The role of PT phase transition in biology and ecology Dorje Brody U. Surrey In this talk I will illustrate how stochastic Schrödinger equations (SSEs) can be used effectively to describe dynamical behaviours of biological systems. In the context of biology or ecology, the Hamiltonian in the SSEs models changes of environmental conditions, while the Lindblad operator in the SSEs models adaptation. When the two operators are incompatible, the system dynamics can exhibit a phase transition associated with the changes in the eigenvalue structures of the Liouville operator. Such transitions are important in determining wether a biological system manages to adapt to the changes of the environmental conditions.