What would be the impact of an environment change on the persistence and the genetic/phenotypic distribution of a population? We present some integro-differential models describing the evolutionary adaptation of asexual phenotypically structured populations subject to mutation and selection in changing environments. Using an approach based on Hamilton-Jacobi equations, we provide an asymptotic analysis of such equations in the regime of small mutational variance. This analysis allows us to characterize different evolutionary outcomes depending on the type of the environmental change.