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Growth and sexual selection in selected representatives of scarabaeoid beetles (Coleoptera: Scarabaeoidea).
Vendl, Tomáš ; Šípek, Petr (advisor) ; Knapp, Michal (referee) ; Skuhrovec, Jiří (referee)
Flower chafers are well-known beetles with apparent sexual dimorphism. Yet, in contrast to other groups of scarab beetles, only little attention has been paid to various aspects of this phenomenon. It concerns also sexual dimorphism in size, which is very common in animals. Although ultimate causes of sexual size dimorphism have been extensively studied, the developmental mechanisms are still only poorly understood. We investigated proximate causes of sexual size dimorphism in several differentially dimorphic flower chafer species. We found that in highly dimorphic species the dimorphism started to develop already in the first instar and tended to accumulate through successive larval development. In contrast, the sexes in species with a relatively low dimorphism diverged in size during only one instar. Moreover, we found variability not only in when the dimorphism arises during development, but also how: sex-related differences in both the instar duration and average growth rate were the proximate causes of sexual size dimorphism. In addition, we showed that the sexes may differ also in growth trajectory - males had relatively longer period of rapid growth than females, even in cases where the absolute development times were similar in both sexes. Further, we focused on systematic survey of sexual...
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Growth and sexual selection in selected representatives of scarabaeoid beetles (Coleoptera: Scarabaeoidea).
Vendl, Tomáš ; Šípek, Petr (advisor) ; Knapp, Michal (referee) ; Skuhrovec, Jiří (referee)
Flower chafers are well-known beetles with apparent sexual dimorphism. Yet, in contrast to other groups of scarab beetles, only little attention has been paid to various aspects of this phenomenon. It concerns also sexual dimorphism in size, which is very common in animals. Although ultimate causes of sexual size dimorphism have been extensively studied, the developmental mechanisms are still only poorly understood. We investigated proximate causes of sexual size dimorphism in several differentially dimorphic flower chafer species. We found that in highly dimorphic species the dimorphism started to develop already in the first instar and tended to accumulate through successive larval development. In contrast, the sexes in species with a relatively low dimorphism diverged in size during only one instar. Moreover, we found variability not only in when the dimorphism arises during development, but also how: sex-related differences in both the instar duration and average growth rate were the proximate causes of sexual size dimorphism. In addition, we showed that the sexes may differ also in growth trajectory - males had relatively longer period of rapid growth than females, even in cases where the absolute development times were similar in both sexes. Further, we focused on systematic survey of sexual...
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Influence of military disturbances on succession of arthropod communities in Brdy
Palivcová, Lucie ; Tropek, Robert (advisor) ; Knapp, Michal (referee)
The thesis aims for relationship between military-caused disturbance intensity and species richness, conservation value and composition of arthropods communities in the Brdy Mts. In the Brdy abandoned military area (MTA), a highly heterogeneous habitat mosaic developed by the long-term influence of military disturbances on two shooting areas of Jordán and Tok. The habitats range from strongly disturbed sites with sparse vegetation, through heterogeneous growths of Erica and Vaccinium in moderately disturbed sites, to sparse woodlands in the least disturbed sites. Based on the shooting areas history reconstruction, 24 study plots of 4 categories of different disturbance intensity were selected in both shooting areas together. Standardized sampling of seven groups of arthropods was performed in summer 2017 by pitfall traps, yellow pan traps, and light traps. More intensive disturbances positively influenced species richness of Aculeates and conservation value of spiders and beetles, but negatively affected species richness of moths. Simultaneously, the intensity of disturbances affected community composition of spiders, moths, beetles, Aculeates and Orthopteroids. Endangered species mostly affiliated to the more intensively disturbed plots. This results should be helpful in understanding of influence...
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Temporal variability in spatial distribution of carabid beetles in agricultural landscapes
Seidl, Miroslav ; Knapp, Michal (advisor) ; Harabiš, Filip (referee)
The aim of this thesis is to work out a brief literary research focused on spatial distribution of carabid beetles (Coleoptera, Carabidae) around arable field-woodland boundaries throughout the season. Substantial part of this thesis consistsof thefield experiment aiming to explore given issue in the model area near Sedlčany. Carabid beetles were collected employing pitfall traps along four transects perpendicular to arable field-woodlot boundaries. Beetles were sampled during five sampling periods, but only four complete (undamaged) temporal samples series were used for final statistical analyses:1) early spring, 2) late spring, 3) summer and 4) late autumn.Three species groups were identified according to their habitat specialization:1) open habitat specialists, 2) habitat generalists and 3) forest specialists; and these groups were analysed seperately.
Total species diversity was highest in area of ecotone between arable field and woodlot.The edge between habitats was preferred by habitat generalist species and open habitat specialist species also spilled over here. Distribution of relative species richness and relative activity density was not stable in time. Spatial distribution of forest species was relatively less variable. Open habitat species aggregated within habitat boundaries instead of field interiors in early spring, probably as a result of overwinteringbehaviour. Generalists were also aggregated in the edge between habitats in autumn period and during early spring occurred relatively more in the centre of woodlot than in other periods. Species composition of carabid beetles assemblages depended partly on season and also on position of transect. There was also a significant interaction between spatial and temporal variability in species composition of carabid assemblages. Woodlot assemblages seem to be less variable in time.
The results of this thesis contribute to extension of knowledges on distribution of carabid beetles in agroecosystems, where many carabids act aspredators of various pests. The biggest changes in spatiotemporal distribution of carabid beetles in agricultural landscape could be linked with preference of adults to overwinter out of arable land.
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