The number of mammal and bird species varies from place to place, but these groups of vertebrates still span much of the world. Reptiles do not. New research shows they are highly concentrated in hotspots and are largely absent across the rest of the earth (blue map). This highly uneven dispersion (brown maps) is a surprise. Scientists had diagrammed the somewhat smooth distributions of other tetrapods—vertebrates descended from the earliest four-limbed creatures. Those populations are typically large in extended regions and gradually tail off in many directions. The experts assumed that reptiles followed a similar pattern and designed conservation measures on the same false assumption. Now that investigators actually know where the world's 10,000 reptile species are, says Shai Meiri of Tel Aviv University, a member of the study team, “we can better model the threats to these species, so we know where to invest, to best protect all of nature.”

Credit: Mapping Specialists (maps); Rachel Ivanyi (illustration); Source: “The Global Distribution of Tetrapods Reveals a Need for a Targeted Reptile Conservation,” by Uri Roll et al., in Nature Ecology & Evolution, Vol. 1; November 2017