BIODIV'AMU

" Only one species is responsible for the Covid-19 pandemic: ours", (J. Settele, S. Díaz, E. Brondizio and P. Daszak, IPBES press release, 27 April 2020).

What is biodiversity?

In our communication society, certain words become emblems of causes to be defended or fought for. The process of symbolic appropriation of these words by the general public leads to abuses. The concept of biodiversity is a perfect example of this risk of semantic "blurring" when the media take it over.

For a non-specialist, biodiversity is often the possibility of observing many animal and plant species around him. This implicit definition has a "decorative" connotation, and the desire to preserve this diversity of life can be easily contested by those who believe that the disappearance of a few species will only bother "conservative" naturalists concerned with preserving the integrity of the "catalogue" of life, just as one carefully preserves a museum collection. There is this idea that progress inevitably involves a bit of "breakage" in the living world, whether non-human or even human (cf. the numerous health scandals linked to pesticides in the countries of the South).

Climate change, the other major ecological cause that receives more media attention and gives rise to a global awareness, has the advantage of being translated into figures that can be understood by everyone. Predicting a few degrees more on average speaks to everyone because it refers to a shared sensitive experience. Moreover, it is easier to get a state or a large company to make a "gesture" for the climate by acting to reduce the consumption of fossil fuels than to act for biodiversity, which is impacted in a much more varied and insidious way by deleterious actions at different levels. Deforestation, the expansion of intensive agriculture, mining and infrastructure development, as well as the exploitation of wild species, are all attacks on biodiversity that respond to economic, social and even cultural needs. Combating climate change will therefore not be enough to resolve the issue of environmental damage.

Translating the erosion of biodiversity into figures makes one dizzy: 10% of insect species and 25% of all species are threatened with extinction in the medium and short term. The rate of species extinction is 100 to 1000 times higher than the natural rate of extinction. In France, 19% of species are threatened or extinct.
To understand why biodiversity must be preserved, we must first define it clearly: the diversity of all living organisms as well as all the relationships and interactions that exist, on the one hand, between the living organisms themselves, and, on the other hand, between these organisms and their living environments. Biodiversity is therefore inseparable from ecosystems that have evolved over hundreds of thousands of years. We can distinguish three levels of biodiversity: those of individuals (genetic diversity), species (specific diversity) or living environments (ecosystem diversity). Genetic diversity makes it possible to adapt to environmental changes and thus ensure the survival of living organisms.

Why preserve biodiversity?

Many species have an immediate and quantifiable impact on the environment; let's take the example of pollinating insects, whose disappearance would irreparably destabilize ecosystems. Other species seem to have a more limited impact on their ecosystems; but it is almost impossible to anticipate the cascading effects produced by the disappearance of one species or the uncontrolled proliferation of another. The particularity of the human species is its deleterious impact in the very short term on certain species, which does not allow the ecosystem to quickly recover a virtuous balance.

Two examples of the consequences of negative human impacts on biodiversity:

• Concerning deforestation, it is inductive to think that retreating the forest in tropical areas is also eradicating malaria. On the contrary, research has shown that a 10% increase in deforestation, i.e. about 1600 square kilometres of additional logging, resulted in a 3.3% increase in the rate of malaria transmission (MacDonald, 2008).
• Pesticide use in agriculture has long had a serious impact on species. The effects of organochlorine pesticides, particularly di-chloro-diphenyl-trichloro-ethane (DDT), are well known on Peregrine Falcons. DDT has several deleterious effects: damage to the nervous system leading to maladaptive behaviour unfavourable to the species, sterility or direct mortality, disruption of calcium transfers from eggshells leading to a decrease in density or even thinning of the shell (more frequent breakage) and, to a lesser degree, a teratogenic effect on embryos and young (Ratcliffe, 1993). The example of the peregrine falcon is a perfect illustration of how a physical substance with no immediate effect on the climate can seriously alter the survival of a species, like neonicotinoids for bees.

The current pandemic, a major consequence of the erosion of biodiversity.

With reference to the introductory sentence, we can consider that different processes have created the "perfect conditions" for the spread of diseases from wildlife to humans:
- The destruction of environments - thus ecosystems - resulting in the release of living organisms - including pathogens - previously neutralized by stable biological relationships for millennia.
- Deforestation and soil artificialisation, by depriving them of food, lead many wild species to move closer to urban areas.
- The connection between (i) the intensive breeding of domesticated species that are genetically impoverished and vulnerable to numerous pathologies: through ignorance of genetics, we involuntarily select the capacity of certain species to carry potentially mutable pathogens, and, (ii) the exploitation of wild species captured and/or bred for human consumption or fur often crowded in conditions where stress, through the depression of the immune system, favours the circulation of "novel" pathogens in urbanised areas.
- The transfer between species and the mutation of pathogens that reach humans with potential variants/mutants in the making.
- The explosive growth of long-distance travel in recent decades indirectly increases the risk of unpredictable mutations by transferring pathogens to ecosystems radically different from those of origin, thus increasing the randomness of their mutations.
"An estimated 1.7 million unidentified viruses of the type known to infect humans are present in mammals and aquatic birds. Any one of them could be the next 'disease X' - potentially even more disruptive and deadly than Covid-19" (Settele, 2020)

Biodiversity: knowing it to preserve it

Once the nature of biodiversity and the need to preserve it have been emphasized, it is not easy for non-specialists to grasp. This point is important because in order to be motivated to take living beings into account, one must be able to identify them in order to describe them and see them evolve. The first steps of the apprentice naturalist are always gratifying because the discoveries and connections between species are countless. But the inventory activity quickly becomes a matter for specialists and it may be interesting, particularly through participatory science programmes, to make it accessible to as many people as possible. On the other hand, it is judicious to deploy an activity on a shared place, that of the campuses of Aix-Marseille University. These places devoted to our professional activities are very diverse. To take Marseilles alone, between the Saint Charles campus and the Luminy campus, the environment is radically different. However, even the most urbanized campus can harbor significant biological riches.

The Biodiv'AMU mission, based on existing initiatives, aims to raise awareness of local biodiversity among staff and students. The actions will be based on the development and semi-sanctuary of certain natural areas, on the practice of participatory science around inventories of flora and fauna, campus events, an evolving web page with information and attractive headings (e.g. species of the month) and the list goes on. This mission also intends to influence AMU's development strategy by promoting projects that take into account the maintenance and development of biodiversity.