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Ambrosia galls - neglected model of fungus farming evolution
Zelinková, Barbora ; Kolařík, Miroslav (advisor) ; Janšta, Petr (referee)
Ambrosia galls are a unique type of insect gall created by Cecidomyiidae gall midges. Their association with a fungal symbiont, which forms a layer of ambrosia mycelium inside the gall is unique and reminiscent of fungal farming in other insect groups. To date, not much research has been done on the individual components of ambrosia galls: the galling insect, the symbiotic fungus, and the host plant. This paper provides an insight into fungal farming insects, a description of the ambrosia gall midges and their fungal symbiont, an overview of the mechanisms of each component on gall initiation and the relationships between them, and finally, explores the possible influence of fungal secondary metabolites. The bachelor thesis puts into context long-known and newly acquired information on the mutual interactions and shows that the previously accepted functions are not precise and that each component of the ambrosia gall is partially involved in its formation. Key words: ambrosia gall midges, nutritive mycelium, fungus farming, host specialization, species diversity, phyto-mycophagy, trophic interactions, Cecidomyiidae, Botryosphaeria dothidea, secondary metabolites
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Evolution of host specificity and phylogeography of Strepsiptera parsites of the family Xenidae
Benda, Daniel ; Straka, Jakub (advisor) ; Malenovský, Igor (referee)
The twisted-wing parasites (Strepsiptera) are an endoparasitic order of insects with cosmopolitan distribution, which are sister group of Coleoptera. There are about 600 known species up to date. Strepsiptera parasitize seven insect orders (Thysanura, Orthoptera, Blattodea, Mantodea, Hemiptera, Diptera, Hymenoptera). The family Xenidae is one of the most derived groups of Strepsiptera. Its representatives parasitize aculeate Hymenoptera of three families (Vespidae, Sphecidae, Crabronidae). In comparison to the basal groups, there are well-known hosts for genera of the family Xenidae. Therefore, this group is suitable object for study of the evolution of host specialization. Phylogeny of the family Xenidae was constructed on the basis of molecular analysis of three genes. Moreover, the mapping of ancestral host major groups and biogeographic areas was performed using two methods (parsimony, maximum likelihood). According to the results, the family Xenidae is monophyletic group with Old World origin. There were a several independent switches to the same host groups. This significantly changes the existing ideas about evolution of host specialization and requires a taxonomic revision. Within the family Xenidae, there were several cases of dispersal between the Old World and the New World. Furthermore,...
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Food and host specialization in Aculeata (Hymenoptera)
Hochová, Veronika ; Policarová, Jana (advisor) ; Černá, Kateřina (referee)
Aculeata is a group of insects, its representatives vary significantly in the use of resources which are necessary for its survival and reproduction. Herbivores which live on parts of plants, carnivores which hunt other insects and omnivores are included in this group. There are also parasitic species such as cleptoparazites, brood parasites or parasitoids classified in Aculeata. Particular groups of Aculeata are adapted to resourcing, these adaptations exist in adult and immature stages simultaneously. Adaptation to the kind of source can lead to adjustment of mouthpart for easier prey hunting or nectar collecting, corbicula and special hair intended for collecting pollen or oils, a sting used for incapacitate the host or a sting for defense. Aculeata varies to such an extent how they are specialized in food and the host. Aculeata incorporates closely specialized species together with generalized species. The known information about the specialization Aculeata on food and host is summarized in this thesis.
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Evolution of host specifity in cuckoo bees of the genus Sphecodes (Hymenoptera)
Habermannová, Jana ; Straka, Jakub (advisor) ; Kratochvíl, Lukáš (referee)
Cuckoo bees behave similarly to the well-known birds, cuckoos - they lay eggs in the nests of other bees. Proposed thesis charts the evolution of host specialization within the strictly cuckoo genus Sphecodes. According to the classical view based on the Red Queen hypothesis, parasites should gradually specialize during evolution to keep pace in the "arms race" with their hosts. Specialization is also perceived as an evolutionary dead end - narrow adaptation prevents change of host. To test these hypotheses phylogeny of tribus Sphecodini based on the partial sequences of five genes was constructed. For each ancestor has been by two methods of mapping ancestral characters (Bayesian method, Maximum Parsimony) specified, whether it was specialist or generalist and which kind of host or hosts it had. The results show that the original strategy of genus Sphecodes is specialization and generalists originated from specialized ancestors only recently. The results also show that the jumps between the hosts are common. These findings are inconsistent with the Red Queen hypothesis as well as with the view that specialization is an evolutionary dead end. Falsity of these hypotheses within the genus Sphecodes established also likelihood ratio test, in which the likelihood of model allowing two-way transition...
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Host specificity of Large Blue (Phengaris arion) on Myrmica ants and its relation to habitat management in Valachia, east Czech Republic
REJMAN, Adam
Large Blue butterfly (Phengaris arion) is one of the critically endangered species in Czech Republic and Europe. Its larvae spend only a short part of the life feeding on flower buds, the rest of the stage it live inside ant nests and feeds on ant broods. I studied preferences of the solely host ant genus Myrmica in Wallachia (eastern Czech Republic), where the butterfly is still abundant. At this sites I explored nests the ants in the time of full grown larvae and pupae (unfortunately I did not find any butterfly stadium), recorded environmental characteristics of the nest vicinity and sampled workers of the ants for further determination. Except some marginal effects I did not find a clear differences in the niche of individual ant species.
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