“Biodiversity Research Requires More Boots on the Ground”
This article was originally published in Nature Ecology & Evolution, October 24, 2017
By Edward O. Wilson
Our incomplete taxonomic knowledge impedes our attempts to protect biodiversity. A renaissance in the classification of species and their interactions is needed to guide conservation prioritization.
The discovery and description of Earth’s biodiversity is the oldest biological science, yet it is the least developed. The number of species characterized and given Latinized names by taxonomists recently passed 2 million. However, the full roster, comprising all those known and others awaiting discovery, is generally believed to be of the order of 10 million; one mathematically reasoned inference put the number of eukaryotic species alone at 8.7 million (1). Thus, a very large fraction of living species, as many as 80%, remains unknown to science. Simply put, we live on a little-known planet.
Take the ants, for example. These relatively well-studied insects are among the most abundant and environmentally dominant animals on the land outside the polar regions (Fig. 1). There are 334 currently recognized genera, of which the second largest in species number is Pheidole. In my study of the New World Pheidole I identified 624 species, including 337 new to science (2). The natural history of fewer than a score of these has been studied in any detail. Meanwhile, new species, discovered mostly in tropical forests and savannas, continue to pour into museum collections.
A second example is the astonishing abundance and diversity of single-celled protists uncovered in studies (3) of the soil and litter of neotropical forests. A large fraction of these mostly new species is parasitic. Their activity seems to be a factor that sustains diversity in insects and other invertebrates, a large majority of which are also unstudied — or entirely unknown.
Biodiversity in the sea is even less well explored than that on the land. The ultramicroscopic bacterium Prochlorococcus, the principal photosynthesizer of the warmer open sea, was first recognized in 1988. These microbes, along with another superabundant marine bacterium, Pelagibacter, are exceeded in turn by viruses, which number on average billions per litre of seawater. A great many, perhaps most, seem to be bacteriophages.
Biologists have scarcely begun to measure the variety of life in Earth’s immense virosphere. Yet even as this domain is more fully explored, we are met by discoveries such as the mysterious ultramicroscopic eukaryotes classified in 2013 as a new phylum, the Picozoa. And beneath the surface of both land and sea is the ‘deep biome’ of rock-eating bacteria and their occasional nematode predators (4) that range downwards to the level at which the risen heat prevents all life — we think.
Most biological research begins and stays with the species as the favoured level of organization, whatever the nature of the trait analysed. The sequencing of highly variable mitochondrial segments — or even of the entire genome — is valuable in its own right, but tells us relatively little about the anatomy, physiology and behaviour of the organisms, and even less about their role in ecosystems. At the highest level, the classification of ecosystems and the rates at which they change tell us a lot. The same is true of ecoregions, relatively undisturbed natural areas consisting of one to multiple ecosystems (5). But the delineation of species and the rates of their individual population growth or decline tell us much more, and with far greater exactitude.
Many of the less-explored groups are immediately available for fruitful research on biodiversity — for example, the mites, soil-dwelling spiders, schizomid arachnids, parasitoid wasps, springtails, tardigrades, nematodes, rotifers, parasitic flatworms, midges, crustaceans, microscopic algae and a seemingly infinitude of microscopic fungi. I have often offered the following suggestion to new graduate students: if you go outside and pick up the first small organism you see, you will hold in your hand a PhD project.
As a rule, the only scientists able to discover and analyse the fine detail of biodiversity needed at the species level are specialists: the entomologists, herpetologists, nematologists, mycologists and others who devote their careers to the biology of their chosen group. They alone develop the fingertip familiarity with the species and a feel for the intricacy of organisms in the environment. They accumulate not merely data and syntheses but also impressions and intuitions beyond the reach even of Big Data technology. This deep peripheral knowledge leads to new questions and lines of research beyond ordinary imagination.
Unfortunately, research into the biology of diversity has been largely abandoned by universities in favour of focus at the molecular and cellular levels of a small number of ‘model’ species. Museums around the world with outstanding collections have been unable to increase their curatorial staff to compensate for this shortfall.
The Linnaean enterprise has taken a new urgency with the recognition that global extinction rates have risen to between 100 and 1,000 times the rate during pre-human history (6) (approximately 900 times in North American freshwater fishes, for example (7)). It makes sense, when surveying and mapping species for conservation practice, to focus first on those groups of which we have the greatest knowledge and can move most quickly to completion. Among them are the flowering plants, vertebrates, corals, butterflies, dragonflies and damsel flies, araneid spiders and mosquitoes. From this distribution information alone, which we could assemble in a decade, it should be possible to map the optimum placement of biodiversity-defined reserves. Some of these distribution studies already exist and conservation planning on the basis of them is ongoing (8).
Advances in molecular genetics and information technology are assisting crucial biodiversity studies (9). The reading of highly variable segments of mitochondria allows reliable identification of specimens to species level, and even to different life forms or isolated tissue fragments of the same species. Complete genomes make possible quick scans of entire faunas and floras. They also permit the reconstruction of the evolutionary history by which related species have multiplied. Yet in the broader perspective of biodiversity, these studies are the equivalent of aerial surveillance; what is more needed are boots on the ground.
The ongoing neglect of biodiversity research impedes the progress of conservation of life at all levels in all taxonomic groups. It also diminishes the capacity to meet one of the greatest challenges to the biological sciences, rising just over the horizon: the origin, evolution and equilibration of ecosystems. The problems presented by ecosystem analyses are equivalent in complexity to those presented by the human brain. They can be solved by nothing less than a Linnaean renaissance, in which each one of the millions of Earth’s species still surviving is discovered and its role in the biosphere increasingly well documented.
1. Mora, C., Tittensor, D. P., Adl, S., Simpson, A. G. B. & Worm, B. PLOS Biol. 9, e1001127 (2011).
2. Wilson, E. O. Pheidole in the New World: A Dominant, Hyperdiverse Ant Genus (Harvard Univ. Press, Cambridge, 2003).
3. Mahé, F. et al. Nat. Ecol. Evol. 1, 0091 (2017).
4. Tranter, M. Nature 512, 256–257 (2014).
5. Dinerstein, E. et al. BioScience 67, 534–545 (2017).
6. Lamkin, M. & Miller, A. J. BioScience 66, 785–789 (2016).
7. Burkhead, N. M. BioScience 62, 793–808 (2012).
8. Wilson, E. O. Half-Earth: Our Planet’s Fight for Life (Liveright, New York, 2016).
9. Pennisi, E. Science 355, 894–895 (2017).
Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138-2902, USA
Edward O. Wilson
The author declares no competing financial interests.
Correspondence to Edward O. Wilson.