EDITORIAL : Taxonomy in the century of extinctions : taxonomic gap, taxonomic impediment, taxonomic urgency

Taxonomy in the century of extinctions: taxonomic gap, taxonomic impediment, taxonomic urgency Our knowledge of the living species of the earth is still dramatically incomplete.Actually, few domains of scientific knowledge are in such an unsatisfying situation.Taxonomists have so far described less than 2 million species, whereas, using various methods, the total number of species was estimated to at least 7-8 million, but perhaps 10, 50, 100 million or even more (Groombridge, 1992;Heywood & Watson, 1995; Reaka-Kudla et al., 1997).This huge taxonomic gap (Dubois, 2010a) is both quantitative and qualitative, as very little is known of most of the species that have been "described" and named so far (Dubois, 1998).If the work of increment of our database on specific diversity continued at the same pace as in the past, centuries would be necessary to complete our inventory of the planet's species (González-Oreja, 2008).However, time is pressing, because of the biodiversity crisis (Wilson, 1985).The aggressions of the biosphere by our civilisation result in a drastic destruction and disappearance of natural ecosystems and, combined with other threats (physico-chemical and biotic pollution, over-exploitation by man, etc.), entail mass extinctions of species which will be irreversible.Many of the species that are currently disappearing with the forests, aquatic and other habitats that harboured them, will carry away forever with them not only molecules or other inventions of life that could have been useful to medicine, agronomy or other human needs, but also a plethora of irreplaceable information on biodiversity, evolution, adaptation and innovations, not to mention their aesthetic and cultural value.No serious hope exists to really stop or even significantly reduce the destructions on hand, as they are due both to human demographic growth and to the destructive kind of relations our current societies have with their environment, two factors that are not likely to change in the coming decades.The taxonomic urgency (Dubois, 2010a), i.e., the imperious need of an acceleration of our taxonomic inventory of the planet (Wheeler et al., 2004), is currently far from having been identified by our governments, by the decision-makers in matters of scientific research and by most scientific institutions.Before it is too late, much more funding should be invested into taxonomic research, museum collections, training and hiring of professional taxonomists.The vanishing species of our planet are not in the computers and sequencers of our cities, but in the threatened natural habitats, and the main limiting factor for the increase of our knowledge on animal and plant species is field work devoted to their discovery, study and collection in the wild (May, 2004).It is of utmost importance to consider the discovery, collection, storing in collections, study and description of specimens and tissues of the still unknown species of the biosphere, before they turn extinct, as an absolute priority for biology in our century of extinctions (Dubois, 2003).This is in fact much more urgent than clarifying their phylogenetic relationships or studying the modalities of their evolution, because evolution is not teleological: once they are extinct, all possible information about them will be lost and forever unavailable and no evolutionary theory or model, no "predictive taxonomy", will ever tell us what these vanished species looked like and what were their characters.Molecular data on cladistic relationships are certainly very useful and interesting to generate hypotheses on the relationships between the known taxa and on the evolutionary pathways that gave birth to them.However, and however complete and accurate they can be, they will never allow to predict the existence and the characters of taxa that have not yet been collected and studied.The group of amphibians, that has long remained under-studied by zoologists, has prompted renewed and deeper interest in the last decades.Several new "extraordinary" discoveries were made in this group, which provide a new vision of the diversity, evolution, adaptations and "inventions" of these animals.Strikingly, most of these unexpected discoveries owe nothing to phylogenetic studies per se, although in some cases subsequent phylogenetic research has brought interesting additional data.