Global warming is changing our planet. It makes hurricanes more violent, makes fires more frequent, and makes rivers dry up. Now, scientists have discovered that climate change has also turned animals into shapeshifters. Many creatures are changing the size and shape of certain parts of their bodies. Some have grown larger wings, some have grown longer ears, and some have grown larger beaks. Scientists say that these changes do not happen randomly. Animals are adapting to climate change in order to better regulate their body temperature-mainly to dissipate heat.
A team of scientists from Deakin University in Australia and colleagues at Brooke University in Canada tracked and analyzed how more than 30 animals changed their shapes to respond to rising temperatures in different time frames. In the process, they sorted out nearly 100 related studies, some of which were based on field trips and laboratory experiments, and some were based on a large number of museum collections-animal specimens classified, measured and preserved by the museum decades ago. Among them, some research samples can be traced back to one or two centuries ago. The researchers published their results in the journal Trends in Ecology and Evolution.
”Their efforts are admirable,” said Ben Wenger, an ornithologist at the University of Michigan. Wenger did not participate in this project, but is also engaged in related research. These findings reveal from a new perspective how warm-blooded animals on the earth respond to climate warming.
Unlike humans, warm-blooded animals in the wild can enjoy the coolness brought by air conditioning. They can only rely on their own regulation to avoid hyperthermia. Sara Redding, the initiator of the research project, explained that they release heat mainly through their appendages. Birds’ paws and beaks can dissipate heat; bats can release heat through their wings; small animals like mice can also use their tails to dissipate heat; elephants use huge ears to keep cool. In some videos, when elephants are walking on the beautiful African savanna, their ears will flap back and forth regularly. They rely on this method to release excess heat into the air. “Elephants dissipate heat through their ears is a well-documented fact.” Redding said.
Redding’s team found that over time, Australian parrots’ beaks grew larger, bats grew larger wings, European rabbits grew longer ears, and mice’s tails grew longer. “Since parrots are the observation objects of many research projects, it would be better to take them as examples.” Redding said, “Because there are a large number of bird specimens and document records in the museum, its history can be traced back to the 19th century, and some specimens are even more Ancient.” Thanks to these data, Redding’s team found that the surface area of the parrot’s beak has increased by 4% to 10% since 1871. In addition, through the analysis of museum bat specimens (including specimens with a history of 65 years), the team found that since the 1950s, the size of bats’ wings has increased by more than 1%.
Researchers claim that this morphological change of animals makes sense. In biology, there is a well-known “Bergman’s Law”, that is, animals living in cold climates are usually larger and thicker than those near the equator in order to better conserve body heat. The law is named after the 19th-century biologist Carl Bergman, who first described this biological phenomenon in 1847. Thirty years later, another biologist, Joel Assaf Allen, further expanded this concept. He pointed out that animals that adapt to cold climates have shorter appendages-which can effectively prevent heat loss. According to a similar principle of body temperature regulation, the appendages of warm-blooded animals in hot climates will become larger (relative to their body size).
Larger appendages mean that a larger vascular system can be generated, thereby accelerating blood circulation and releasing more body heat. Redding explained: “According to Allen’s law, this means that when an animal pumps blood into an appendage, there is a larger surface area to help dissipate heat.” This is roughly similar to how an apartment radiator works: a larger surface area The radiator will release more heat to the room.
Larger appendages such as beaks, ears, tails, and wings can help animals dissipate heat. It can be seen in the thermal imaging photos of parrots that their beaks and claws emit a bright yellow light, which is the heat released by the beak and claws.
The elephant radiates heat by fanning its ears.
Thermal imaging photos show that parrots release heat through their beaks and claws.
Redding’s team also conducted various field studies at the same time. One of the studies continued to document the changes in the beaks of finches in the Galapagos Islands from 2003 to 2011. Researchers found that as the temperature increased, the beak of the finches became larger. “The finches in the Galapagos Islands will increase their beaks based on the temperature of the previous year, and the magnitude of the changes will vary,” Redding said. The team’s other set of data comes from European rabbits, who were brought to Australia and lived in different climate zones. Over time, those rabbits that live in hotter areas grow longer ears. Riding said: “This is a very interesting example of how animals can respond to differences in ambient temperature after being introduced to other regions.” The
research team also found that Japanese quails that grew up in a laboratory environment with a higher temperature Quails have longer beaks than those grown in typical habitats, and they only need one generation to adapt to environmental changes. In the same way, mice grown up in the laboratory have longer tails. Redding pointed out that this is much shorter than the deformation found in museums and field studies, which shows that animals can indeed adapt to the environment very quickly.
However, researchers are not sure whether this deformation can be considered a good phenomenon. “It’s hard to say what the consequences are.” Wenger said. “It depends on whether these adaptive changes can keep up with other environmental changes and how they will affect foraging and avoiding predators.”
If larger ears or The beak can help animals dissipate heat and prevent them from heatstroke or death, which is a good thing. But some changes may interfere with the foraging ability of some animals. For example, for birds that feed on nectar, it is important to have a small and narrow beak. Ledding said: “If a hummingbird’s beak becomes wider and wider, it may be too large to absorb nectar and nutrients effectively.” This will cause it to become malnourished. Therefore, Riding believes that deformation does not mean that animals can cope with climate change well, but that animals are evolving to withstand the consequences of climate change. In the long run, we still don’t know whether this is beneficial to the survival and reproduction of animals.
The enlarged beak may affect the hummingbird’s intake of nectar.
European rabbits living in hotter areas have longer ears.
Deformation does not mean that animals can cope with climate change well, it just means that animals are evolving to withstand the consequences of climate change.
But one thing is certain is that rising temperatures in the future will make more animals become shapeshifters. Raymond Danner, an evolutionary ecologist at the University of North Carolina at Wilmington, believes that the term “transformation” is not only appropriate but also vivid. Danner was not involved in this research, but did similar work. He said: “The term’transformation’ is a good example of how animals respond to environmental challenges over time.” He added that there is more and more evidence related to this topic. The research integrates relevant data well. “Perhaps more importantly, her team showed how to design research by reanalyzing the data set, so that we can better understand the future animal deformation.”