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Vocalization of two nightingale species in their hybrid zone
Vokurková, Jana ; Petrusek, Adam (advisor) ; Osiejuk, Tomasz S. (referee)
6 ABSTRACT Bird song is a sexually selected trait that is crucial for mate choice and for maintenance of pre-mating reproductive barriers. Secondary contact of closely related and partially reproductively isolated song bird species may result in changes in their songs; these can either diverge and strengthen the reproductive barrier between the two species, or converge and contribute to mixing of their gene pools. The Thrush Nightingale (Luscinia luscinia) and its congener Common Nightingale (L. megarhynchos) may serve as model species suitable for studying these phenomena. In their secondary contact zone, an interspecific hybridization has been documented, as well as convergence of songs of Thrush Nightingales caused by copying of heterospecific songs. Such copying may be a result of erroneous learning of species- specific songs or by genetic introgression. We tested these hypotheses by simultaneous analyses of DNA and song recordings of both species from allopatry (Czech Republic and northeastern Poland) and sympatry (central Poland). Comparisons between our recordings and a catalogue of songs recorded in a Common Nightingale population from allopatry (Germany) confirmed that most of Thrush Nightingale males from the sympatric region were 'mixed singers' that use Common Nightingale phrases in their...
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Molecular and Genomic Methods for Analyzing Hybridization in Aspergillus and other Fungi
Jirkovský, Pavel ; Sklenář, František (advisor) ; Kolařík, Miroslav (referee)
Interpecies hybridization is being studied since the first half of 20. century, when it was described based on phenotypical traits on plant model. Study of this process was historically centred around botanical studies, while its importance in mycology is just being uncovered in recent years. Introgression is a phenomenon that can occur when hybrid backcrosses with one of the parental species. Based on recent studies it is apparent that hybridization played its role in evolution of MAT locus genes of Neurospora, transfer of adaptive traits with Ophiostoma species (invasive pathogen of elm trees). Within Aspergillus family hybridization was described both on intraspecific and interspecific level. More detailed study of this process and improving of used methods could potentially help in clinical application by uncovering adaptive genes responsible for resistance towards antimycotics, higher virulence and other traits.
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Anthropogenic hybridization between selected cultivated and wild relatives from the genus Malus (Rosaceae)
Orlovská, Lívia ; Slovák, Marek (advisor) ; Chrtek, Jindřich (referee)
Hybridization is an important driver of plant evolution, but it can also pose a threat to the genetic integrity of species. A specific case is gene flow induced by human activity, or "anthropogenic hybridization." In addition to theoretical knowledge about hybridization, introgression, and the protection of genetic diversity, this thesis presents its importance and impacts using the example of a model system from the Malus genus. By analyzing the available studies on the subject, I compare and evaluate the state of European populations of the wild species Malus sylvestris, which is subject to hybridization and introgression mainly with the cultivated species Malus domestica. The data indicate a common hybridization between these species to varying degrees, with up to 37 % of hybrid individuals in the population. The human effect is significant, particularly through the intensification of landscape utilization, which results in more frequent secondary contacts between species and subsequent gene flow. However, the available studies about hybridization between these species are mostly local, and a comprehensive view of the issue is lacking. Indeed, in the Czech Republic and Slovakia, there are presently no comparable empirical investigations utilizing genetic data. Overall, it implies that it is...
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Supplementations of the Mallard and their impact on wild populations
Pechmanová, Hana ; Musil, Petr (advisor) ; Kreisinger, Jakub (referee)
The Mallard (Anas platyrhynchos) is quite a popular game bird species. In many states, particularly in Europe and North America, captive-rearing and releasing of mallards has become common practice in wildlife management. The aim of these supplementations is to boost the size of hunted populations. More than three million Mallards are released each year. This paper aims to summarize and assess the potential effects of captivity-reared Mallards on the wild populations. Supplementations of mallards pose a threat to the genetic identity and variability of wild populations and may potentially lead to morphological and behavioral changes. Breeding facilities can be source of many pathogens, so supplementations may lead to transmission of these pathogens into wild populations. All the factors mentioned above may thus affect the fitness and population dynamics of wild Mallards. This paper also briefly considers how the releases can affect other species and the environment. This issue is not well studied so more studies and appropriate monitoring are needed for an assessment of the rate of these processes.
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Trans-species polymorphism in selected innate immunity genes in tits (Paridae family)
Těšický, Martin ; Vinkler, Michal (advisor) ; Štefka, Jan (referee)
Adaptation of host receptor system to optimal detection of infection-related structures is one of the key evolutionary challenges of immunity in host-pathogen interactions. Toll-like receptors (TLRs) are genetically variable molecules of vertebrate innate immunity that recognise danger signals, e.g. pathogenic molecules. Examination of genetic variation in TLRs may reveal mechanisms of host immunity adaptation to pathogenic pressure at molecular level. Trans-species polymorphism (TSP) is a phenomenon which assumes that several identical alleles or allelic lineages are inherited from ascendant to descendant species and these may be subsequently maintained over a long period of time in a polymorphic state. Whereas in adaptive immune genes the concept of TSP is well understood, little is presently known about TSP in innate immune genes such as TLRs. In this thesis I describe genetic polymorphism in functionally-relevant regions of TLR4 and TLR5 in 192 individuals representing 20 species Paridae family (tits, chickadees and titmice). These two receptors bind mainly bacterial ligands (TLR4 detects lipopolysaccharide and TLR5 detects flagellin), being among the first ones to trigger immune response to bacterial pathogens. To differentiate presumed TSP from gene flow among species, intron sequences of six...
