Based on questions about proximate causes and ultimate and historical conditionality for structural features, we can distinguish developmental morphology, functional morphology, evolutionary morphology, and phylogenetic morphology. Evolutionary morphology focuses on the biological roles and the selective values of structures as inferred from direct observation or by analogy. Based on detailed comparative analyses of structures, the field of evolutionary ecology is opened up. The objective of evolutionary ecology is to reconstruct the historical formation of specific ecological niches and the establishment of ecological zones. In-depth investigations of the ecological niches of extant species allow to reconstruct the ecological niche of any stem species at a point of bifurcation in a cladogram. It is further possible to outline the transformation of the ancestral econiche by change, formation or dissolution of synergs which compose the econiche. Thus, the sequence of econiches can be reconstructed, at least in significant dimensions of the relationship between the organism and its environment (synergs). One example is the sequence of econiches in fungus-growing ants (Attini), which initially used insect feces as fungal substrate, then petals, and finally sections of leaves. To realize an econiche, the interactions of organisms with their environment are essential, as well as collaborative activities of conspecifies. The econiche of a species often consists of different, mostly chronological sub-niches, represented by different morphs. Typical examples are larvae (characterized by larval features) and their sub-niches, separated from the adults and their sub-niches by metamorphosis. Substantial evolutionary changes of a niche can happen in a few steps if many synergs are clustered (for instance during the switch to a novel host), or if sub-niches of ontogenetic stages are abandoned (e.g. by evolution of vivipary). Behavioral alterations which broaden or change the econiche precede the dramatic rearrangement of the mode of life during realization of a new ecological zone. The link between the formation of a new ecozone and "macroevolution" is exemplified by the evolution of Pterygota, taking into consideration ecological licenses, preadaptations, alterations of behavior and evolutionary adaptations. The sequence of ecozones during the evolution of a terrestrial true bug towards Gerridae living on the water surface of open oceans is presented, as well as the sequence of ecozones of terrestrial case-building moths towards aquatic caterpillars which feed on algae even in rapidly flowing streams. Six steps of the evolutionary ecology approach towards an explanatory natural history are compiled.
