Evolutionary theory predicts that inter-specific hybrids and taxa with clonal or hemiclonal reproduction are at a selective disadvantage in comparison with genuine and sexually reproducing species. Yet, some of the allegedly “handicapped” organisms occupy extensive ranges, maintain large populations and have achieved longevity of more than 200'000 generations. We use the hemiclonal European water frog (Pelophylax esculentus) - originally a hybrid between the pool frog (P. lessonae) and the lake frog (P. ridibundus) - as a model system to investigate the genetic, behavioural and ecological reasons for this unexpected ecological and evolutionary success. Our investigations also shed light on a variety of other biological issues. These include the dynamics of tightly coupled systems (e.g. parasite/host), maintenance of hybrid zones, speciation, sexual conflicts and the question: how do the behavioural strategies of individuals affect the composition and dynamics of populations and communities?