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Host-microbiota, pro-inflammatory immunity and physiological senescence in wild birds
Těšický, Martin
Triggered by microbial ligands, inflammation serves as a "double-edged sword" to fight infections on the one hand, but on the other hand causing tissue damage due to oxidative stress if it is dysregulated. For example, chronic inflammation can contribute to inflammaging, which is now widely regarded as one of the causes of ageing. In my interdisciplinary dissertation, my colleagues and I investigated three interrelated aspects of inflammation, using an evolutionary framework and various free-living birds as models: (1) ecological and evolutionary determinants of gut microbiota (GM) composition and diversity, a driver of wild bird immunity, (2) diversity in immune genes affecting inflammatory responses in wild birds and (3) inflammation-related physiological senescence in a free-living passerine bird, the great tit (Parus major). Firstly, using 16S rRNA gene metabarcoding, we revealed high intra- and interspecific variation in passerine gut microbiota (GM) dominated by the major phyla Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Although in mammals GM depends strongly on host phylogeny and diet, in birds we found only moderate effects of phylogeny and very limited effects of host geography and ecology on GM composition. While microbiota diverged between the upper and lower...
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Host-microbiota, pro-inflammatory immunity and physiological senescence in wild birds
Těšický, Martin ; Vinkler, Michal (advisor) ; Tschirren, Barbara (referee) ; Štěpánek, Ondřej (referee)
Triggered by microbial ligands, inflammation serves as a "double-edged sword" to fight infections on the one hand, but on the other hand causing tissue damage due to oxidative stress if it is dysregulated. For example, chronic inflammation can contribute to inflammaging, which is now widely regarded as one of the causes of ageing. In my interdisciplinary dissertation, my colleagues and I investigated three interrelated aspects of inflammation, using an evolutionary framework and various free-living birds as models: (1) ecological and evolutionary determinants of gut microbiota (GM) composition and diversity, a driver of wild bird immunity, (2) diversity in immune genes affecting inflammatory responses in wild birds and (3) inflammation-related physiological senescence in a free-living passerine bird, the great tit (Parus major). Firstly, using 16S rRNA gene metabarcoding, we revealed high intra- and interspecific variation in passerine gut microbiota (GM) dominated by the major phyla Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Although in mammals GM depends strongly on host phylogeny and diet, in birds we found only moderate effects of phylogeny and very limited effects of host geography and ecology on GM composition. While microbiota diverged between the upper and lower...
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Mechanisms of reproductive isolation between two hybridizing passerine species, the common nightingale and the thrush nightingale
Poignet, Manon ; Reifová, Radka (advisor) ; Choleva, Lukáš (referee) ; Kratochvíl, Lukáš (referee)
iv - ABSTRACT (in English) - A key step in the origin of new species is the evolution of the reproductive isolation mechanisms separating the gene pools of newly emerging species. Despite a growing number of studies, we still know very little about the molecular, physiological and genetic mechanisms underlying reproductive isolation. Hybrid zones represent useful examples of ongoing species differentiation and can provide information about the nature of reproductive isolation separating the species and mechanisms facilitating or limiting the hybridization. Using two naturally hybridizing passerine species, the common nightingale (Luscinia megarhynchos) and the thrush nightingale (L. luscinia), we evaluated several mechanisms of reproductive isolation at the chromosomal, phenotypic, and genetic levels, with a focus on postmating prezygotic (PMPZ) and postzygotic isolation mechanisms. These nightingale species diverged ~1.8 Mya and currently hybridize in a secondary contact zone running across Central and Eastern Europe. First, we analysed the genetic composition of the secondary contact zone, demonstrating that parental forms are predominant in the hybrid zone, with few F1 hybrids (3.4%), early backcross hybrids (3.1%) and the absence of F2 hybrids. This suggests strong but incomplete reproductive isolation....
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Conservation genetics of Galápagos mockingbirds: from immune genes to genomes
VLČEK, Jakub
In this thesis I have dealt with the population genetic processes of mockingbirds in the Galápagos Islands ( Mimus ) in relation to the limited island area, from the perspective of two types of immune genes and the genome-wide approach. The thesis starts with an introduction to population genetic concepts relevant to conservation genetics followed by description of immune genes: the major histocompatibility complex (MHC) and the Toll-like receptors (TLR). In the final part of the introduction, I address how genetic drift, selection and inbreeding shape genome-wide genetic patterns in small populations. The introduction is followed by four chapters, beginning with an examination of MHCII polymorphism in populations of mockingbirds in the Galápagos Islands. The study of the relationship between MHCII and the abundance of ectoparasites is the content of the second chapter. The third chapter shows how polymorphism of TLRs is shaped by interaction of genetic drift and natural selection. The last chapter deals with the effects of limited island size on inbreeding and genetic load, supported by inferences of the past demography of mockingbirds. The thesis concludes with a summary of the results and their potential implications in the field of conservation genetics.
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Diversity and abundance of birds in 3D space of Žofínský prales primary forest
Kučerová, Eliška ; Hořák, David (advisor) ; Korňan, Martin (referee)
Bird species are specialized in diverse types of environments. Considering for example forest species, this does not mean that all species inhabit the same ecological niches. Some species occupy undergrowth while others prefer treetops. Some birds are bound to clearings and other gaps in forest cover, and other species require old trees with cavities. Primary Central European mixed forest is not a homogenous environment. But, on small spatial scales, the environment is very heterogeneous. We get an unprecedented variety of habitats especially when including the forest vertical dimension, which birds use much more than it is usually considered in studies. This diploma thesis describes in detail the bird assemblage in the Czech oldest nature reserve NPR Žofínský prales in which vegetation research is currently in progress. However, research dealing with bird mapping in forests still rarely consider the vertical dimension of the environment. Most bird censuses focus on the diversity of species at a site but usually do not include abundance of individual species. I, therefore, focused on a detailed mapping of the bird community on a 50-hectare area in NPR Žofínský prales. During the census, each bird and each bird's exact position in the 3D space of the forest were recorded. Special attention is paid...
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Habitat selection in post-breeding temperate forest birds
THRIKKADEERI, Karthik
Habitat selection of forest birds in Branišovský les, České Budějovice, Czech Republic was studied by observing habitat preferences in the non-breeding season and exploring possible shifts in preferences due to the changing seasons. Patterns of habitat selection were analysed at multiple levels: considering all bird species as well as comparing between two feeding guilds. Preferences were also studied by specifically monitoring predation rates by birds on artificial caterpillars and exploring changes with habitat and season.
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Kokcidie ptáků Galapág
KORDÍKOVÁ, Lucie
This study investigates coccidian parasites of the genera Eimeria and Isospora in faecal samples of birds from the Galapagos Islands. The study determines prevalence of coccidia on individual islands and bird species. Description of recorded coccidian parasites is based on morphological features of their oocysts as well as on phylogenetic relationships.
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