The extinction of certain species will completely disrupt the role of others within ecosystems (illustration).
Slavek Ruta / Shutterstock / SIPA
Over 30,000 species are threatened with extinction within a century.
According to a study, in which Toulouse scientists participated, the disappearance of some of them will affect the functions of other species.
Because if they sometimes have points in common, certain endangered species have unique or rare functions that play a role in the balance of ecosystems.
You miss a being and everything is depopulated.
Or rather, everything is turned upside down.
This is very likely to happen when today's endangered species become extinct over the next few years.
For researchers, these extinctions will lead to a global reorganization of the role of species in the functioning of ecosystems, according to a study published in
A group of scientists from Paul-Sabatier University and Estonia have worked on the functional characteristics of 70,000 species, whether it is their size, their age of first reproduction, their longevity or their diet.
Sometimes reptiles, amphibians, birds, mammals or even freshwater fish share common points.
But sometimes some functions are unique or shared by few species.
“For example, we have very few very large mammals that weigh more than a tonne and yet we will go from one to fifty tonnes in whales.
We have a huge range of functions which is covered by only a very few species, ”explains Sébastien Brosse, one of the co-authors of the study, member of the Laboratory of Evolution and Biological Diversity in Toulouse.
Using mathematical models, they tried to see what it would look like if certain endangered gorillas or fish were to disappear.
“Overall, if the extinctions are consistent with predictions, the job losses in 100 years would be relatively small.
They would be between 0.3% for reptiles and 5.1% for fish.
But this is a trompe-l'oeil result, we see a slight loss but we considerably increase the share of functional space occupied by a single species ”, continues the researcher.
And a decline in the diversity of roles played by each.
Roles in the great ecosystem scenario
However, if we take the great apes, they play a role in the dissemination of seeds, and we know that tropical forests are seeded by their droppings.
If we look at the elephants, they also do important seed transport.
The hippos transfer matter, they will graze in the savannah and go to make their coats in the water and thus maintain the African aquatic environment.
As for birds, large birds of prey and scavengers, such as the Andean Condor, play a role in cleaning up ecosystems by consuming the carcasses of dead animals.
“If we look at the species of fish, there are detritivores or predators, which will somewhat control the food chain, the fact of losing these species can disrupt the functioning of ecosystems,” says Sébastien Brosse.
And the clear waters could turn cloudy, which would be a source of concern for humans as well.
Not to mention another direct impact.
“We often eat large species, such as fish.
If they disappear, it can lead to malnutrition problems ”, concludes the scientist.
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