|
|
Reactions of avian predators to automimicry in milkweed bugs (Heteroptera: Lygaeidae):
Stránská, Anna ; Exnerová, Alice (advisor) ; Baňař, Petr (referee)
Automimicry, or intraspecific variation in defence mechanisms in aposematic prey, is very common in nature. Especially in chemically protected prey. This study contains two experiments. The first experiment investigated the reaction of naive predators, which were Great tits (Parus major), to automimetic prey. The prey was the black-and-red-bug (Lygaeus equestris). The tits were divided into three experimental groups and each group was presented with three bugs that were fed on an artificial diet with different amounts of cardenolides. The control group was presented with prey that had no cardenolides in the diet. The group tested with the low concentration received bugs that fed on a diet with a low concentration of cardenolides and the group tested with the high concentration received bugs that fed on a diet with a high concentration of cardenolides. In a generalization test, all groups were then offered a single firebug (Pyrrhocoris apterus). It was found that the group tested with the high concentration experienced a higher rate of aversive learning. This group also killed and consumed fewer firebugs than the other two groups. The group tested with high concentration generalized most to novel red-and-black prey because they were least likely to attack the firebug. The second experiment tested...
|
|
|
Reactions of predators towards species of red-and-black mimetic complex
Kotlíková, Lucie ; Exnerová, Alice (advisor) ; Baňař, Petr (referee)
The red-black mimetic complex in the Western Palaearctic region includes a large number of arthropod species. These species differ in the degree of their mimetic resemblance, as well as in defensive mechanisms and their effectiveness against various predators. This study is based on two experiments. The first experiment was carried out with adult great tits (Parus major) and artificial prey (photographs). The birds were divided into two experimental groups and were trained to discriminate between palatable and unpalatable prey. One group was trained with higher diversity in the coloration of unpalatable prey (ten species of subfamily Lygaeinae), while the other was trained with low diversity in the coloration of palatable prey (ten individuals of the same species, Lygaeus equestris). After ten learning blocks, two generalization blocks followed, in which both groups received the same prey that was completely different from the prey during learning phase. The rate of learning was not significantly different between the two groups. However, more effective generalization was observed in the group trained with higher prey diversity. However, this trend was only observed in the first generalization block. On the second day, both groups achieved similar generalization success. The second experiment was...
|
|
|
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...
|
|
|
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...
|
|
| |
|
| |
|
|
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...
|
|
|
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,...
|
|
|
Diverzita kryptosporidií u pěvců
LIMPOUCHOVÁ, Zlata
This study was aimed on research of biology and diversity of Cryptosporidium in perching birds (Passeriformes). Presence of Cryptosporidium oocyst and specific DNA in faecal samples was detected by microscopy and molecular methods using nested PCR. Biological properties and intensity of infection of Cryptosporidium were examined and described in both experimentally and naturally infected animals.
|
|
|
Behaviour of avian predators to seed bugs (Lygaeoidea): effectiveness of chemical defence
Chalušová, Kateřina ; Exnerová, Alice (advisor) ; Sedláček, Ondřej (referee)
By warning signalling prey advertises its unpalatability to the predators. Typical examples are true bugs (Heteroptera) combining optical and chemical signals. The aim of this study was to find out the effectiveness of chemical defence against wild-caught adults of great tits (Parus major) and blue tits (Cyanistes caeruleus) and towards hand-reared juveniles of great tits. The tested prey were adults and larvae of two invasive species of genus Oxycarenus (Heteroptera: Oxycarenidae) (aposematic O. lavaterae, non-aposematic O. hyalinipennis), adults of Horvathiolus superbus (Heteroptera: Lygaeidae) and crickets (Gryllus assimilis) as a control prey. We were focusing on the influence of seed bugs to the initial reaction, the learning process and to the displays of discomfort behaviour in tits. Reactions affected by the tit species, age and sex were compared in adults. Juveniles were divided into two independent experimental groups, one group was offered adults of genus Oxycarenus, the second was offered sunflower (Helianthus sp.) or Digitalis sp. seed fed adults of H. superbus. The first bug offered did not elicit an initial aversive reaction in tits, but birds reacted aversively to the bugs after having further handling experience. All juveniles, contrary to the adult tits, attacked at least one bug...
|
guest ::
