Awesome or ordinary? Global diversity patterns of oribatid mites

Diversity of most above‐ground organisms increases with decreasing latitude, but the biogeographical and macroecological diversity patterns of below‐ground animals have been poorly studied. We investigated the latitudinal diversity gradient in a primarily below‐ground living soil taxon, oribatid mites. Furthermore, oribatid mite species richness from islands and mainlainds was tested for correlation with the size of the respective area (island or mainland) to evaluate if their species–area relationships are similar to those of above‐ground taxa. The results suggest that for oribatid mites 1) diversity increases from the boreal to the warm temperate region but not further to the tropics, and 2) species–area relationships for islands and mainlands are similar to those of above‐ground taxa, but this is mainly caused by very small islands, such as Cocos islands, and very large islands, such as Madagascar. When these islands are excluded the species–area relationship strongly differs from those of typical islands. The results support the view that below‐ground animal taxa are generalists that inhabit wide niches. Most small islands have relatively rich oribatid mite faunas, supporting the observation that a large number of species can coexist in a small area (high α‐diversity).