Conservation Units and Preserving Diversity

Abstract

Abstract A major theme in conservation biology is the preservation of diversity. An aspect of this problem that has received considerable attention is how to prioritize conservation of biological diversity below the species level. Many species are subdivided into populations that vary with respect to their genetic or phenotypic characteristics or the habitats they occupy. The taxonomy of some species groups may also be uncertain or out of date, which means that named subspecies and even species may be poor indicators of biological diversity. This diversity and uncertainty poses a challenge for conservation biologists, because a logical first step toward in conservation is describing what is available to be conserved. To address the problem of categorizing intraspecific diversity, Ryder (1986) first developed the concept of an “Evolutionarily Significant Unit” (ESU), which he defined as a taxonomic unit below the species level that captures a major component of the diversity within the species. Since then, there have been numerous attempts to define ESUs, or other conservation units, more precisely. A representative selection of these concepts is summarized below.