Researchers have assembled a family tree and atlas of nearly 6,000 mammals extant and extinct, and its the most comprehensive one of its kind to date. The supporting article has been published in the journal Ecology.
Range-displaying maps are used to explore trends in biodiversity and measure the effect of climate change on various plant and animal species, but these tend to focus on where these organisms exist today. That is, they do not consider a species' historical range. Many mammals, like, say, the brown bear, which is found almost exclusively in Russia and Alaska in 2018, have had their ranges cut and changed because of human activity, whether that be hunting, habitat destruction, or both. As the map below shows, the brown bear used to extend all the way down to Mexico, roam all of Europe, and inhabit parts of North Africa and the Middle East.
"If we want to predict how a warming climate will affect these bears, we can't leave out these natural areas of their range," Søren Faurby, study co-author and biologist at the University of Gothenburg in Sweden, said in a statement.
The months-long project involved piecing together information from various different datasets. To determine a species' "natural range" (i.e. what it would be without human meddling), the team collected evidence from old maps and museum records.
Perhaps most importantly, the project also involved mapping animals already driven to extinction by human activity. To do so, the researchers plugged DNA data and evidence gathered from archaeological digs into a computer algorithm, which then predicted where those animals would exist today.
While elephants, cheetahs, and other larger animals are most commonly found in Africa and parts of Asia, this wasn't always the case – as this new research shows. And if it wasn't for Homo sapiens' propensity to hunt or drive these species to extinction by other means, big mammals – like the Tasmanian tiger, the largest carnivorous marsupial of recent times, and the cave bear – would, in all probability, still be found across the globe today.
"If we are studying global patterns of biodiversity, we really need to start considering species like the Tasmanian tiger that was hunted to extinction less than 100 years ago, a mere eyeblink in geological time," Matt Davis, co-author and paleontologist at Aarhus University, Denmark, explained.
"This is the first time we've been able to comprehensively include extinct species like the Tasmanian tiger or the woolly mammoth as well as account for human-induced regional range losses among extant species in such a large database, and it's really changing our beliefs about what is 'natural' or not," Faurby added.
"We are already using the database to quantify and map human-induced biodiversity deficits and assess restoration potential across the globe."