Taxonomic description curves of major lineages are influenced by biological and societal factors

Taxonomic description curves illustrate how the rate of new species descriptions changes over time. Their variability and overall shape are influenced by both biological properties and societal factors. Nevertheless, these curves are often used to estimate the total diversity of taxonomic groups. We extracted description dates for all major lineages of eukaryotic life from the LifeGate project, a comprehensive repository of phylogenetic information, to construct taxonomic description curves. Half-normal distributions were fitted to the empirical data to estimate the time required to reach 10% of current diversity, the total estimated diversity, and the residuals between empirical and fitted data. To investigate the determinants of variability in curve shapes, we compiled data on body size, soil-dwelling or endoparasitic life habits, aquatic versus terrestrial habitat, geographical distribution, author numbers, and public interest for the different taxonomic groups. Using a structural equation model, we linked variability in taxonomic description curves to major factors affecting discovery rates. We show that body size, author numbers, and, to a lesser extent, geographical range and preferred habitat, influence the shape of description curves, in addition to unique historical events. Our results caution against common approaches to diversity estimation, suggesting that this goal might be better achieved through simulations or by incorporating species distributions, rather than relying on description curves alone.