Extreme weather events such as prolonged drought and heavy rain are becoming more common as the global average temperature rises – and it will only worsen in the decades to come. How will the planet’s ecosystems react?
“This is the big issue and the context of our study”, said the biologist John Jackson, who along with fellow biologists Christie Le Coeur from the University of Oslo and Owen Jones from the University of Southern Denmark, is the author of a new study, published in eLife.
John Jackson is now at Oxford University but was at the University of Southern Denmark when the study was carried out. Owen Jones is Associate Professor in the Department of Biology at the University of Southern Denmark.
Llama, moose and elephant
In the study, the authors analyzed data on fluctuations in the population of 157 mammal species from around the world and compared them to weather and climate data from the time the animal data was collected. For each species, there are 10 years or more of data.
Their analysis gave them insight into how populations of animal species have coped with extreme weather: have they become more or less numerous? Did they have more or fewer offspring?
“We can see a clear trend: animals that live long and have few offspring are less vulnerable when extreme weather hits than animals that live a short time and have many offspring. Examples are llamas, long-lived bats, and elephants versus mice. opossums and rare marsupials like the woylie,” said Owen Jones. extreme weather conditions:
African elephant, Siberian tiger, chimpanzee, large horseshoe, llama, vicuna, white rhino, grizzly, American bison, klipspringer, Schreibers’ bat.
Most affected by extreme weather conditions:
Azara mouse, olive mouse, elegant fat-tailed mouse opossum, Canadian lemming, tundra vole, arctic fox, ermine, common shrew, woylie, squirrel arctic land.
Rapid fall – but also rapid increase
Large, long-lived animals are better able to cope with conditions such as prolonged drought their ability to survive, to breed and raise their offspring are not affected to the same extent as small, short-lived animals. They may, for example, invest their energy in offspring or simply wait for better times when food gets tough.
On the other hand, small, short-lived rodents have more extreme population changes in the short term. In case of prolonged drought, for example, much of their food base can disappear more quickly: insects, flowers, fruits, and they are left to starve because their fat reserves are limited.
The populations of these small mammals can also explode to take advantage of improved conditions because, unlike large mammals, they can produce many offspring.
Not the same as extinction risk
“These small mammals react quickly to extreme weather conditions, and it goes both ways. Their vulnerability to extreme weather conditions should therefore not be equated with an extinction risk,” said John Jackson.
It also recalls that the ability of an animal species to resist climate change should not be isolated when assessing the vulnerability of the species to extinction:
“Habitat destruction, poaching, air pollution and invasive species are factors that threaten many animal species – in many cases even more than climate change”, he underlined.
Animals about which we do not know much
The researchers’ study does not only give a insight into how these 157 specific mammal species are responding to climate change in the here and now. The study may also contribute to a better general understanding of how the planet’s animals will respond to ongoing climate change.
“We predict that climate change will bring problems more extreme weather in the future. Animals will have to deal with these extreme weather conditions as they always have. Thus, our analysis helps predict how different animal species might react to future climate change based on their general characteristics – – even though we have limited data on their populations,” said Owen Jones.
An example is the woylie, a rare Australian marsupial. Biologists don’t know much about this species, but because it shares a mouse-like lifestyle — that is, it’s small, lives a short time, and reproduces quickly — we can predict that it will react to extreme weather conditions. in the same way as mice.
Entire ecosystems will change
“In the same way, there are many animal species of which we do not know much , but whose reaction we can now predict”, explained John Jackson.
Thus, the researchers expect that the ability of different animal species to adapt to the climate change is related to their life strategy, which can help us predict ecological changes:
As habitat suitability alters due to climate change , species may be forced to move to new areas as old areas become inhospitable. These changes depend on species life strategies and can have significant impacts on ecosystem functioning.
The work was supported by Impartial Investigation Fund Denmark.