Pick and Choose

Pick and Choose

Deciding which species to keep and which to discard? Maybe there’s a simple answer

This story can also be read on Medium

About  ten thousand years ago, a hunter-gatherer nomad tamed some wild plants.  It’s unlikely he knew it, but this was the first step of a long  technological progression. It allowed our ancestors to settle down and  build the foundations for today’s civilization.

And we have never looked back.

Today, croplands and pastures cover about 40 % of the globe’s lands⁠. In those lands, we exploit domesticated plants  and animals to gain food, fibres, and fuel. These goods are usually sold  by the owner of the land, bringing him some sort of an income.

This  give and take forms the basis for much of our society today. And  because everything these days seems to centre around money, these  biodiversity benefits are measured and valued as well.


Academics such as environmental economists and conservation ecologists have a term for this. They call it “provisioning ecosystem services”.  Ecosystem services are defined as “services provided by nature”, which  include supplying (“provisioning”) services, regulating services, and  cultural services.

The  products of agriculture have a clear and obvious value — a value we can  see everyday on our shopping and grocery bills. However, other  ecosystem services might not be as clearly of value — such as the  regulation of carbon and nitrogen cycles, maintenance of soil fertility,  and natural pest control, to name a few.

To be clear, these not-so-obvious services do have a very, very high value. An estimate done in 1997⁠ put their worth at somewhere between 16 and 54 trillion American dollars.

The ecosystems provide them for free.

But  we’re thinking economically. For the sake of efficiency in  conservation, and in trying to optimise agriculture, it’s interesting to  know what exactly provides those services, and how we can help the  process along.


The  first thing to be established is that all these services exist only  because of the species in the ecosystem. Intuitively, this make sense,  because the ecosystem is the species.

The second is that some species seem to be pretty much useless.

In a study published in 2010 about wild pollinators, Pr. Kleijn⁠  showed that almost 80% of the pollination services were done by only 2%  of the pollinator species. Moreover, the dominant species were usually  abundant and widespread in the landscape. It showed that we could more  or less lose most species of pollinators without any large impact on  pollination and production of fruits.

Beyond  being useless, some species are actually antagonists to ecosystem  services. They only serve to make management of the ecosystem more  complicated. These species are usually animal pests, plant pathogens,  and weeds.

Uncontrolled  pests will reduce the quantity and the quality of the crop yield,   which further impacts the income of the farmer. People think that up to one third of all cultivated crops are destroyed or damaged by pests.

The  other kind of antagonists are actually outright enemies of the system.  For example, cuckoo bumblebees lay their eggs in bumblebees’ brood  cells. By doing this, they increase the chances of their own children  surviving, but they also decrease the growth and reproduction of a key  pollinator species.

Losing these kinds of species won’t have any impact on ecosystem services and can even enhance them.

Other species, however, are not so disposable.


The  most important species are possibly the ones directly raised and  introduced by humankind into the ecosystem. Think of the plants we get  food from, for instance.

Obviously,  these species need to be conserved because they produce goods with a  direct market value. The Food and Agriculture Organization estimated a  total production value of 2.55 trillion US dollars for all agriculture  production in 2014, including animal and vegetable production.

Along this vein, all the species which help with the growing of edible species should be preserved. The bees  pollinating the crops, the nitrogen fixing microorganisms enhancing soil  fertility, the pest controllers.

For  example, natural pest enemies are actively bred and released in  greenhouses in place of chemical pesticides⁠. Unlike chemicals, they  have the advantage of the ability to evolve with the pest, so they’ll  always be able to do their job.

But sometimes, it’s difficult to know exactly which species provide a given service.


Today, we do not know all the species of flora and fauna that exist on Earth, particularly insects and soil dwellers [Scheffers et al. 2012]⁠. Moreover, even where we do know of a species, we do not know the specific characteristics of every species.

And,  as you might be able to guess, it is something of a mammoth task to  identify the properties of each species in a given ecosystem.

Funding  is often limited. So is workforce. This makes it almost impossible to  identify and study each species from the field to understand it’s role,  and even harder to judge the value of conserving it.

Most  experiments also have their limitations. They are often done in a  closed system that cuts off the interactions between species, or don’t  consider any movement such as migration and dispersal. We also can’t  interfere with the species’ behaviour in natural conditions, so we have  to limit predictions to the value of the ecosystem service it might provide.


So  far, we’ve been focusing on the “provisioning” and “regulating”  services; there are, however, other kinds of services that nature  provides, and they’re far less clinical in nature.

Biking  in the countryside and observing butterflies around colourful fields is  entertaining. A naturalist might make a collection of those butterflies  and try to identify all the local species.

This activity and the joy it brings could not possibly exist without a diversity of butterflies and other related species.

Each  species which disappears is a part of human culture and heritage flying  away. The common names people use to identify species may disappear.  The souvenirs, the descriptions, and the stories about species will fade  away.

Agricultural landscape managers need to conserve biodiversity in order to conserve all the culture it gives us.


Biodiversity  may be useful to us in the future as well. Considering the loss of  genetic diversity within and between cultivated species, the capacity to  feed the people may someday be threatened.

Historically, genetic erosion within crop has only brought brought famine and misery, like in 1970,  when a fungus destroyed more than half of the maize crop in the southern  US.

Today, most of our diet depends on only 12 plant species,  and any harm to them could greatly hurt the world’s food situation. To  ensure nutrition and food security, it is important to introduce a  higher diversity of crops in our agriculture.

Of  course, species, varieties and in general genetic diversity can be  conserved ex-situ in seed banks. But in these cases, the plants don’t  have the chance to continue their evolution race against diseases and  fast-changing conditions. It’s like leaving one country’s military in  suspended animation while the other continues to develop. So it’s  probably better to keep those species and varieties in our agricultural  landscape.

In  the future, a crop genetician may need those species to create  genetically modified organisms that are able to cope the consequences of  climate change.


From  a purely utilitarian point of view, there’s no reason to conserve  biodiversity to preserve the ecosystem. Finding those species that are  highly active and efficient should be a priority.

But  today, we lack the knowledge to identify all the “useful” species, and  we must check the influence of the different interactions between all  the species, useful and useless.

And now here’s a shortcut: instead of choosing which species to keep, why not keep them all?

We  can avoid expensive, time-consuming research by simply conserving  biodiversity as a whole. Because, really, who knows what will come in  the future? We’re witnessing a high-speed global change which may  someday threaten humanity — and if that happens, biodiversity could be  our best insurance.

As a bonus, we keep the colourful butterflies and the awesomeness of the German word «schmetterling».


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