|
|
Evolution of Host Specialisation, Phylogeography and Taxonomic Revision of Xenidae (Strepsitera)
Benda, Daniel ; Straka, Jakub (advisor) ; Malenovský, Igor (referee) ; Cook, Jerry L. (referee)
Twisted-winged parasites (Strepsiptera: Xenidae) are an excellent group for studying the specialisation of parasites on hosts. Their parasitic lifestyle led to the evolution of numerous morphological, behavioural, physiological, and reproductive adaptations. Moreover, many complex adaptive traits of Strepsiptera have no parallel in other organisms. In contrast, little attention has been paid to the study of strepsipteran molecular phylogeny, phylogeography, species delimitation, and their implications for taxonomic classification. Using the methods of molecular phylogeny, we created the first dated phylogenetic study of the family Xenidae. By investigating historical biogeography and ancestral host groups, we indicate that multiple lineages were exchanged between the New World and the Old World + Australia until Antarctica became completely frozen over. During the late Paleogene and Neogene periods, several lineages spread from the Afrotropics to other Old World regions and Australia. The original hosts of Xenidae were most likely social wasps, and the subsequent host switch from social to solitary wasps was secondary and probably occurred only once. The parallel host switch from solitary wasps to digger wasps (Sphecidae) occurred independently in the New and Old World. The biogeography and...
|
|
|
Factors affecting pollen transfer effectiveness
Švanda, Petr ; Štenc, Jakub (advisor) ; Straka, Jakub (referee)
Pollen transfer efficiency, i.e., the proportion of pollen that is successfully transferred to a plant of the same species, significantly affects plant reproductive biology and creates a potentially strong selection pressure for the development of specialized strategies to increase pollen transfer efficiency. Precisely because of its importance within pollination biology, the efficiency of pollen transfer was a frequent subject of studies, in which, however, its interpretation differed depending on the method used, making it difficult to compare individual studies. Moreover, the work to date does not offer a satisfactory methodological framework for comparing the effectiveness of pollen transfer across the studied systems. The effectiveness of pollinators is primarily affected by the amount of pollen removed, the amount and quality of pollen deposited and frequency of pollinator visits. These factors are affected by additional influences, for example the behavior of the pollinator, the number of open flowers within the inflorescence or the environment variability. The result of this work is the retrieval of a methodological framework capable of determining and comparing the relevance of pollinators to pollen trasffer across plant species, which will be possible to link with theoretical models...
|
|
|
The Competition Among Pollinators and the Impact of Managed Bees on Wild Pollinator Populations
Voldřichová, Alžběta ; Straka, Jakub (advisor) ; Štenc, Jakub (referee)
Pollinators play an important role in ecosystems. Their ties to plants are essential for the reproduction of many plant species and thus for the protection of species diversity. Pollinator species therefore need to be protected. But to protect them effectively, it is necessary to understand the relationships between pollinators. However, the interaction between pollinators is a complex topic that needs further research. One of the current threats to pollinator populations is commercial pollinator rearing. Commercially reared species, especially Apis mellifera and Bombus terrestris, have been introduced almost all over the planet due to their positive effects on crop yields and its by-products. Moreover, in their native ranges they are bred in much higher concentrations than would be possible without human intervention. But high concentrations of commercial pollinators do affect populations of wild ones. This thesis describes forms of pollinator competition and addresses the impact of commercially reared pollinators on wild pollinator populations. KEY WORDS: Honeybee - Bumblebee - Hoverfly - Nest usurpation - Pathogen transfer - Species protection - Invasive species
|
|
| |
|
|
Population Genetics of Parasites and Their Arthropod Hosts
Bezányiová, Kateřina ; Straka, Jakub (advisor) ; Votýpka, Jan (referee)
Arthropoda are currently the largest metazoan phylum. Given that organisms with parasitic lifestyle are thought to comprise the majority of existing species, it's easy to imagine an immense diversity of parasites interacts with arthropods. However, in comparison to organisms parasitising vertebrates, parasites of arthropods are direly understudied despite their abundance, importance, and potential usefulness. Amongst other things, parasites can be used as tools allowing the inference of information on host life history, ecology, and past events the host species have experienced. Population genetic structure of parasites and other symbionts may reflect these traits and events due to their close relationship with the host. Even though parasites comprise a diverse assemblage of taxa, it's possible to identify convergent patterns in their biology. Models predicting congruent population genetic co- structuring can be thus based on a few traits such as host specificity, life cycle complexity or parasite and/or host dispersal. In some cases, the parasite may provide better resolution of population structure than the host itself, serving as a proxy that may be used to direct conservation programmes of both the host and parasite, as has already been done with parasites of vertebrates. This thesis summarises known...
