Thesis (Ph. D.)--University of Illinois, 1918. / Vita. Bibliography: p. 113-118.

Thesis (Ph. D.)--University of Illinois, 1918. / Vita. Bibliography: p. 113-118.

Texte remanié de: Dissertation--Augsburg--Universität, 2006. / Bibliogr. p. 337-343.

Proefschrift - Leiden.

Th. doct.--Lettres--Paris III--Université de la Sorbonne nouvelle, 1994. / Bibliogr. p. 486-555. Index.

Proefschrift - Leiden.

Tadpoles are known to behaviorally respond to visual, auditory or chemical cues. I examined the influence of group size and light conditions on the activity of Phyllobates vittatus. I performed laboratory experiments to measure locomotor activity. Activity levels of tadpoles were higher in the groups. Light conditions did not influence activity level of tadpoles. My results suggest that the group size is one of the main factors influencing tadpole locomotor activity of Phyllobates vittatus.

The increasing level of the UV-B irradiation due to depleting of the ozone layer is considered to be one of the causes of global amphibian declines. The UV-B radiation causes damage to the DNA in the nuclei of the skin cells and their eventual death. In many amphibian species there was found a negative influence of the UV-B radiation on the hatching success of tadpoles and their subsequent viability. It has been assumed that tadpoles are able to actively avoid places with the higher exposure of the UV-B radiation thanks to their locomotion. In this experiment tadpoles could have chosen between a zone with the UV radiation (UV-B and UV-A) and without the UV radiation. The tadpoles have not been exposed to the UV radiation before the measurement started. The location of the tadpoles during the measurement was recorded by CCD camera. A computer program EthoVision then evaluated the time that these tadpoles spent in each of the zones and the total path length these tadpoles has swum in the zones. The measurements were performed for two groups of tadpoles differing in age to determine whether the level of development may affect the tadpoles' preference to the UV radiation. The tadpoles in both groups spent more time in the zone without the UV radiation. The tadpoles in the more advanced development phase have spent 7 times more time in average in the zone without the UV radiation than in the zone with it. The tadpoles from the second group have spent in average 2.5 times more time in the zone without the UV radiation than in the zone with the UV radiation. The total swimming path length of advanced tadpoles was almost 2.5 times longer in the zone without the UV radiation than in the zone with the UV radiation. Conversely, the total path length of younger tadpoles did not significantly differ between the zones. The total time spent in the zones with / without the UV radiation did not differ between the groups of tadpoles. Also the total path length did not differ between the groups in the zone with the UV-B radiation. However, the total path length of tadpoles had differed between groups in the zone without the UV radiation.

Predation and prey responses to predators in aquatic environment are reviewed with emphasis on non-lethal effect of predators on prey life history, antipredator behavior and related mechanisms. The review focuses on dragonfly larvae and other groups of prey with complex life histories, mainly anurans. The review is complemented by laboratory experiments examining the effects of varied food availability and predation risk on a selected species of dragonfly, Sympetrum vulgatum.

An increasing amount of attention is devoted to studying the impact of non-native animal species on native species. Among other causes of ecosystem degradation, such as climate change, polution and habitat conversion, biological invasion is considered as one of the main causes of the decrease in biological diversity all over the world. In order to detect possible predation event, tadpoles use not only visual and mechanical stimuli, but also chemical one. The tadpoles respond to the certain chemicals to be a part of predator's secretions. In aquatic systems, chemical cues are a major source of information through which animals are able to assess the current state of their environment to gain information about local predation risk. Prey use chemicals released by predators to mediate a range of behavioural, morphological and life-history antipredator defences. Tadpoles swim significatnly less and also on a less direct trajectory in the presence of chemical cues released by a turtle Trachemys scripta. This article is focused on the influence of mentioned constraints on the dynamics and the time dynamics of the larval growth of Rana temporaria. The influence was judged by the impact on the tadpole's development. We anticipated a behavioral response to the predator, which would lead to various growth reactions during larval growth, the resulting body size after metamorphosis, but also in the development time of larval stage. The results indicate that tadpoles of Rana temporaria changed behaviour in the presence of Trachemys scripta. Tadpoles in the permanent presence of the turtle grew faster, metamorphosed earlier and the resulting size after metamorphosis was smaller than of the tadpoles who developed without presence of the predator. Mentioned reactions may affect the survival and fitness of a metamorphosed individual.