Data gaps and opportunities for comparative and conservation biology

Significance Given the current species extinction rates, evidence-based policies to conserve at-risk species are urgently needed. Ultimately, the extinction of a species is determined by birth and death rates, which drive populations to increase or decline. Therefore, demographic data are essential to inform species conservation policies or to develop extinction risk assessments. Demographic information provides an indispensable bedrock for insights to tackle species sustainable management and deepens understanding of ecological and evolutionary processes. We develop a Demographic Species Knowledge Index that classifies the demographic information for 32,144 tetrapod species. We found comprehensive information on birth and survival for only 1.3% (613) of the species, and show the major potential of zoos and aquariums to significantly increase our demographic knowledge. Biodiversity loss is a major challenge. Over the past century, the average rate of vertebrate extinction has been about 100-fold higher than the estimated background rate and population declines continue to increase globally. Birth and death rates determine the pace of population increase or decline, thus driving the expansion or extinction of a species. Design of species conservation policies hence depends on demographic data (e.g., for extinction risk assessments or estimation of harvesting quotas). However, an overview of the accessible data, even for better known taxa, is lacking. Here, we present the Demographic Species Knowledge Index, which classifies the available information for 32,144 (97%) of extant described mammals, birds, reptiles, and amphibians. We show that only 1.3% of the tetrapod species have comprehensive information on birth and death rates. We found no demographic measures, not even crude ones such as maximum life span or typical litter/clutch size, for 65% of threatened tetrapods. More field studies are needed; however, some progress can be made by digitalizing existing knowledge, by imputing data from related species with similar life histories, and by using information from captive populations. We show that data from zoos and aquariums in the Species360 network can significantly improve knowledge for an almost eightfold gain. Assessing the landscape of limited demographic knowledge is essential to prioritize ways to fill data gaps. Such information is urgently needed to implement management strategies to conserve at-risk taxa and to discover new unifying concepts and evolutionary relationships across thousands of tetrapod species.