Global warming is already one of the most talked about issues of the year. Last month, the UN’s Intergovernmental Panel on Climate Change (IPCC) released a report on the different temperature scenarios the world can expect in the coming decades. And the animals didn’t even have to read the report to know that the situation is serious – they show it with their own bodies.
A research published in the journal Trends in Ecology & Evolution shows that some species are altering their body shape to cope with climate change. The research team noticed that the animals’ appendages (structures that protrude outside the body, such as beaks, tails and ears) are increasing in size. This is an evolutionary strategy to cool the body and combat external heat.
Many warm-blooded species (such as birds and mammals) use their appendages to regulate their internal body temperature. African elephants, for example, pump blood into their ears and shake them to dissipate heat. Birds, in turn, divert blood flow to the beak.
The first to observe this relationship was the American zoologist named Joel Allen, in the 1870s. He noticed that animals from warm climates tended to have larger limbs compared to those from cold climates. The larger members provide a greater surface for contact with the environment – and therefore more heat dissipation.
Just think about what you do when you’re cold: try to curl up and bring all your limbs close to you to avoid losing heat. Best for animals in warm climates, then, is to stick their limbs outward. The relationship between climate and member size became known as the Allen Rule.
The new study looked at body change primarily in birds. The beak of the gang cockatoo (callocephalon fimbriatum) and the gray parrot (Psittacus erithacus) are 4% to 10% larger when compared to measurements taken in 1871. This “growth” is not a choice of animals, but a result of evolution and adaptation to the environment over the last 150 years. Birds with slightly larger beaks are better able to dissipate heat and are more likely to survive by passing on their genes to their offspring.
Birds are the most affected, but not the only ones. Scientists have also recorded increases in bat wing size, field rat tail length and also the size of the legs and tails of masked shrews. In summary, the problem already affects different species and from different locations around the globe.
It’s remarkable that species are evolving to survive, but that doesn’t mean they all will. Some birds, for example, need to maintain the shape of their beaks due to their feeding style. Without being able to feed or cool the body, some will eventually die – which could intensify the extinction of species in the future.
Mapping the most vulnerable species is essential for environmentalists to scale up conservation efforts. Even so, the researchers make it clear that the simplest way to preserve the lives of these animals is to avoid the intensification of global warming.