Life history strategies and sexual dimorphism of the Amphibia with special emphasis on the Urodela (Newts and Salamanders) and the Gymnophiona (Caecilians)
This thesis deals with the reproductive biology of newts and salamanders as well as with caecilian amphibians and focuses on the evolution of their life history strategies, especially parental investment and sexual dimorphism. One salamander and two caecilian species were studied using laboratory populations in search for hitherto unknown reproductive behaviours or to clarify earlier findings. In the course of this study, new and unexpected insights into the life history strategies of these species were gained. Collection-based research using large samples of museum specimens, histology, skeletochronology and synchrotron-based x-ray studies completed the approach. Life history traits, such as the mode of reproduction or the type of parental care, are more or less mutually dependent with other factors like environmental conditions, behaviour or morphology. The evolution of parental care strategies and sexual dimorphism are crucial to understand the evolutionary framework of life histories and mating systems. This thesis shows how divergent selective pressures and behavioural strategies can influence the phenotype of the genders in connection with their reproductive roles and within different habitats as well as evolutionary changes and adaptations of different reproductive modes.