We describe a stochastic method for tracing the evolutionary pattern of multialigned sequences. This method allows us to detect gene regions with distinct evolutionary dynamics, e.g., regions that significantly deviate from the expected behavior. Accurate detection of hypervariable or hyperconstrained regions may provide useful information on the structure/function relationship of biosequences. This information can help localize functional constraints. In addition, the selection of distinct evolutionary dynamics may assist in the correct use of biosequences as reliable molecular clocks.