Ph. Williams et al., MAPPING BIODIVERSITY VALUE WORLDWIDE - COMBINING HIGHER-TAXON RICHNESS FROM DIFFERENT GROUPS, Proceedings - Royal Society. Biological Sciences, 264(1378), 1997, pp. 141-148
Maps of large-scale biodiversity are urgently needed to guide conserva
tion, and yet complete enumeration of organisms is impractical at pres
ent. One indirect approach is to measure richness at higher taxonomic
ranks, such as families. The difficulty is how to combine information
from different groups on numbers of higher taxa when these taxa may in
effect have been defined in different ways, particularly for more dis
tantly related major groups. In this paper, the regional family richne
ss of terrestrial and freshwater seed plants, amphibians, reptiles and
mammals is mapped worldwide by combining: (i) absolute family richnes
s; (ii) proportional family richness; and (iii) proportional family ri
chness weighted for the total species richness in each major group. Th
e assumptions of the three methods and their effects on the results ar
e discussed, although for these data the broad pattern is surprisingly
robust with respect to the method of combination. Scores from each of
the methods of combining families are used to rank the top five richn
ess hotspots and complementary areas, and hotspots of endemism are map
ped by unweighted combination of range size rarity scores.