Mammals: pathways to survival and extinction
The impact of human activities on the environment, which has considerably increased since the 70s of the last century through the third industrial revolution, is substantially changing the ecological processes underlying life on earth.
One of the main effects of the intensification of anthropic activities is the gradual disappearance of various native species, with tragic consequences on the ecosystem services linked to it.
In a new study published on the journal Nature Communications, the team of researchers coordinated by Michela Pacifici of the Department of Biology and Biotechnology "Charles Darwin", compared the distribution of a representative sample of terrestrial mammals in the 1970s and today, observing approximately 75% of these species has gone through changes.
The researchers have also identified the causes underlying contractions and expansions of species range, i.e. the area inhabited by each species, including both anthropic and biological factors such as body mass and reproductive strategies.
"We discovered – says Michela Pacifici – that one out of five species has lost more than 50% of its past range. Main causes may be global warming, loss of natural areas and the increase of human density. All these factors especially affect large species such as the white rhinoceros, the Asian elephant and the addax."
Understanding what variables are involved in their decline is fundamental in order to plan the necessary conservation actions, especially considering the several threats the mammals are subject to, including climate changes.
"Previous studies – notes Carlo Rondinini, coauthor of the paper and coordinator of the Global Mammal Assessment program, a partnership between Sapienza and the International Union for Conservation of Nature (IUCN) – show that large mammals are the only species able to move fast enough to track climate change. But from the present study, it is clear that large mammals are those suffering the direct actions of humans more than any other species. Hence, implementing all the necessary measures to favour their natural movements to suitable areas remains a fundamental step to prevent large mammals from disappearing."
The research highlights that few species have expanded their range, and that these species have fast reproduction rates, a generalist diet and lower body mass.
"This study – adds Moreno Di Marco, senior author of the study – proves, once again, that there are many mammal species rapidly declining as a result of anthropic pressure whereas only a few species can adapt and potentially take advantage of global change, thanks to their biological characteristics."
"Our data – concludes Pacifici – demonstrate how a high percentage of mammals, including numerous charismatic species, have in fact disappeared from areas where they used to live until 50 years ago. This alarming result shows how important it is to understand the risk factors which led to the local extinction of a species so as to operate proactively and decrease the risk of additional loss."
Global correlates of range contractions and expansions in terrestrial mammals - Michela Pacifici, Carlo Rondinini, Jonathan R. Rhodes, Andrew A. Burbidge, Andrea Cristiano, James E. M. Watson, John C. Z. Woinarski & Moreno Di Marco - Nature Communications volume 11, Article number: 2840 (2020) https://doi.org/10.1038/s41467-020-16684-w
Department of Biology and Biotechnology "Charles Darwin"