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

	Advantage:   precision as a measure of character diversity	A scale of surrogacy for a value currency of character diversity	Advantage:   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   surrogates		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).