In this paper we introduce the notion of Population-based Adaptive Systems (PAS)with 3-tier adaptation by evolutionary, individual, and social learning (EL, IL, SL).We discuss some important aspects of using combinations of these adaptivemechanisms in general. We pay special attention to using natural reproductionin EL and the consequences of this for EL+IL combinations. We also presentdetails on the NEW TIES system, partly as a running example, partly forits own sake as a concrete realisation of a 3-tier PAS that is available asa research platfrom for experimental studies.