Conservation genetics at the species boundary

Conservative genetics has expanded its purview such that molecular techniqu es are now used routinely to prioritize populations for listing and protect ion and infer their historical relationships in addition to addressing more traditional questions of heterozygosity and inbreeding depression. Failure to specify whether molecular data are being used for diagnosis-related que stions or for population viability questions, however can lead either to mi sinterpretation of character data as adaptive information or to misinterpre tation of frequency or distance data as diagnostic or historical informatio n. Each of these misinterpretations will confound conservation programs. Th e character-based approach to delimiting phylogenetic species is both opera tionally and logically superior to "diagnostic" methods that involve distan ce- or frequency-based routines, which are unstable over time. Tree-based c riteria for the diagnosis of conservation "units" are also inappropriate be cause they can depend on patterns inferred without reference to diagnostic characters. Intraspecific studies, conservation-related or otherwise, that adopt terminology and methods designed to infer nested hierarchic relations hips confuse diagnosis with historical inferences by treating diagnosis as outcomes rather than as precursors to phylogeny reconstruction. A character -based diagnostic approach recognizes the analytical dichotomy between spec ies hierarchies and population statistics and provided a framework for the understanding of each. No species concept, however, should be viewed as an absolute criterion for protecting populations, but as part of a framework f rom within which identification of protection and management goals can be a chieved effectively and defensibly.