Habitat templets are graphical-qualitative models which describe the development of life-history strategies in specific environmental conditions. In the context of the previous models of life-history strategies, life-history theorists focused on the density-dependent factors as the factors determining life-history strategies. With the use of habitat templets, the focus is oriented towards the environmental causal factors, considering density-dependent phenomena as by-products of the environmental impact. This implies an important shift in causality as well as in the worldview of life-history theorists: population is (...) not considered as a closed system isolated from the environment. The object of study is the organism-in-its-environment, as a complex multilevel system. This shift has also methodological consequences: Life-history theory combines holistic and reductionistic insights, using a variety of heuristic models. This imposes a new conception of generality as well as of the structure of scientific theories. (shrink)