  The models discussed so far are continuous-time models, that is, the temporal or dynamic parameter is assumed to be a continuous variable. However, discrete-time models have also been used to study population processes. A discrete analog of the logistic growth model was one of the first systems in which chaotic dynamic phenomena were  discovered.[16]  Over the years there has been considerable debate over the question whether ecological systems with chaotic dynamics exist in nature; the current consensus is that they have not yet been  found.[17]