Some warm-blooded animals are experiencing changes in their body forms, likely in response to the pressures of climate change. The conclusion comes from a new review of existing research.
Animals are getting bigger beaks, legs and ears that allow them to better regulate their body temperature as the planet gets warmer.
Birds are particularly affected, according to Sara Ryding, a researcher at Deakin University in Australia and one of the authors of the research published on Tuesday (7) in the journal “Trends in Ecology & Evolution”.
The biggest changes in the size of parts (or external appendages) of more than 30 animals studied have occurred among some species of Australian parrots, whose beaks have increased by 4% to 10% on average since 1871.
“That means animals are evolving, but it doesn’t necessarily mean they’re dealing with climate change. We can see that some species have had an increase in the size of their appendages so far, but we don’t know if they will be able to keep up with the worsening climate crisis,” Ryding said.
“We also don’t know if these shape changes really help survival [e, portanto, são benéficas] or not.”
According to the researcher, the phenomenon of shape change should not be seen as positive, but rather alarming, “because climate change is leading animals to evolve like this, in a relatively short period.”
Ryding said the changes were subtle and unlikely to be immediately noticeable, but could be “functionally important.”
While climate warming was a “compelling argument” as the driving force behind these shape-shifting changes, the study said it was difficult “to establish causality with confidence” given the multifaceted effects climate change has on the environment.
Smaller bodies, larger appendages
Within an animal species, individuals in warmer climates have larger appendages, such as wings and beaks – a pattern known as Allen’s Rule, with the largest surface area allowing animals to control their temperature more easily, as the study recalled.
At the same time, body size tends to shrink, as smaller bodies retain less heat.
In the United States, another recent study, this one with 70,716 migratory birds representing 52 species, showed that they have gotten smaller in the last four decades, but with a larger scale.
All of the birds studied died upon reaching tall buildings in Chicago during the migration and were collected by the city’s Field Museum.
“Both studies look at how animals respond to climate change by altering their surface area relative to volume,” explained Ryding.
Although most research on morphological changes over time has focused on birds, the second study also found that shrews and bats increased their relative sizes of ears, tail, feet and wings.
More research on different species and different ecosystems is needed to determine the magnitude of the phenomenon, possibly helping to predict which species might change shape in the future.
“Previous studies have shown cases where shapeshifting is taking place, but they have focused on individual species or groups. Our review article combines all of this to show how pervasive this phenomenon seems to be,” Ryding said.
(Translated text. Click here to read the original in English).