Das Modell der Einführung und Einbürgerung nicht einheimischer Arten.Ein Beitrag zur Diskussion über die Freisetzung gentechnisch veränderter Kulturpflanzen

As soon as transgenic cultigens are released into the environment they may become feral as we know of many conventional cultigens. This article explains two basic ways how cultigens become feral: through hybridization with closely related wild plants or through revert to the wild-type. Some aspects of the evolution of cultigens are discussed since they are the key to understanding the current processes of becoming feral. A list of many examples of conventional cultigens becoming feral in Central Europe is presented. Due to a virtually complete lack of information on the ecological behaviour of transgenic cultigens the authors suggest two different models to predict the ecological risks of transgenic cultigens, particularly the probability of becoming feral and moreover the probability of undesired ecological long-term effects in man-made ecosystems as well as in semi-natural and natural ecosystems. If we like to make a prognosis about a single, precisely characterized, transgenic cultigen it makes sense to compare it directly to the original plant that was conventionally bred and that we are familiar with. In a so-called "case by case study" a single conventional cultigen functions as a model for a single transgenic cultigen and answers the questions, what is the probability of a single transgenic cultigen becoming feral and what are possible undesired ecological effects of this process particularly in man-made ecosystems. However, if we like to predict undesired ecological long-term effects in semi-natural and natural ecosystems we suggest to compare the process of becoming feral in general to the introduction and naturalization of non-native species ("Exotic Species Model"). The intended or unintended introduction of non-native species by man and the subsequent naturalization of a proportion of these species functions as an appropriate and valuable model of the long-term ecological behaviour of both transgenic and conventional cultigens that have escaped cultivation and invaded semi-natural and natural ecosystems. The implications of the two models are discussed in detail.