Ecologists have depicted the evolution of biosystems by means of system stability theory for years, such a way, however, is not able to explain the difference between evolution and adaptation of a biological species. Evolution processes, as a special manner of adaptation, is understood as an irreversible process. How to identify the irreversible processes is explored in this paper. As the examined goal, the energy growth rates of components in a biosystem form a tensor field. If each component of the tensor has no functional relation with its gauges, the tensor field is reversible, which implies that the species may restore its original growth pattern after external interference vanishes. Thereby we can obtain the criterion of a biosystem keeping species stability without any essential change. A case analysis in the context, as the demonstration, explains this hypothesis.