Back to: Projects

Biodiversity and WorldMap

Relationship among estimates of biodiversity value:
a scale of surrogacy for mapping more at lower cost 


If greater biodiversity value is associated with richness in a currency of expressible genes (or the characters of organisms for which they code), then when resources for sampling are limited, higher levels of biological organisation (or of the environmental factors affecting its distribution) will have to be employed for more practical surrogate measures (the term assemblages is used here for non-monophyletic groups of organisms, although it is debatable whether ecosystems, if defined in terms of processes, can be mapped and counted). Choosing a surrogacy level from this scale is a compromise between precision of the measure on the one hand, and availability of data and cost of data acquisition on the other (ref 4) (below):

Choosing surrogates to use in measuring biodiversity value

precision as a measure of character diversity

A scale of surrogacy for a value currency of character diversity

inexpensive surveys and  
units more inclusive of  
viability enhancing processes

low ECOSYSTEM richness high
environmental surrogates climate class richness
terrain class richness
substrate class richness
environmental / assemblage  
landscape class richness
habitat class richness
assemblage surrogates 'community' class richness
vegetation class richness
taxonomic surrogates higher taxon richness
SPECIES / subspecies richness
taxonomic/phylogenetic subtree richness
high GENE / character richness (currency) low

Many of these relationships remain very poorly understood, so that they must be used with due care for establishing supporting evidence from test samples.

A consequence of this approach to valuing biodiversity is that it provides one possible unified view of the traditional three levels at which biodiversity has been described. In effect it uses genetic diversity as a basis for valuing both species diversity (for their relative richness in different genes) and ecosystem diversity (for the relative richness in the different processes to which the genes ultimately contribute).