|
|
|
Nesting behaviour and alternative reproductive tactics in solitary bees (Hymenoptera: Apoidea)
Rezková, Kateřina ; Straka, Jakub (advisor) ; Konvička, Martin (referee)
Proposed thesis describes nesting behaviour of gregarious solitary bee species Andrena vaga. The knowledge of behaviour in solitary bees can be very important, because solitarity might represent the initial point in the evolution of eusociality and obligate cleptoparasitism. A population of the studied species was observed continuously for two nesting seasons, which enabled me to describe basic demographic characteristics of studied species such as lenght of bee season, longevity, density of population, number of nests per female life, etc. All the observed behavioural patterns were described in ethogram and their exact position in provisioning cycle was determined. This information helped me to compile average daily activity of studied species. I found out major differences in bee behaviour in both years and between nonparasitized and stylopized (parasitized by Stylops) bees. I proved the existence of intraspecific cleptoparasitism in form of usurpations. Because it is crucial to link female to the provisioned cell for the detection of intraspecific cuckoo-like behaviour, I tested two new methods of underground cell marking - protein marking and fluorescent dye marking. Powered by TCPDF (www.tcpdf.org)
|
|
| |
|
|
Molecular identification of phlebotomine sand flies
Hlavačková, Kristýna ; Dvořák, Vít (advisor) ; Straka, Jakub (referee)
This diploma thesis is focused on species identification of sand flies belonging to two genera of the subfamily Phlebotominae, genus Phlebotomus and Sergentomyia. Genus Phlebotomus together with the genus Lutzomyia of New World include the only proven vectors of Leishmania parasites and they are also carriers of viral and bacterial infections. Species of the genus Sergentomyia are proven vectors of sister genus Sauroleishmania that infects reptiles, but for several decades there have been speculations about their possible involvement in the transmission of mammalian Leishmania species. These suspicions arise mainly from repeated findings of mammalian Leishmania parasites in their digestive system. Correct species determination of medically significant hematophagous arthropods is very important especially for purposes of epidemiological studies so that efficient vector control may be correctly set. Routine identification of sand flies is based on morphological characters located mainly on their heads and genitalia. However, these characters may be variable within a species, they require certain expertise and in the field samples they may be damaged, making proper species identification impossible. This thesis therefore presents two alternatives of sand fly identification based on molecular...
|
|
|
Biology of solitary bees of various families (Hymenoptera: Apoidea). A comarative study.
Žáková, Zdislava ; Straka, Jakub (advisor) ; Bogusch, Petr (referee)
The diploma thesis deals nesting behavior of the solitary bees Colletidae, Megachilidae, Mellitidae, Halictidae. The bees were monitored in their natural environment in the years 2009 - 2010. Course of their daily activities, number of nests per female, lenght of stay in the nest, length of life, active days and other species characteristics were monitored. By comparing the different nesting behavior patterns of the monitored species were found and pointed out the ones that are common and the unique ones. A nest uzurpation occurred (at all colonies) regardless the species. The (research) literature does not adress the issue of nest uzurpation in detail. Key words: nesting behavior, uzurpation, agression, bees, Hymenoptera
|
|
| |
guest ::
