We share our planet with millions of plants and animals.
Author
- David Lindenmayer
Distinguished Professor of Ecology, Fenner School of Environment and Society, Australian National University
This variety of life is known as biodiversity , a term encompassing everything from microscopic genes to entire ecosystems , such as deserts and vibrant coral reefs.
Places that support a wealth of species are known as ” biodiversity hotspots “. South America’s tropical Andes region – which has the world’s largest variety of amphibian, bird and mammal species – and the coastal forests of eastern Australia are just two examples.
Our new study suggests biodiversity hotspots are emerging in new, and in some cases unexpected, locations.
So why is this happening? And what does it mean for species across the globe?
Spotting a hotspot
Scientists generally agree there are 17 megadiverse countries worldwide, including Brazil, Indonesia, India and Australia. But even within their borders, there are regions that are particularly rich in species, such as the Amazon rainforests of Brazil and Ecuador.
Finding biodiversity hotspots relies on scientifically describing the key characteristics of each individual species that occurs in a particular place. This includes identifying the features that distinguish a new species from all other known species, before giving it a formal and unique Latin scientific name.
The problem is there are many species western science hasn’t even discovered. Research suggests about 80% of the world’s plants and animals are yet to be formally studied. This is true even for well-researched vertebrate groups such as mammals, birds and reptiles.
For instance, each year researchers discover more than 2,000 new vascular plant species, which are distinguished by a range of features such as their special tube-like tissues . However, studies show as many as 100,000 more plant species remain unknown to science. And of the mammal species we know about today, one in ten were discovered only after the 1990s.
Shifting locations
Our research suggests the discovery of new species is altering where we understand biodiversity hotpots to be located, including here in Australia.
In our new study , we examined discoveries of land-based species over 100 years to find out how they may have reshaped our understanding of global diversity patterns.
To do this, we identified when and where species were first found for each decade between 1920 and 2020. In the end, we collected data on more than 9,700 species of birds, 5,200 of mammals, 8,600 of reptiles and 7,200 of amphibians.
Our results suggest we’ve found and named nearly 40% of land-dwelling species over the past century. Most of these species discoveries have occurred in tropical regions such as the rainforests of Brazil, Ecuador and New Guinea. This aligns with the well-established pattern that polar areas, such as the Artic and Antarctica, typically have fewer species than tropical locations.
New Guinea’s montane forests – where plants grow on the slopes of mountains – had high discovery rates of new mammal species. When it comes to reptiles, Australia is a standout. The number of known reptiles nationwide has more than doubled over the past century, rising from 376 species in 1920 to 933 in 2020.
Our research suggests discoveries of new species are leading to the emergence of several biodiversity hotspots including Indonesia, the central Andes of South America and the island nation of Madagascar.
One-third of areas previously known for their rich amphibian life have been replaced by new amphibian hotspots, including the tropical forests of south-east Asia and the montane forests of the Andes. We observed a similar trend in reptiles. Roughly 20% of formerly recognised hotspots are now overshadowed by our new knowledge of regions with even higher reptile diversity, including the savannas and shrublands of northern Australia.
Why this matters
Understanding where biodiversity hotspots are, and how they are changing, is vital for conservation.
Our research suggests emerging biodiversity hotspots for reptile and frog species are increasingly in cooler environments, including the little explored cloud and montane forests of the Andes. However, by making these forests drier and warmer , climate change is threatening the survival of many newly discovered species.
These emerging hotspots are also vulnerable to deforestation and land clearing. Without major and immediate conservation action, the species living in these places will disappear, potentially before scientists even discover them. This is known as a ” dark extinction “.
Protecting our biodiversity hotspots matters. But we cannot save species we don’t even know about, so we must invest in field surveys and taxonomy projects that lead to new species discoveries. Otherwise, these rich ecosystems will keep losing species that science never had the chance to name.
