parental species. The combination of sexual and asexual reproduction within one genus, together with interspecific hybridizationmake the genus an excellent model for evolutionary and biogeographical studies.

In this context, the main goals of this PhD project are:
▪ To determine the parental genomic contributions in genomes of selected apomictic allopolyploids.
▪ To assesses putative chromosomal re-patterning that could be indicative for rare sexual events in apomicts.
▪ To provide karyotype evolution of diploid representatives of the genus.

In order to achieving these objectives, Genomic In Situ hybridization (GISH), Fluorescence In Situ hybridization (FISH) and flow cytometry will be used. By analysing the genome dosage of the putative parents, GISH will show the origin of APAs. GISH will be performed with labelled total genomic DNA of H. intybaceum and H. alpinum on chromosomes of H. halleri, and of H. alpinum and H. murorum on chromosomes of the H. nigrescens agg. Regarding FISH, three probes (5S and 45S rDNA, cl-82) will be used to explore the number and position of tandem repeats. Both, GISH and FISH, will be performed on one plant per population of each APA (45 plants in total). Besides, flow cytometry will be used to identify and verify the parental combinations differing in the genome sizes / ploidies and to assess the mode of reproduction. The absolute genome size will be estimated in 2 plants per population and screening of ploidy will be performed for 3 plants per population. Chromosomes will be counted for validation of the screening in the selected plants. Seed screen analysis will be performed on 20 seeds per plant, being five plants per population of the H. nigrescens agg. and H. halleri and a few plants of H. murorum analyzed (H. alpinum and H. intybaceum have been already studied). Karyotypes of diploid representatives of the genus will be mapped on the phylogenetic tree based on HybSeq data.