By Juan Gayá Vilar
Approximately two species of vertebrates become extinct each year, thus gradually reducing the fauna of the world. Now, research published in the journal PNAS analyzes the consequences of the global decline of these animals on natural environments and the living beings that share habitat with them.
Of the 177 mammals studied,
all have lost 30% of their habitat
To carry out the work, Gerardo Ceballos, professor at the National Autonomous University of Mexico, together with colleagues from Stanford University, have mapped the geographic distribution of 27,600 species of birds, amphibians, mammals and reptiles - half of the terrestrial vertebrate species known. They have also analyzed the decline in populations of 177 extensively studied mammals between 1990 and 2015.
Ceballos participated in a study, published inScience in 2014, which warned of the sixth mass extinction.
The results obtained in the current work show that 30% of vertebrate species are reducing the number of populations and the variety of species. In addition, of the 177 mammals studied, all have lost 30% of the territory they inhabit and more than 40% have seen their habitat reduced by 80%.
The study maps indicate that up to 50% of the number of animals that lived on Earth have disappeared.
Experts point to the tropical and temperate regions as the places where there are a greater number of extinct species, and they assure that the large mammals of Southeast Asia are the group of animals that has lost the highest percentage of habitable territory.
It is necessary to increase the protection areas
and preserve plant and animal populations
in regions dominated by man
"The massive decrease in families and animal species is mainly due to: the loss and fragmentation of their habitat, hunting, trade, overexploitation of the territory and the appearance of invasive species," Gerardo Ceballo told Sinc.
The reduction in the number of animals and biological diversity, apart from assuming the 'prelude' - as the authors of the work call it - of a species extinction, also implies the loss of crucial services offered by ecosystems, such as the pollination of bees, natural pesticide control or water purification.
In addition, this circumstance alters the ecological networks in which all living beings benefit, causing a cascade effect.
The Paris Agreement is positive but insufficient
to stop the extinction of species
To reverse this situation, Ceballos advocates reducing the growth of the human population, reducing consumption and betting on the use of green technologies. It also considers it necessary to increase the areas of protection and preserve the populations of animals and plants in regions dominated by man.
In relation to the Paris Agreement, the researcher values this treaty as positive but insufficient when it comes to curbing the current situation of animals.
"The Paris Agreement will help reduce the disappearance of animal populations, but it is not enough" and adds "we need international measures aimed at mitigating trade in threatened species and reducing poverty in developing countries to protect the natural habitats and biodiversity ”.
"We have a short window of time to act, although it is closing rapidly," concludes the author.
Gerardo Ceballos placeholder imageet al. "Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines".Proceedings of the National Academy of Sciences –PNAS–(July 10, 2017)
Photo: A female gorilla with her four-month-old calf in the Democratic Republic of the Congo. / Conservation International | Russell A. Mittermeier