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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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Výstražná signalizace barevných forem slunéčka východního (\kur{Harmonia axyridis})
BOROVIČKA, Martin
The efficiency of the aposematic defenses (colouration and chemical defence) used by three rare colour forms of Harmonia axyridis were tested using in the wild caught great tits (Parus major) as predators. I predicted that visually orienting predator will pay more attention to the rare colour forms, as they are not familiar with them and need to generalize the learned aversion to some other ladybirds to these novel ones.
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The effect of a predator occurrence on vigilance of tits visiting the winter feeder
Tichá, Irena ; Fuchs, Roman (advisor) ; Sedláček, Ondřej (referee)
This thesis evaluates the vigilance parameters of two species of tits affected by the presence of a predator in wintertime. During preferential experiments, tits have had a choice of two feeders in the vicinity of the installed dummy predator. For that purpose was used a dummy sparrowhawk, incomplete or occluded sparrowhawk torsos, and harmless pigeon. It is known that the tits are able to recognize dangerousness presented by the dummy, and according to expected risk dare to visit one of the feeders. It leads to a question whether the tits are somehow influenced by the presence of the dummies, and if so, how specifically are they influenced. It turned out, that the tits in presence of a dangerous dummy significantly increased their vigilance. Both observed species at the feeders behave oppositely. Behaviour of all the birds at the feeder is also affected by their total count at the precise moment and by the presence of a dummy at the other feeder.
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Factors influencing effectiveness of aposematic signals against avian predators
Kuklová, Lucia ; Exnerová, Alice (advisor) ; Krištín, Anton (referee) ; Sedláček, František (referee)
This thesis focuses on various factors affecting effectiveness of aposematic signals against avian predators. Adult, wild-caught as well as hand-reared juvenile great tits (Parus major) were used as predators in the experiments. The thesis consists of the following four studies. In the first study, we compared the reactions of great tits from two geographically distant populations toward aposematic firebugs (Pyrrhocoris apterus) and their non-aposematic artificially made colour variant. The birds from the Bohemian population mostly avoided aposematic firebugs and attacked non-aposematic variant. Finnish birds, which lacked experience with firebugs from their natural environment, were less hesitant to attack both firebug colour forms. Although the Bohemian birds avoided the aposematic prey variant, they were not more neophobic than Finnish birds. We conclude that the geographic differences in reactions of the birds to aposematic prey can be explained by a different population-specific experience of the birds with local aposematic prey communities. In the second study, we compared effectiveness of two chemical defence strategies in leaf beetle larvae (Chrysomela lapponica) against great tits. The birds avoided larvae devoid of external secretions after the first attack, which indicates the presence...
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Effect of type of discrimination task on rate and effectiveness of discrimination learning to avoid aposematic prey in avian predators
Jůnová, Lenka ; Exnerová, Alice (advisor) ; Sedláček, Ondřej (referee)
During the proces of learning to distinguish between edible and inedible prey, predators can encounter different types of prey either sequentially (one at a time) or simultaneously. Sequential as well as simultaneous presentation are used as experimental designs for testing discrimination learning of bird predators in relation to aposematic prey. These tasks can differ in difficulty level for predator which can affect test results; however, rate and effectivity of discrimination learning in sequential and simultaneous tasks have never been experimentally compared. We tested effect of type of discrimination task on effectivity of discrimination learning and memorability of prey discrimination in adults and juveniles great tits (Parus major) in two sequential tasks (regular and random) and one simultaneous task (multiple- choice). The birds learned to discriminate between edible and inedible artificial prey on the first day, and we investigated memorability of prey on the second day. We used colour (alternative red/green) or pattern (alternative dots/stripes) as discrimination cue. Results showed that tits learned to discriminate by colour cue better than by pattern cue. Adult tits learned to discriminate better than juveniles independently on task type. Effect of age and sex was shown in some tasks...
