Heterarchy
A heterarchy is a system of organization where the elements of the organization are unranked (non-hierarchical) or where they possess the potential to be ranked a number of different ways. Definitions of the term vary among the disciplines: in social and information sciences, heterarchies are networks of elements in which each element shares the same "horizontal" position of power and authority, each playing a theoretically equal role. But in biological taxonomy, the requisite features of heterarchy involve, for example, a species sharing, with a species in a different family, a common ancestor which it does not share with members of its own family. This is theoretically possible under principles of "horizontal gene transfer."