Biodiversity, Taxonomic Relatedness, and Endemism in Conservation

Abstract Practical approaches to measuring biodiversity are described. Within any defined geographical area biodiversity is considered to be a measure of two main variables: number of taxa and degrees of difference between taxa. Three approaches for the measurement of biodiversity are described, phenetic, phylogenetic, and cladistic, the latter being considered the most appropriate. Using the computer program WORLDMAP comparative trials of four different measures of cladistic diversity, root-weight, higher taxon richness, spanning-tree length, and cladistic dispersion, were undertaken. Even representation of sub-groups within taxa using the cladistic dispersion measure agrees best with the popular, intuitive ideal of what consititutes the most diverse fauna or flora. The taxonomic measures were used together with a measure of end emism in conjunction with complementarity of floras and faunas to determine priority sequences of areas for conservation. It was concluded that the greatest contribution to the conservation and representation of biodiversity is from complementarity, but differences between organisms can be most readily represented by using available information of group membership from taxonomic classifications. Endemism is not a measure of biodiversity but of range size, and was shown to be ineffective as a means for selecting areas for conservation if not all selected areas could be included.