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Effect of ageing on haematological and immunological traits in great tit (Parus major)
Krajzingrová, Tereza ; Vinkler, Michal (advisor) ; Remeš, Vladimír (referee)
v III. Abstract (EN) According to the Disposable soma theory, senescence is mainly influenced by adaptive allocation of resources among the physical growth, reproduction and self-maintaining processes, which depend on expected survival of an individual. The amount of allocated resources may be influenced by external environmental factors such as heavy metal pollution or by inner factor e.g. reproduction. The aim of my diploma thesis was to clarify the relationships between senescence, selected haematological traits, reproduction and efficiency of innate immunity mechanism. Moreover, we are interested in the role of heavy metal pollution in ageing and haematology. The heterophiles to lymphocytes ratio (H/L) was used as a marker of long-term stress caused by these physiological expenses. This study summarizes partial data collected within the long-term research of great tits (Parus major) in Prague, Czech Republic, I participated in. We have more than 300 samples of repeatedly captured individuals at our disposal. The structure of this unique dataset allows us to observe changes in the traits of our interest during an avian lifespan. Our results show that during aging, males experience a noticeable increase in the H/L ratio compared to females. Although we have not found the effect of age on the brood size,...
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Bird responses to the invasive lime seed bug (\kur{Oxycarenus lavaterae})
MEJDA, Tomáš
Oxycarenus lavaterae is species of Heteroptera and possessing pink blots on corium and distinctive, gleaming membranaceous wings. This appearance could correspond to the definition of a warning color. The design is similar to other coreoid Heteroptera, which live in the Czech Republic; though Oxycarenus lavaterae is a species originating from Mediterranean and quickly spreading north. In Czech Republic it is a new species and predators thus have only short experience with it.The information about chemical protection of Oxycarenus lavaterae is weak and the effect on predators has never been tested. The characteristic behaviour for this species is creating large aggregations, primarily at the time of hibernation. At that time, several thousands of individuals are gathered in apertures or at the surface of tree bark. The aggregation may enhance the warning appearance of this species. The aim of this study was to test the response of bird predators to the adult individuals of Oxycarenus lavaterae. Three species of insectivorous birds differing in the level of foraging and diet specialization was chosen as predator (namely - Great tit (Parus major), Blue tit (Cyanistes caeruleus), Eurasian blackcap (Sylvia atricapilla)). Unmodified individuals of Oxycarenus lavaterae were served to these predators. In the case of the Parus major, the aggregation of Oxycarenus lavaterae (about 100 pieces) was also presented to test the effect of gregarious behavior on the warning signal. This study showed that the Parus major and the Sylvia atricapilla attacked the individual Oxycarenus more often than the Cyanistes caeruleus showing high level of restraint. In experiments with aggregatedOxycarenus lavaterae Parus major attacked them less often than when presented solitarily. However, after eating some Oxycarenus lavaterae, the Parus major showed symptoms of disgust and loss of appetite.
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Effect of social learning on avoidance of aposematic prey in avian predators
Bělová, Magdalena ; Exnerová, Alice (advisor) ; Sedláček, František (referee)
Social learning is a topic of many studies. We tested the effect of social learning on the acquisition of avoidance against aposematic prey. We have chosen wild-caught adult and naive hand-reared juvenile great tits (Parus major) as a model predator species, because their individual avoidance learnig of aposematic prey is well-studied. We used red and green paper dummies of bugs with a mealworm (Tenebrio molitor) stuck underneath as an artificial prey. Mealworms were soaked in water or in bitter-tasting solution of quinine. We used two types of conspecific demonstrators - naive birds that showed aversive reactions while tasting an unpalatable prey and experienced birds that were trained not to handle the unpalatable pray at all. We compared effects of both demonstrators on discrimination learning and we tested whether these effects differ in adult and juvenile birds. Observing an experienced demonstrator had an effect on the performance of observers at the beginning of learning process. The observers did not reject the unpalatable prey completely, but the number of trials in which they correctly chose the palatable prey was higher in comparison with birds that observed naive demonstrators and birds from the control group with no demonstrator. Latencies to handle the unpalatable prey in the first...
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