Evolution of Knowledge Bases (KBs) expressed in Description Logics (DLs) proved its importance. Recent studies of the topic mostly focussed on model-based approaches (MBAs), where an evolution (of a KB) results in a set of models. For KBs expressed in tractable DLs, such as DL-Lite, it was shown that the evolution suffers from inexpressibility, i.e., the result of evolution cannot be expressed in DL-Lite. What is missing in these studies is understanding: in which DL-Lite fragments evolution can be captured, what causes the inexpressibility, which logics is sufficient to express evolution, whether and how one can approximate it in DL-Lite. This work provides some understanding of these issues for eight of MBAs which cover the case of both update and revision. We found what causes inexpressibility and in which DL-Lite fragment evolution is expressible. For the latter case we provide polynomial-time algorithms to compute evolution results. For the former case we proposed techniques (based on what we called prototypes) to capture evolution corresponding to a well-known Winslett's approach in a DL SHOIQ. We also showed how to approximate evolution of DL-Lite KBs in DL-Lite by reasoning over these SHOIQ KBs.