In this book, four models of two interacting species and one model with three interacting species are considered. The dynamics of all the models are studied within the deterministic environment and also in the presence of environmental driving forces. Stochastic models are constructed by perturbing the growth rate of each species in chapter 2 to chapter 5. However, construction of stochastic models considered in chapter 6, is based upon the demographic stochasticity at the individual level. Analytical results obtained for the deterministic as well as stochastic models are verified with the help of numerical simulations.
