Staying or leaving: Triggers of emigration

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Dispersal is an essential trait of organisms that influences stability, diversity and thus also the long-term existence of whole communities. This process of dispersal can be divided into introductory emigration, transfer to other habitats and migration in the new habitat. Dispersal is multi-causal, influenced by the characteristics of an organism and environmental factors. Previous studies have shown, that organism density, food availability and predator pressure are typical causes of emigration. These factors influence organisms at the intra- and interspecific level and, moreover, interact simultaneously with each other. The scientific challenge is not to consider the importance of influencing factors solitary, but in the overall context of the interactions. The main goal of the presented project is to investigate basic triggers for the emigration of organisms. In contrast to many previous studies, the focus here is on the interactions of various factors (organism density, food availability and predator pressure). Furthermore, for the first time, the impact of these factors on (1) single species and (2) species combinations as well as on an (3) entire community will be quantified. A series of standardized laboratory experiments ensures a high degree of comparability and informative value.The test organisms used in this study are nematodes, the most common metazoans worldwide. Because of their distribution potential, the easy and fast cultivation, the species-specific characteristics, the frequent and diverse occurrence in the field and their ecological significance nematode are optimally suitable for the project.The experiments are performed in test vessels that have been adapted to nematodes and whose usability has been proven in preceding investigations. Nematodes are placed in a starting chamber with a manipulated initial situation (for example, high density of food and the presence of a predator). Subsequently, the migration of individuals is documented after seven days. In total, three central project sections with a total of 730 single tests will be carried out over a period of two years.