In the 20th century, at least 543 species of vertebrates became extinct and, if this continues, in the next twenty years many more could disappear. It is the conclusion of an article published in PNAS by the same authors who in 2015 already warned, in a work echoed by the journal Science Advances , that the sixth mass extinction is already underway.
The new article indicates that the wildlife trade and other human impacts have wiped out hundreds of species and brought many more to the brink of extinction at an unprecedented rate. The consequences of this destruction also affect our own survival as a species, and this message should no longer sound like apocalyptic scaremongering as we are currently experiencing it with the COVID-19 pandemic. Experts warn that, if the destruction of nature is not stopped, we will suffer more pandemics.
“When humanity exterminates other creatures, it is cutting its own seat, destroying fundamental parts of our life support,” explained Paul Ehrlich, professor emeritus at Stanford University. ” The conservation of endangered species should be raised to the level of national and global emergency, as well as the climatic alteration to which it is linked .”
Study in vertebrates
The researchers analyzed the abundance and distribution of various critically endangered species, and found that 515 species of terrestrial vertebrates are on the brink of extinction, meaning fewer than a thousand individuals remain, and about half survive with populations less than the 250 individuals. Most of the endangered species are concentrated in tropical and subtropical regions that are affected by human invasion: another recent study has revealed that every six seconds an area of tropical forest equivalent to a football field is lost.
The loss of these species could have a ripple effect on others, creating the conditions for a chain reaction in which the disappearance of one species destabilizes the ecosystem, putting others at greater risk of extinction. The authors give an example: around the year 1700, sea otters were hunted, the main predator of sea urchins, which in turn feed on algae. The decline in the otter population led to the massive kills of algae, and the sea cow that also fed on them eventually became extinct.
“What we do to face the current extinction crisis in the next two decades will define the fate of millions of species,” explained the study’s lead author, Gerardo Ceballos, principal investigator at the Institute of Ecology at the National Autonomous University of Mexico. ” We are faced with our last chance to make sure that the many services that nature provides us are not hopelessly sabotaged .”
Millions of years of vertebrate evolutionary history at risk
Another study that has just been published in the journal Nature Communications offers a map of the evolutionary history of all the terrestrial vertebrates of the world, and explores how areas with large concentrations of evolutionarily different species are affected by this “human footprint” each time. higher. The work also indicates the endangered species that should be prioritized for their conservation, in order not to destroy what evolution has achieved over millions of years.
“Being ‘evolutionarily distinct’ means you don’t have close living relatives,” explains Shai Meiri, a researcher at Tel Aviv University. “In other words, you are alone on your branch of the evolutionary tree of life. Anteaters, crocodiles and kiwis were separated from their closest evolutionary relatives tens of millions of years ago and have a unique evolutionary history .”
“This new study highlights which species should be prioritized for conservation, based on their evolutionary uniqueness and the intense human impact on the environments where they are believed to inhabit,” Meiri explains. According to the research, the greatest losses in evolutionary history will be driven by the extinction of entire groups of closely related species, such as pangolins and tapirs, and by the loss of highly evolutionarily distinct species, such as the ancient Chinese crocodile lizard ( Shinisaurus crocodilurus ); the shoebill ( Balaeniceps rex ), and the aye-aye ( Daubentonia madagascariensis ).
The study also identifies regions where concentrations of irreplaceable diversity are currently under little or no human pressure, particularly in the Amazon rainforest, the highlands of Borneo, and parts of southern Africa.
Referencias: Ceballos et al. 2020. Vertebrates on the brink as indicators of biological annihilation and the sixth mass extinction. PNAS https://doi.org/10.1073/pnas.1922686117
Gumbs et al. 2020 Global priorities for conservation of reptilian phylogenetic diversity in the face of human impacts Nature Communications volume 11, Article number: 2616 (2020)
