Conserving organisms over large regions requires multi-taxa indicators: One taxon’s diversity-vacant area is another taxon’s diversity zone

There is an increasing use of indicator taxa to predict spatial patterns in other taxa, yet it is unclear how well species from one taxonomic group may serve as indicators of species richness in other groups with different ecological needs. We analysed spatial patterns of diversity in several arthropod taxa from the Turkish fauna (Scorpiones, Chilopoda, Coleoptera Cicindelidae, Hydrophilidae (gen. Laccobius), Nitidulidae, Tenebrionidae Pimeliini, Chrysomelidae Cryptocephalinae, and Lepidoptera Hesperioidea and Papilionoidea) to test whether there are multi-group hotspots or whether different groups have different areas of maximum diversification. We used three metrics of diversity: species richness, residuals from the species–area relationship, and species/area ratios. In each group, the three metrics were significantly positively correlated. However, the hotspots identified using one metric show small agreement with those identified by other metrics. Although patterns of cross-taxon diversity were significantly and positively correlated for all metrics, hotspots of different groups show little overlap. Moreover, proportions of non-target species captured by hotspots of a target taxon were usually moderate. On the other hand, we found that hotspots of certain groups tend to be concentrated in particular regions, and some groups were good surrogates for others. The Mediterranean and Central and Eastern Anatolian ecogeographic regions included hotspots of species richness for most taxa. Using the species/area ratios, all groups had at least one hotspot in the Marmara and Eastern Black Sea regions, and most groups also in the Mediterranean and Eastern Anatolian regions. Hotspots identified using the residuals from the species–area relationship are concentrated mostly in the Eastern and Central Anatolian regions. These results are explained with reference to the historical biogeography of the study area, the ecological needs of the different taxa and compared with the distribution of National Parks. For an effective conservation approach, we advocate the use of subsets of species as surrogates for all species, provided that selected subsets are representative of animals with different ecological needs and biogeographical histories.