Abstract: The number of species in a taxonomic group that inhabits a given region is one of the most simple, yet fundamental pieces of information needed for many practical and theoretical reasons. However, an answer to the question of how many species there are has proven to be elusive and even controversial for many groups. In this talk I describe the temporal dynamics of species discovery (based on species descriptions or first records) and the resulting species-accumulation curves for the fishes of the Eastern Tropical Pacific, the Greater Caribbean and the Red Sea. Comparisons of the results obtained for these tropical regional fish faunas reveal several generalities. For instance, in none of the regions is the species accumulation curve decelerating during the last century, clearly indicating that regional faunas must be substantially more diverse than currently known. This is particularly apparent in the subsets of species inhabiting reefs and soft bottom habitats, whereas accumulation curves of pelagic species and those that occur on multiple habitats tend to decelerate. In both the Eastern Tropical Pacific and Greater Caribbean, species with larger body size and wider geographic and depth distributions were discovered earlier so that newer species tend to be small and restricted in their distribution. A method to predict the total number of species based on the scaling relationship between the observed number of taxa at each taxonomic level and their numerical rank is illustrated for the Red Sea and Greater Caribbean fish faunas. In both cases, this relationship suggests that currently we know 30-40% of the total number of species that occur in each region and that at current rates of species discovery and description a total inventory will take between three and five centuries, depending on the region. Finally, a simulation of the process of species discovery reveals that, given a constant sampling effort over a sufficiently long time, the resulting decelerating species accumulation curve gives the false impression of getting close to a plateau, which in fact substantially underestimates the true regional diversity. This is because the discovery process gradually slows down with each iteration. While a constant proportion of the yet undiscovered species is discovered at each step, a number of species always remains undiscovered and the probability of discovering all of them becomes virtually nil. Nonetheless, new technologies that allow sampling previously unexplored habitats or the development of novel sampling techniques, may significantly reduce the gap in the knowledge of tropical marine fish diversity.

Biography: Fernando is a Professor in the Department of Biology at Universidad del Valle in Cali, Colombia, where he leads the Coral Reef Ecology Research Group. Fernando obtained his B.Sc. degree in Biology-Zoology from Universidad del Valle. Under the support of a Fulbright Scholarship he obtained an M.Sc. degree and later a Ph.D., both in Ecology & Evolutionary Biology, at the University of Arizona in the USA, where he worked on the community ecology and macroecology of reef fishes from the Gulf of California. Fernando uses descriptive and experimental approaches to study the structure and dynamics of fish and coral communities on coral reefs, primarily in the Eastern Pacific. Themes of study include the documentation of local and macroecological patterns of distribution, abundance and diversity; the relationship between fish early life history, genetic population structure and geographic distribution; recruitment patterns; bioerosion by fishes on coral reefs; the long-term dynamics of disturbance and recovery of coral reefs; the determinants of the large-scale spatial variation in species richness; factors that affect the complete documentation of regional fish faunas; and coral reef restoration. Fernando was elected as corresponding member of the Colombian Academy of Exact, Physical and Natural Sciences in 2016, has authored or co-authored 61 journal articles, 24 book chapters and 3 books, and has supervised 15 graduate students and numerous honors students