Climate change has long been thought to shrink all animals such as birds, fish and even insects, but due to all free food from humans, urban animals are larger than rural animals. You may be fat.
For over 80 years, researchers have examined records of over 140,000 body sizes in 100 North American mammal species and found that urban animals are growing. This twists the long-standing belief known as Bergmann’s rule, despite rising temperatures due to climate change.
Bergmann’s rule states that animals in warm climates are smaller than animals in cold climates.
“Theoretically, the effects of these heat islands should make the animals in the city smaller, but we couldn’t find any evidence that this was happening in mammals,” said a postdoctoral fellow at the Florida Museum. Maggie Huntaku said in a statement.
“This treatise is a good discussion of why Bergmann’s rule and climate alone cannot be assumed to be important in determining animal size.”
New studies suggest that urban animals can grow and become fat due to free food from humans
Researchers have analyzed about 140,000 body sizes from 100 mammalian species in 80 years.Experts have discovered that mammals in cities tend to grow regardless of temperature.
According to the Environmental Protection Agency, the aforementioned “heat island effect” is due to the fact that urban buildings and roads trap heat and at the same time release more heat.
Daytime temperatures are 1-7 degrees higher than the surrounding area, and nighttime temperatures are 2-5 degrees higher.
Earlier this month, the United Nations reported that the planet would rise 2.7 degrees Fahrenheit by 2040, ten years ahead of expectations.
Researchers have created a model that shows how the climate and population density of a region affected the size of mammals.
Urban mammals (the most densely populated mammals) tend to grow regardless of temperature, and living in the city may have several benefits, including more food, water, and shelter. Suggests that
As the temperature dropped, most species gained length and weight.
However, urban mammals (the most densely populated mammals) tend to grow regardless of temperature, and even if there are challenges, there are some challenges to living in the city, such as increased food, water and shelter. There may be advantages of.
Hibernating animals contracted significantly due to higher temperatures than non-hibernating animals
Some animals that use hibernation or diapause, a temporary method of slowing metabolism and lowering body temperature, significantly shrunk when experiencing elevated temperatures than animals without these properties.
Urban animals may enjoy “selective advantages” over rural animals as the climate heats up.
“That wasn’t what we expected,” said Robert Guralnick, co-author of the study and curator of biodiversity informatics at the Florida Museum, in a statement.
“But urbanization represents this new turmoil in natural landscapes that didn’t exist thousands of years ago. It’s important to recognize that it has a huge impact.”
He went on:’When thinking about what will happen to mammals’ body sizes in the next 100 years, many consider it to be the cause of global warming making animals smaller. What if it’s not the maximum effect? What if urbanization leads to fatter mammals? ”
Surprisingly, not all animals responded equally to human-induced environmental changes.
At this time, it is unclear what the impact will be on mammals in cities that eat human food, and further research is needed at this point.
Those using hibernation or dormancy, a temporary method for slowing metabolism and lowering body temperature, shrank significantly more when the temperature rose than those without these properties.
“I thought that species that use dormancy or hibernation could hide from the effects of adverse temperatures, but in reality they seem to be more sensitive,” said Huntak.
As the climate continues to rise, urban animals may also enjoy “selective advantages” over rural animals, Guralnick added.
“This is related to our thinking about the management of suburbs and urban areas and our wilderness 100 years later.”
At this time, it is unclear how it will affect mammals in cities that eat human food, and further research is needed at this time.
“Changing the size can change the whole lifestyle,” explained Huntaku.
This study was published in Communications Biology earlier this week.
Species Shrinkage: Experts Predict Global Warming Causes Organism Shrinkage
Recent studies in Canada have shown that beetles in the region have shrunk over the last century.
By examining eight species of beetles and measuring past and present animals, we found that some beetles adapted to shrinking body size.
The data also showed that the large beetles were shrinking, but the small beetles were not.
About 50 million years ago, the Earth warmed up to 3 degrees Celsius (5.4 ° F), resulting in a 14 percent reduction in animal species at the time.
Another warming event about 55 million years ago (called the Paleocene-Eocene Heat Maximum (PETM)) warmed the Earth to 8 degrees Celsius (14.4 ° F).
In this example, the animal species at that time were reduced by up to one-third.
Mammoths were victims of increased hunting due to climate warming, habitat shrinkage, and early population growth, and were endangered along with many large animals.
Body size reductions can be seen from several global warming events.
As global temperatures continue to rise, the average size of most animals is expected to decline.
In addition to global warming, the number of large animals in the world is declining dramatically.
The so-called “Megafauna” is a large animal that becomes extinct. Due to their long lifespan and relatively small population, they cannot adapt to rapid changes as smaller animals that breed more frequently.
Often hunted for trophies and food, large animals such as the Masterdon, Mammoth, and Western Black Rhinoceros, which were declared extinct in 2011, are on the verge of extinction.