Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisors: Michael C. Singer and Ulrich G. Mueller. Vita. Includes bibliographical references.

No description available.

This study aims to get a better understanding of the oviposition-behaviour of the butterflyMarsh Fritillary (Euphydryas aurinia), in the area Bälsalvret on the Island of Gotland. Thestudy may provide helpful information to aid the conservation of the species in the area andalso provide overall knowledge about the female’s preferences when it comes to choosingmicrohabitat and host plant for their eggs.The analysis of the microhabitat preference for oviposition by the Marsh Fritillary showedthat eggs were predominantly laid on large-sized host plant individuals with a warmermicroclimate; with a preference for the rosette diameter, the length and the width of the leafand the number of Succisa pratensis individuals in the vicinity. This indicates that thefemale’s priority is to place the eggs at the most optimal place for their offspring’s survivaland growth.

This study aims to get a better understanding of the oviposition-behaviour of the butterfly Marsh Fritillary (Euphydryas aurinia), in the area Bälsalvret on the Island of Gotland. The study may provide helpful information to aid the conservation of the species in the area and also provide overall knowledge about the female’s preferences when it comes to choosing microhabitat and host plant for their eggs. The analysis of the microhabitat preference for oviposition by the Marsh Fritillary showed that eggs were predominantly laid on large-sized host plant individuals with a warmer microclimate; with a preference for the rosette diameter, the length and the width of the leaf and the number of Succisa pratensis individuals in the vicinity. This indicates that the female’s priority is to place the eggs at the most optimal place for their offspring’s survival and growth.

The purpose of the study was to provide further knowledge about if the total amount of solar radiation during the marsh fritillary’s (Euphydryas aurinia) period for larvae development (April 15th – May 15th) and/or flying period (June 1st – June 30th) influenced the average of larvae colonies in the autumn at 12 sites in Dalarna County. Among increased temperatures, global climate models also predict an increased amount of solar radiation and a decrease in cloudiness in northern Europe, as a result of the climate changes. The marsh fritillary has declined rapidly, especially in the Northern of Europe and are in Sweden red-listed as vulnerable (VU). The marsh fritillary is a univoltine species who are dependent on open, sunny, and moist semi-natural grasslands with the hostplant devil’s bit (Succisa pratensis). The data over solar radiation was received from SMHI and had been measured in Borlänge over the last 14 years. The data over the number of larvae colonies was received from Länsstyrelsen Dalarna and had been measured over the last 15 years. The linear regression analysis for both the period of larvae development (p=0,58) and the whole period (p=0,07) indicates that during those periods the solar radiation did not influence the average of larvae colonies. However, the total amount of solar radiation during the flying period (p=0,02) influence the average of larvae colonies during the autumn.

Herbivory is one of most important factors which form meadow ecosystems. These ecological communities have one of the biggest variety of species in Central Europe and their research is important in terms of management of protected species as well. Localities which has a similar importance, is also a meadow ecosystem with occurrence of Succisa pratensis, the only host plant for rare butterfly Euphydryas aurinia. Research of Succisa and its other herbivores can improve a protection of this particular butterfly. Effects of herbivores of Succisa were examined by several experiments. The first one was a field cage experiment. Its aim was to detect what kinds of herbivores (rodents and invertebrates) are involved in herbivory of leaf rosettes of Succisa and what is their impact on the fitness of these plants. The intensity of herbivory of Succisa was measured for over two vegetation seasons on the month bases. In this experiment were also examined effects of surrounding vegetation on the studied plants of Succisa. The second experiment was performed in a garden. Its aim was to clarify the role of herbivores of leaf rosettes, stalks and their interactions on the fitness of Succisa. The third experiment was concerned to true bugs, which are pre-dispersal predators of seeds of Succisa. Their effects on...

In present thesis, I treat the topic of impacts of plant-animal interactions, namely herbivory and pollination, on plant life cycle and lifetime fitness. First, I identify the components of the impact of plant-animal interactions: i) interaction frequency; ii) per-interaction effect; iii) sensitivity of the plant's life cycle to the changes in vital rate impacted by the animals. Furthermore, I also classify other causes changing the outcome of a plant-animal interaction into two categories: i) plant's traits; ii) plant's environment. A review of extant literature on the topic revealed that especially the role of plant's environment in changing the outcome of plant-animal interactions is largely understudied and I attempt to reduce this gap in knowledge in the five detailed studies encompassed in this thesis. The detailed studies focus on a model system of Central European wet grasslands and especially on three species typical to it: Succisa pratensis, Achillea millefolium and A. ptarmica. The first two studies examine the effects of environment on frequency of plant- animal interactions. The next two studies are more integrative, one focusing on the impacts of different herbivore groups on the complete life cycle and the other on interaction of herbivory and pollination on plant lifetime fitness....