|
|
Population genetics and speciation in Stylops (Strepsiptera)
Kodejš, Karel ; Straka, Jakub (advisor) ; Černá, Kateřina (referee)
This thesis is focused to population genetics of selected species of genus Stylops in Europe. Within this genus, five species was analysed by usage of two approaches - microsatellite analysis in Stylops ater and analysis of mitochondrial DNA in all five species. Mitochondrial gene for cytochome c oxidase (1st subunit) was used. For microsatellite analysis was performed bayesian clustering analysis and ABC approach (Aproximate Bayesian Computation). Mitochondrial markers were processed by making haplotype networks and demography analysis by computing Bayesian skyline plots. For Stylops ater, surprisingly low lewel of population subdivision was detected, yet with clearly differentiated population clusters from Scandinavia and baltic coast of Europe, which may imply period of isolation of these populations or relativelly recent population expansion and genetic differentiation due to lower population sizes. Next, hypotesis of possible temporal segregation of subpopulations of Stylops nevinsoni based on different aktivity period of their host species groups, was supported. In other three species, population subdivision was observed to be related either due to host specialisation (Stylops mellitae) or geographic consequences (S.nassonowi, S.spreta). Interesting finding is also detection of population...
|
|
|
Haldne's rule and mechanisms of hybrid female sterility in birds
Baránková, Lucie ; Reifová, Radka (advisor) ; Jansa, Petr (referee)
Hybrid sterility is one of the mechanisms of intrinsic postzygotic reproduction barriers between species and plays a key role in the process of speciation, which is emergence of new species. In accordance with Haldane's rule, hybrid sterility affects preferably the heterogametic sex, which means that in organisms with XY chromosomes, such as mammals or drosophila, male sterility will be affected by sterility of hybrid offspring, while organisms with ZW chromosomes such as birds or butterflies, will be a sterile hybrid female. Symptoms and mechanisms of hybrid sterility are well studied in organisms with heterogametic males, whereas far fewer studies have been performed on organisms with heterogamous females. In my bachelor thesis I will introduce the basic theories explaining the two general rules of speculation, the Haldane rule and the associated great influence of chromosome X or Z on the occurrence of hybrid sterility. Furthermore, in my work I will deal with the manifestations of hybrid sterility of females in birds and in the selected species will introduce the mechanisms that cause this sterility. Key words: Haldane's rule, hybrid sterility, speciation, birds, postzygotic izolation
|
|
|
The role of high-altitude habitats for speciation of central European endemics from the genus Campanula
Folbrová, Magdaléna ; Šemberová, Kristýna (advisor) ; Reif, Jiří (referee)
Mountain environment plays an important role in plant's life. Extreme conditions lead to continuous speciation accompanied by a complex processes e.g. geographical isolation (variation) or polyploidization. These processes can be studied by using a suitable model plant, represented in this thesis by selected mountain endemic bellflowers species belonging to Campanula rotundifolia agg. These species appear to be morphologically very similar but they are supposed to be of different origin. Mountain ecosystem is considered to be one of the most diverse and the most valuable environment for nature conservation. It hosts many endangered plants as well as plants protected by law. From the model group, these plants are represented by Campanula bohemica Hruby, Campanula gelida Kovanda and Campanula rotundifolia subsp. sudetica (Hruby) Soó. This thesis aims to sum up the up the current knowledge about a high altitude environment and endemism and to give a description of speciation mechanisms leading to the variability of mountain Campanula species. Further descriptions of their endangerment level, conservation and origin are also given. The subsequent MSc Thesis, introduced in the last part of this thesis, aims to reveal the origin of Czech and Slovakian mountain Campanula endemics. It is mainly focused on...
|
|
|
Genomic approach in speciation studies
Habalová, Kateřina ; Hulva, Pavel (advisor) ; Mikulíček, Peter (referee)
Speciation, adaptation and hybridization are three concepts, each one referring to different process but having a common evolutionary context. Maternal line splits into two sister lines or only one line cleaves from maternal one during speciation. However it leads to formation of new species. Adaptation and hybridization can lead to formation of new species as well. New species arise by adapting to new conditions during adaptation. Within hybridization it is a desecendant of two different lines mating amongst themselves. Most of this thesis is being addressed to these issues, the lesser part is addressed to specific examples. The chapter about next-generation sequencing methods is also included, as these methods have been used more frequently recently. Key words: speciation, adaptation, hybridization, genomics, next-generation sequencing
|
|
|
Variability in health state of mice in Mus musculus musculus and Mus musculus domesticus hybrid zone
Bílková, Barbora ; Vinkler, Michal (advisor) ; Vetešníková Šimková, Andrea (referee)
House mouse hybrid zone is a complex of subspecies Mus musculus musculus, Mus musculus domesticus and their hybrids. This hybrid zone is considered as a tension zone, maintained by balance between dispersion of individuals towards the zone center and negative selection against the hybrids. Decreased anti-parasite resistance could be one of selective factors which maintain the hybrid zone. In this thesis, I use hematological methods and skin-swelling test to compare variability in mouse health state within the house mouse hybrid zone. The skin-swelling test is a method measuring pro-inflammatory immune responsiveness. Since the commonly adopted method to perform this test does not allow clear interpretation of the test results, in this thesis I also aim to optimise the test protoco . I found that utilization of concanavalin A (ConA) is more suitable in mice than application of the commonly used phytohemaglutinin (PHA). Assessment of health state of mice by both hematological methods and skin-swelling test consistently indicates increased ability of anti-parasitic resistance in the subspecies M. m. musculus compared to subspecies M. m. domesticus. Hematological examination further shows better health state of hybrid individuals compared to parental subspecies. Our results support hybrid resistance hypothesis....
