Beyond surrogacy: A multi-taxon approach to conservation biogeography

Biogeographic analysis of species turnover (β diversity) of plants and animals among regions often yields conflicting results, with regions of high β diversity identified for some taxonomic groups but not others. Such discordance calls into question use of surrogate taxa to forge conservation plans. This discordance begs for a means of comparing multiple taxa across phyla in a manner that is cost-effective, considers limitations in computer resources in certain global regions, and is understood by policy makers and land managers. As a test case for a method taking into account these considerations, we used species lists for ten organismal groups (spanning plants, vertebrates, and invertebrates) to identify regions of high β diversity using Monmonier’s algorithm, a spatially explicit technique that is readily implemented and interpreted. Data were for montane (>1000 m elevation) species across the Eastern Arc of Tanzania and Kenya and surrounding areas. Our results indicate that surrogacy does not make for the most effective expenditure of conservation efforts. We also show that to use a multi-taxon approach one need not to rely on intensive surveys of areas in order to make conservation decisions, including reserve selection. Our approach also eliminates the need for complex modeling and comparisons common to many GIS-based complementarity techniques. Additionally, a wide variety of socioeconomic, political, demographic, geological, climatological, and evolutionary factors can be incorporated into the technique to help shape conservation biogeography from a local and regional perspective. This technique can bridge the gap between conservation biogeography theory and application in tropical regions and beyond.