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Introgressive zone of Arabidopsis lyrata and A. arenosa in Central Europe
Hojka, Jakub ; Marhold, Karol (advisor) ; Španiel, Stanislav (referee)
Genetic composition of hybrid zones often reflects geographical and ecological gradients. Hybrid zone of Arabidopsis lyrata and A. arenosa in Central Europe can be convenient model system for testing such hypothesis. These are well circumscribed but still interfertile, and their offspring is fully fertile. Besides repeated hybridisation events, the current state is complicated by the autopolyploidisation events of one of the parents, namely A. lyrata, which is present in the area studied both as diploid and tetraploid. This hybrid zone was already described in previous publications, which showed certain gradient of introgression. Moreover, the area of the hybrid zone represents a transition between Alpine and Pannonian climate along an altitudinal gradient leading from the Prealps to the lowland Wienerwald. The current thesis is the as yet most detailed study of this hybrid zone both in respect of number of studied populations and the amount of data acquired using the methods of RAD Sequencing, multivariate morphometrics and flow cytometry. The analysis of genetic data showed a gradient of introgression, where parental populations are placed at opposite ends, whereas genetically intermediate hybrids are placed in its centre. Analysis of the genome size showed an additional gradient, where hybrids...
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Evolution of intrinsic postzygotic reproductive isolation in birds
Opletalová, Kamila ; Reifová, Radka (advisor) ; Vošlajerová, Barbora (referee)
Hybrid sterility plays a key role in reproductive isolation during evolution of species. The mechanisms responsible for hybrid sterility are relatively well understood in organisms with heterogametic males, such as drosophila or mouse but are largely unknown in organisms with heterogametic females (e.g. birds). Studies on reproductive isolation in birds takes place in natural hybrid zones, instead of captivity. Hybrid sterility preferentially affects the heterogametic sex, males in mammals (XY) and females in birds (ZW), according to Haldane's rule. This leads to reduced introgression in sex chromosomes and mitochondrial DNA compared to autosomal DNA. The purpose of this thesis is to summarize known information on hybrid sterility and its expression in two models of interspecies hybridization: flycatchers and nightingales. Additionally, this thesis contains also a practical part, which compares morfology of sperms of two species of nightingales. Powered by TCPDF (www.tcpdf.org)
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Vocalization of two nightingale species in their hybrid zone
Vokurková, Jana ; Petrusek, Adam (advisor) ; Osiejuk, Tomasz S. (referee)
6 ABSTRACT Bird song is a sexually selected trait that is crucial for mate choice and for maintenance of pre-mating reproductive barriers. Secondary contact of closely related and partially reproductively isolated song bird species may result in changes in their songs; these can either diverge and strengthen the reproductive barrier between the two species, or converge and contribute to mixing of their gene pools. The Thrush Nightingale (Luscinia luscinia) and its congener Common Nightingale (L. megarhynchos) may serve as model species suitable for studying these phenomena. In their secondary contact zone, an interspecific hybridization has been documented, as well as convergence of songs of Thrush Nightingales caused by copying of heterospecific songs. Such copying may be a result of erroneous learning of species- specific songs or by genetic introgression. We tested these hypotheses by simultaneous analyses of DNA and song recordings of both species from allopatry (Czech Republic and northeastern Poland) and sympatry (central Poland). Comparisons between our recordings and a catalogue of songs recorded in a Common Nightingale population from allopatry (Germany) confirmed that most of Thrush Nightingale males from the sympatric region were 'mixed singers' that use Common Nightingale phrases in their...
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Hybridization and microevolutionary relationships among Central European Diphasiastrum species
Dvořáková, Kristýna ; Urfus, Tomáš (advisor) ; Chrtek, Jindřich (referee)
Genus Diphasiastrum Holub is one of the most complicated and biosystematically very little investigated groups within Lycopodiaceae family. There are 6 species recognized in Central European region. Three of them (D. alpinum, D. complanatum, D. tristachyum) are considered basic - parental taxa, and their hybridization probably gave origin to the three adjacent species - intermediates (D. issleri, D. zeilleri, D. oellgaardii). These supposedly hybridogenous taxa often co-ocur with at least one parental species. All the taxa often meet in secondary habitats where they tend to form hybrid swarms (e.g. on ski slopes which represent an ideal biocorridor for meeting the species from alpine zone with the species from lower altitudes). In such places reciprocal crossings between all of the taxa occur, often accompanied by introgression. The degree of hybridization, including the possible introgression, was studied using absolute genome size analyses combined with classical and geometric multivariate morphometrics. Genome size was estimated for 570 plants from 83 localities, mostly from the Czech Republic. Despite the fact that each parental taxa had a specific range of absolute genome sizes, adjacent species formed more or less disconnected continuum. Multivariate statistical methods (PCA, RDA, Loess, PLS)...
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Supplementations of the Mallard and their impact on wild populations
Pechmanová, Hana ; Musil, Petr (advisor) ; Kreisinger, Jakub (referee)
The Mallard (Anas platyrhynchos) is quite a popular game bird species. In many states, particularly in Europe and North America, captive-rearing and releasing of mallards has become common practice in wildlife management. The aim of these supplementations is to boost the size of hunted populations. More than three million Mallards are released each year. This paper aims to summarize and assess the potential effects of captivity-reared Mallards on the wild populations. Supplementations of mallards pose a threat to the genetic identity and variability of wild populations and may potentially lead to morphological and behavioral changes. Breeding facilities can be source of many pathogens, so supplementations may lead to transmission of these pathogens into wild populations. All the factors mentioned above may thus affect the fitness and population dynamics of wild Mallards. This paper also briefly considers how the releases can affect other species and the environment. This issue is not well studied so more studies and appropriate monitoring are needed for an assessment of the rate of these processes.
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