Data from: Cryptic species are widespread across vertebrates

Many species initially based on morphological data contain two or more cryptic species based on molecular data. These cryptic species have important implications for ecology, evolution, and conservation. For example, morphology-based species that are not of conservation concern can contain cryptic species that are in imminent danger of extinction. Here, we examined the prevalence of cryptic species across vertebrates. We also examined whether mitochondrial data overestimate or underestimate cryptic species numbers relative to nuclear data. We obtained molecular estimates of species limits from hundreds of studies across vertebrates. We found that each morphology-based species contained ~2 cryptic species on average. This number was surprisingly similar across major groups despite dramatic differences in ecology and physiology (fishes vs. birds), and was similar to comparable estimates in insects. Numbers of cryptic species estimated from mitochondrial data alone were often higher than from nuclear data, but were generally not statistically different. Overall, our results show that cryptic species are numerous and widespread across vertebrates. These results suggest that cryptic species should not be ignored in analyses of species richness, speciation, and extinction in living and fossil organisms. Furthermore, testing for cryptic species across morphology-based vertebrate species should be an urgent priority for conservation.