|
|
|
Endemic plants of the Sudeten Mts., with emphasis on the taxonomically controversial Primula elatior subsp. corcontica
Konečná, Veronika ; Suda, Jan (advisor) ; Knotek, Adam (referee)
The endemic species of the Czech Republic still present a hot topic. Effective research of this topic means understanding of factors which create and influence endemism. With the exception of the Alps and the Carpathians, endemics are relatively very rare in Central Europe. In the Czech Republic they are concentrated mainly in subalpine (alpine) areas in the High Sudetes. Majority of the Czech endemics is of relatively recent origin. They have not well differentiated yet and so it is difficult to taxonomically evaluate them. Endemics of the High Sudetes have probably originated in Holocene with the exception of apomicts, e.g. species of genus Hieracium, which have likely originated even earlier. The origin of most of the Sudetes endemics was possible due to geographic isolation of small populations called peripatric speciation. Peripatric speciation is probably responsible for the origin of taxonomically uncertain endemic species Primula elatior subsp. corcontica, which is a subspecies of highly variable P. elatior. In the Czech Republic occur three subspecies of P. elatior - subsp. corcontica, subsp. elatior and subsp. tatrensis. These subspecies are differentiated in the morphology of leaves and in their distribution. The description of P. elatior subsp. corcontica was based on morphological...
|
|
|
Sources of Sorbus aria agg. variation
Bílá, Jana ; Urfus, Tomáš (advisor) ; Krahulec, František (referee)
The main drivers of microevolution in the genus Sorbus are interspecific hybridisation and polyploidy. The fate of new hybrid and polyploid taxa is determined by their mode of reproduction. Especially apomixis could be very advantageous for these new taxa. The S. aria agg. (subg. Aria) plays an important role within the genus since its members are involved in all hybridisation events and thereby is responsible for the substantial part of variation of the genus. Flow cytometry, molecular markers and multivariate morphological analyses were employed to evaluate the processes generating the variability in the S. aria group. Three ploidy levels were detected among species from subg. Aria in the Czech Republic. All of them could be found in the South Moravia, whereas only tetraploids occur in the Bohemia region. Moreover, most of the Czech taxa (5 out of 7) grow also only in the South Moravia which is therefore considered as a centre of diversity of the genus Sorbus in the Czech Republic. Flow cytometry seed screen revealed 7 modes of reproduction among the individuals from S. aria agg. A wide range of sexual and apomictic types of reproduction including reduced and unreduced gametes was detected. All of the diploid individuals are completely sexual. Among polyploid taxa, most of the species are...
|
|
|
Limitation of species richness
Szostoková, Kateřina ; Storch, David (advisor) ; Šímová, Irena (referee)
Currently we can find two main hypotheses of diversity dynamics in time in literature - bounded and unbounded hypothesis. According to bounded hypothesis diversity is limited, while unbounded hypothesis says that there are no obvious limitations of diversity. Evidence for these main hypotheses comes mainly from paleontological research, studies of phylogeny and comparison of local and regional diversity. None of these approaches give us clear and incontrovertible evidence of diversity limits. The aim of this work is to show some evidence that confirm (or not) limitation of diversity in mentioned kinds of biological research. Also, I would like to point out some critics and imperfections of used methods.
|
|
| |
|
|
Speciation of the genus Lethrus (Coleoptera: Geotrupidae) of the eastern mediterranean
Drožová, Dana ; Janšta, Petr (advisor) ; Bezděk, Aleš (referee)
Earth-boring dung beetles of the genus Lethrus Scopoli, 1777 belong to the family Geotrupidae, classified into three subfamilies (Geotrupinae, Lethrinae a Taurocerastinae). The description of about 120 species, divided into nine subgenera, is based on morphology and geographic distribution. Shape of mandibles, ventral mandible processes, pronotum and structure of external male genitalia are used as diagnostic morphological characters for taxa. The richest species diversity is known from Central Asia. The distribution area reaches, in the east, up to Mongolia and China, and in the west, up to Southeast Europe. All species are robust, relatively large flightless beetles with low dispersial ability. They feed on parts of fresh plants instead of feces like other dung beetles. Master thesis is focused on the species distributed in the Eastern Mediterranean and Central Europe. This area is inhabited only by nominotypical subgenus Lethrus. The main goal of thesis is to clear up phylogenetic relationships between species of subgenus and speciation events using molecular genetic methods. We have examined 91 samples of the genus Lethrus using two mitochondrial genes - cytochrome b (382 bp, 80 sequences), cytochrome oxidase I (815 bp, 87 sequences) and nuclear gene 28S rDNA (D2-D5) (1100 bp, 11 sequences)....
|
guest ::
