Advances in geoprocessing and satellite imagery have boosted our knowledge of the Earth’s physical environment, but many pieces of the Earth’s biodiversity puzzle are still lacking. Conservative estimates indicate that we only know 13 to 18% of all living species of the planet. Mapping the missing pieces of this puzzle can help scientists and decision makers to identify where on Earth to prioritize discovery and conservation. We used data on biological and environmental attributes of species in a survival model framework to estimate the discovery probability of amphibian and reptile species across time. Specifically, we predicted three discovery metrics across space: (i) percentage and (ii) number of undescribed species, and to calculate the (iii) number of years needed to complete amphibian and reptile discoveries. We applied our model framework to calibration datasets that included species described within different time-periods, from 1758 to each decade from 1800 to 2010. We then compared the estimated number of undescribed species obtained for each time-period against the observed number of discoveries after each decade, from 1800 to 2010.
Results/Conclusions
We find that more recent species descriptions are associated with narrow geographic range size, small body size, regions with higher human population density, and a greater number of taxonomists. Our models make specific spatial predictions for the most rewarding regions for future species discovery. For amphibians, these include Neotropical moist broadleaf forests, followed by Indomalayan dry broadleaf forests. New reptile species are expected in Neotropical coniferous forests, and in dry broadleaf forests and savannas in the Afrotropics. We predict about 1/3 more reptile than amphibian species left to be discovered. Applying a validation correction to our absolute predictions suggest that as many as 4,000 amphibian and 6,000 reptile species may yet to be described. These findings reveal that our ignorance on the diversity of terrestrial vertebrates can be far higher than previously thought, with potentially around half of herptile species yet to be described. With ongoing global change, a boost to the discovery of unknown species is critical for ensuring a responsible management of our planet.