2017) and a few molecules, instead of whole phenotypes on uncultured microbes (Konstantinidis et al. 2017).
The issue now is to understand that it is essential to discover the unknown 80% of biodiversity for several well-defined scientific reasons, more than for the thirst for new knowledge or for a compulsive collection of new species.
First of all, the laws of life have rather varied degrees of generality; from heredity to the functioning of ecosystems, for example, there are several orders of magnitude of difference in this respect! Many laws or principles require the study of more particulars in order to reach generality, given the variation that is the intrinsic property of living things (Montévil et al. 2016). Clearly, we need to know about more organisms and the particular cases of their biology in order to be able to claim to generalize. The rules of representativeness, dominance or abundance, stated as truisms, are often misleading in living organisms. For example, it has recently been documented that rare and scarce species often fulfill disproportionately important functional roles within ecosystems (Mouillot et al. 2013).
In contrast to universals, particulars very frequently remind us of how many pathogenic, invasive species are discovered in this way, having already crossed half the planet, causing us great concern. This is as much the case for HIV (Barré-Sinoussi et al. 1983), an obscure retrovirus from an African primate, as for an invasive and unknown flatworm imported from South America, threatening the fauna of our soils and their faunal balance (Justine et al. 2020). Not a week goes by without a species new to science presenting a question to our societies. The COVID-19 pandemic is a dramatic demonstration of this: here again, a few poorly known bats and pangolins harbor unknown (and described for the occasion) coronaviruses whose genetic recombination is putting the human world at a standstill (Hassanin et al. 2020). This is also the case for viruses and viroids of plants that are still largely unknown, and vectors of devastation in some plantations (Maurel 2018).
The issue of bio-inspiration (Benuys 1997) is another opportunity to understand how much the diversity of living things contains wonders from which we can draw inspiration for more sustainable societies; so many particulars (structures, functions, etc.) in different species whose natural function can be transposed to functions of human interest. Practicing bio-inspiration beyond random discoveries of opportunity requires a broad and reasoned exploration of living things and the relationships between their structures and functions.
Particulars are also often geographical rather than purely taxonomic. Each state, government or municipality needs to be aware of local biodiversity in order to develop a reserve or environmental, agricultural or health policies (Pellens and Grandcolas 2016). These are all reasons to be aware of local fauna and flora with their innumerable numbers of endemic species (Caesar et al. 2017). It is worth remembering the order of magnitude of these numbers and that there are, for example, 40,000 species of insects in metropolitan France alone (Gargominy et al. 2014).
Even if we focus on a few species for reasons of immediate interest, it is essential to know their close relatives. Knowing the meaning, adaptive character and selection regime of the traits of organisms, whether they are genotypic or phenotypic models, requires an understanding of their history (Jenner 2006). Is it necessary, once again, to quote Dobzhansky (1973) – “nothing in biology makes sense except in the light of evolution” – to be convinced of this. Reconstructing the origin and evolution of the traits of an organism of interest requires knowing not only its close relatives, but also a very large part of the living world. How many fundamental traits has the human species inherited, the understanding of which is based on their structure and function at the Metazoan scale (more than a million species!)? This presupposes an adequate taxonomic sampling of life, which is not necessarily limited to known species, but which must be searched for out in the field in order to find unknown species whose lifestyles have sometimes been long surmised.
The entirety of this book is therefore dedicated to these approaches to exploring the diversity of life, each of them showing the crucial need we have for exploratory approaches. “Exploratory”, which is easy to understand when reading this volume, does not refer to a kilometric description of specific characteristics, but to an organization of knowledge and hypothesis tests, based on a large sampling of living species – a large part of which is, strangely, still unknown to us, even though we come into contact with it every day. Without further delay, we must not suffer from or destroy biodiversity, but study it in order to integrate it sustainably into our societies.
References
Barré-Sinoussi, F., Chermann, J.C., Rey, F., Nugeyre, M.T., Chamaret, S., Gruest, J., Dauguet, C., Axler-Blin, C., Vezinet-Brun, F., Rouzioux, C., Rozenbaum, W., and Montagnier, L. (1983). Isolation of a T-lymphotropic retrovirus from a patient atrisk for acquired immune deficiency syndrome (AIDS). Science, 220, 868–871.
Benyus, J.M. (1997). Biomimicry: Innovation Inspired by Nature. Harper Perennial, New York.
Bouchet, P. (2006). The magnitude of marine biodiversity. In The Exploration of Marine Biodiversity: Scientific and Technological Challenges, Duarte, C.M. (ed.). Fundacion BBVA, Bilbao, Spain, 31–62.
Caesar, M., Grandcolas, P., and Pellens, R. (2017). Outstanding micro-endemism in New Caledonia: More than one out of ten animal species have a very restricted distribution range. PLOS One, 12(7), e0181437.
Dobzhansky, T. (1973). Nothing in biology makes sense except in the light of evolution. The American Biology Teacher, 35, 125–129.
Gargominy, O., Tercerie, S., Régnier, C., Ramage, T., Schoelinck, C., Dupont, P., and Poncet, L. (2014). TAXREF v8.0, référentiel taxonomique pour la France : méthodologie, mise en œuvre et diffusion. SPN report, 42.
Grandcolas, P. (2017). Loosing the connection between the observation and the specimen: A by-product of the digital era or a trend inherited from general biology? Bionomina, 12, 57–62.
Grandcolas, P. (2018). The view of systematics on biodiversity. In Biodiversity and Evolution, Grandcolas, P. and Maurel, M.-C. (eds). ISTE Ltd, London and John Wiley & Sons, New York, 29–38.
Hassanin A., Grandcolas P. & Veron G. (2020). Covid-19: Natural or anthropic origin? Mammalia, 000010151520200044.
Hawksworth D.L. and Lücking R. (2017). Fungal Diversity Revisited: 2.2 to 3.8 Million Species. In The Fungal Kingdom, Heitman J, Howlett BJ, Crous PW, Stukenbrock EH, James TY and Gow NAR (eds). American Society for Microbiology, Washington, DC, 79–95.
Jenner, R.A. (2006). Unburdening evo-devo: Ancestral attractions, model organisms, and basal baloney. Development Genes and Evolution, 216, 385–394.
Justine, J.L., Winsor, L., Gey, D., Gros, P., and Thévenot, J. (2020). Obama chez moi! The invasion of metropolitan France by the land planarian Obama nungara (Platyhelminthes, Geoplanidae). PeerJ, 8, e8385.
Konstantinidis, K.T., Rosselló-Móra, R., and Amann, R. (2017). Uncultivated microbes in need of their own taxonomy. The ISME Journal, 11, 2399–2406.
Le Guyader, H. (2018). Classification et évolution. Le Pommier, Paris.
Linnaeus, C. (1758). Systema Naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, 10th edition, volume 1. Laurentii Salvii, Holmiae, Stockholm.
Mahner, M. and Bunge, M. (1997). Foundations of Biophilosophy. Springer, Berlin.
Maurel, M.-C. (2018). À la frontière du vivant: les viroïdes [Online]. The Conversation. Available: https://theconversation.com/a-la-frontiere-du-vivant-les-viro-des-90500.
May, R.M. (1988). How many species are there on earth? Science, 241(4872), 1441–1449.
Mayr, E. (1982). The Growth of Biological Thought: Diversity, Evolution, and Inheritance. Harvard University Press, Cambridge.
Montévil,