Many animal appendages, such as bird beaks and mammalian ears, can be used to dissipate excess body heat.
Photo : Pixabay/Alexas_Fotos
As the climate changes, warm-blooded animals also change. Warmer temperatures are causing many species to try to stay cool through various evolutionary adaptations: bigger ears, bigger bills, longer legs.
« [A]animals must also adapt to these [climatic] changes, but it’s happening on a much shorter timescale than what would have happened for most of evolutionary time, ”says Sara Ryding, a researcher at Deakin University in Australia who describes these adaptive changes in a new article. .
“The climate change that we have created is putting a lot of pressure on them, and while some species will adapt, others will not,” warns Ryding.
As part of their thermoregulation, blood-savvy animals adapted to warmer climates have larger appendages in a phenomenon known as “Allen’s Rule”, which was first formulated by American zoologist Joel. Asaph Allen in 1877 and states that climate influences the length and shape of animals. body and appendages.
Warmer climates tend to produce slender creatures with long limbs, whose morphology allows them to stay cooler more efficiently, while colder climates prefer stockier animals and shorter limbs, which allows them to better retain body heat. Now, in the face of rising temperatures, several species are “changing shape” over generations to sport longer limbs and larger appendages, Ryding notes.
“Many animal appendages, such as bird beaks and mammalian ears, can be used to dissipate excess body heat,” she writes. “We find that there is widespread evidence of ‘shape change’ (changes in the size of appendages) in endotherms in response to climate change and associated global warming. “
These morphological changes have been occurring observably for a century among a wide range of species in large geographic areas, the scientist explains.
The trend has been particularly noticeable in birds such as the Australian parrot species which have on average increased their beak size by 4% to 10% since 1871, around the time Allen’s rule was postulated for the first time. However, mammalian species such as wood mice and masked shrews also have longer tails and legs than before.
“The increases in appendage size that we’re seeing so far are pretty small – less than 10% – so the changes are unlikely to be immediately noticeable,” Ryding said. “However, prominent appendages such as the ears are expected to increase – so we might end up with a live Dumbo in the not-so-distant future. “
However, this morphological trend may not bode well for many animal species as the climate continues to warm over the next decades.
“Shape change doesn’t mean animals are dealing with climate change and everything is fine,” Ryding emphasizes. “It just means that they evolve to survive there – but we don’t know what the other ecological consequences are of those changes, or in fact that all species are able to change and survive. “