 The approach using environmental pattern for such calculations can be generalised to cover other patterns to make inferences about underlying units. For PD, the pattern is phylogeny and a species’ complementarity reflects the relative number of additional features contributed by that species. PD decision-making sometimes uses calculations that are integrated with species’ estimated extinction probabilities—extending the idea of complementarity to “expected” loss. Priorities for conservation efforts for endangered species then can respond both to degree of threat and to amount of potential loss of PD. One such conservation program is the EDGE of Existence program (“evolutionarily distinct and globally endangered”; see the link in  Other Internet Resources).