As if rising sea levels, raging wildfires, and toxic air pollution weren’t enough, research has shown that humanity is currently literally shrinking wildlife.
Several studies have come to the same conclusion: climate change and other human activities are causing animals of the same species to become smaller and larger animals to decline as much smaller animals thrive.
Researchers from the UK have suggested that this may pose a threat to deer and eagles; while rats and parrots continue to thrive.
Similar changes are likely to occur under UK coastal waters. Ancient fossils from limestone outcrops on the British coast, railway cuts, quarries and quarries have provided valuable insights into how global warming has reduced UK marine life in the past and how it is likely to happen in the future.
A period of global warming 94 million years ago reduced the size of sea urchins, sharks, burrowing crustaceans and other sea creatures that inhabited Britain’s coastal waters, according to an analysis of fossils from chalk quarries in southeast England that once lay underwater. . I can reveal.
Conversely, research shows that an ancient period of global cooling led to larger sea creatures.
And a separate new study found that climate change has reduced marine life over the past 200 years.
Professor Richard Twitchett of the Natural History Museum, who led all three research projects, said: “For marine animals, the evidence for past warming is clear: most animal species that have survived periods of global warming are smaller than before, and body sizes increase again when conditions are normalized.
“It occurs in both invertebrates and vertebrates, with and without a mineralized skeleton, and in animals living in the water column or on the seabed. There is no reason to believe that current or future warming events will be different.”
The museum’s large collection of animal fossils ranging from 80 to 100 million years old provided the basis for two studies.
These include many of the rarer top predators, such as sharks, “in sufficient numbers for worthy quantitative studies,” said Professor Twitchett, who analyzed the fossils with his students.
“I am very pleased with these results,” he said. I. “So far, my students have demonstrated the miniaturization of sea urchins, burrowing crustaceans, and a species of shark related to modern goblin sharks.
“Interestingly, the higher parts of the Cretaceous also show significant cooling, and there we see the opposite pattern – an increase in body size in marine organisms, including giant ammonites and larger sharks.”
His third study on climate change over the past two centuries used animal specimens from the museum “to see if there is evidence of a decrease in the size of marine animals over the past 200 years with the Anthropocene.” [human] before training.”
“In groups that use people for food, many studies have already shown a reduction in size,” said Professor Twitchett.
“However, my student showed that even in some groups where there is no direct human influence, we see a reduction, suggesting that this is a response to climate change.”
The main reason for the decline in the number of marine species is a double whammy: warmer water contains less dissolved oxygen, on which animals depend for their metabolic energy, and at the same time, the amount of energy animals need to function increases, that is, it becomes more plentiful that be less.
Another new study from University College London found that human land development also discriminates against larger species.
Why is it harder for large animals to interact with humans?
Adrian Lister of the Natural History Museum said: “The extinction of ancient mammals is sometimes thought to be due to over-hunting of large mammal species by Paleolithic hunters. But there is no doubt that climate change has played an important role.
“If you can use many different sources for energy, you don’t have to be the most efficient or the most competitive species. Slower species are better competitors and theoretically more energy efficient, but at the cost of very specific habitat requirements.
“Whatever the cause, there is evidence that the lower reproductive capacity of large species is an important factor in their sensitivity to environmental issues. The rest of the fauna is on average smaller in body size, although nothing has actually “decreased”.
The focus is on development when natural landscapes are deliberately turned into agricultural land or when climate change turns them into badlands. It studied the impact on 1072 populations of birds, mammals and reptiles from the UK and Europe, Asia, Africa, the Americas and Australasia between 1992 and 2016.
It compared the survival rates of so-called “fast-living” species, which live shorter lives, reproduce quickly and tend to be smaller, with “slow-living” animals, which live longer and tend to be larger.
The researchers found that “globally, in areas of rapid expansion of agricultural land or bare soil, fast-moving species have increased in numbers while slow-moving species have declined in recent decades.”
They warned that there could be significant differences within these general trends. “Not all animal populations respond equally well to climate and land use changes, as some groups are more vulnerable than others,” said lead author Dr. Gonzalo Albaladejo Robles of University College London and the Institute of Zoology. I.
But he added: “As humans have more and more influence on global ecosystems, we may be seeing a shift in the makeup of animal communities in many areas as some slow-moving animals disappear while fast-moving ones continue to thrive.”
In the UK, results show smaller animals such as black and brown rats, monk parakeets, arctic hares and stoats outperform larger animals such as white-tailed eagles, red deer, ospreys and guillemots.
“It can be said that species listed as slow are more likely to be more affected by land use and climate change than species listed as faster,” the doctor said. Robles.
“However, species responses are complex, and other factors not mentioned in my study could lead to rapid or slow declines in species populations.”
The results also show that larger animals will fare worse than smaller ones due to other forms of human development such as buildings and other infrastructure.
“In general, human use of land, and hence its expansion, favors fast-moving species and disadvantages slow-moving species,” the researchers note.
“Everything indicates that the average size of animals is likely to decrease in the future,” the doctor said. Robles.
Source: I News
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