Individual and population level dynamics of Daphnia at varying conditions of food, temperature and fish predation: a model approach

摘要

For many ecologists models are attractive tools because they allow the investigation of complex systems where several processes interact. The overall effect of these processes and the contribution of each single process can not easily be estimated - at least a priori — on basis of direct laboratory measurements. Model studies on growth and reproduction of Daphnia, a key species in many lake food webs, provide a promising example how model approaches can be successfully applied to get more insight into the underlying physiological processes (e.g. energy acquisition, maintenance costs). In recent decades, substantial progress was achieved by applying bioenergetic models to simulate somatic growth and reproduction. Such approaches were based on energy allocation rules describing the allocation of assimilated energy (or carbon) to distinct processes like maintenance, somatic growth and egg production (Kooijman Metz 1984, Gurney et al. 1990). However, existing models are restricted to a constant temperature (20℃) and do not include validation of model outputs with experimental data for a range of food concentrations. This gap is bridged by the presented model approach based on energy allocation rules that, in contrast with previous model approaches, incorporates variable temperature and rigorous model validation of data from a life-table experiment. Moreover, we integrated our individual-level model into a stage-structured population model in order to allow its application on the population level.