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Extreme Climate change According to a leading biologist, evolution is occurring so quickly in animals that it is creating distinct changes that can easily be measured in a matter weeks.
From Caribbean lizards growing larger toe pads to grip trees more tightly as hurricanes become more frequent, to shrinking squid, to larger damselfly wings in Britain – the way nature is adapting is confounding Darwin’s beliefs about the speed of evolutionThor Hanson agrees.
A former park ranger in Alaska, he argues that global warming may have had an even bigger impact on nature than it has on the weather – even though the changes may not be as visible to the person on the street.
He also mentions the global movement in wildlife as a result of a warming planet, and expects hammerheads to be a regular part of the UK’s coastline.
These changes were revealed by the American academic and author, Hurricane Lizards and Plastic Squid – How the Natural World is Adapting to Climate ChangePublished this week:
Hanson says that animals don’t just move on from their old habitats. They also change their behaviours by adopting new diets.
Perhaps most importantly, some people have even evolved to adapt to the new world order that is governed by the survival of fittest.
“I wasn’t surprised to find that climate change is driving evolution but I was surprised you would be able to measure it in such a short period of time – and measure it definitively,” says Hanson, who lives on the island of San Juan between the US and Canada and has worked with bears in Alaska and gorillas in Uganda.
“Charles Darwin was a strong believer of evolution as this slow and incremental process of change. But what we’re realising is steps in that process can be rapid – you can measure distinct evolutionary change in just six weeks, as happened with the Caribbean lizard.”
How hurricanes have changed lizards
Thor Hanson recounts how scientists discovered the rapid evolutionary response of lizards while studying the tiny anole lizard, which lives on the Turks-and- Caicos islands in The Caribbean.
Two categor-four hurricanes ravaged the area, and the scientists realized that this was an excellent opportunity to study the effects of extreme weather on lizards.
The surviving lizards were found to have significantly larger toe pads and stronger front leg muscles for gripping tightly to the tree trunks and branches they were holding on to during high winds.
This trait was passed down to the next generation until the front limb pads grew by 9.2 percent.
The lizards also evolved front legs that are 1.8 per cent longer, and stronger, which helps further with gripping back legs that are 6 per cent shorter, “apparently to help reduce drag in the highest winds,” says Hanson.
Scientists have found the same evolution in anole-lizards in the Caribbean in response to hurricanes.
Meanwhile Humboldt squid, referred to in the title of his new book, have shrunk in half, shortened their lifespan and reproduce much earlier to get around the difficulties posed by heat stress in the warming ocean – as smaller animals lose heat faster because they have a larger surface-area-to-volume ratio.
“Climate change doesn’t speed up the process of evolution, per se. But it does create conditions where rapid evolution is more more likely,” he says.
“Extreme weather events, timing changes, and other climate-driven stressors set the stage for natural selection to act upon variable traits – like lizard toe pads. Simply put, when environmental conditions change, species respond, and part of that response will be evolutionary.”
Hanson says that plants are also adapting to climate changes. “Bloom time, budburst and other spring events are rapidly advancing as temperatures warm,” he says. “Wild daffodils in the UK now bloom 40 days earlier than they did in the 1950s, a trend echoed to varying degrees by everything from lilacs to snowdrops to laburnum.
“Timing mismatches are becoming common in spring. Many trees are leafing out earlier, for example, casting shade over woodland wildflowers like bluebells that used to enjoy weeks of full sun.”
A separate study by Cambridge University found that plants in the UK flower on average a month earlier than before the industrial revolution.
The researchers analyzed more that 400,000 records of 406 species of plants going back to 18th century.
And they observed that the average first-flowering date from 1987 to 2019 – a period that coincides with global warming caused by human activity – was a month earlier than the average first-flowering date from 1753 to 1986.
Lead author Professor Ulf Büntgen, from Cambridge’s department of geography, said: “The results are truly alarming, because of the ecological risks associated with earlier flowering times.
“When plants flower too early, a late frost can kill them – a phenomenon that most gardeners will have experienced at some point. The bigger danger is ecological mismatch.
“Plants, insects, birds and other wildlife have co-evolved to a point that they’re synchronised in their development stages. A certain plant that flowers attracts a certain type of insect which attracts a different type of bird.
“But if one component responds faster than the others, there’s a risk that they’ll be out of synch, which can lead species to collapse if they can’t adapt quickly enough.”
Hanson’s book looks at how fast some responses to climate change have been. “Seeing how widespread the responses are in nature shows us how fast this is actually happening and how extreme it already is,” he says.
“The response of plants and animals is so great that it is comparable, or possibly even exceeds, changes in the weather.
“Evolution is ongoing – it’s happening all the time and all around us, usually in a slow way we can’t measure or perceive. But if you’re in the right place at the right time, you can see measurable steps play out.”
Climate change is also causing significant changes in animal and plant behaviour in the UK, both on land and in rivers. “Plants and animals across the country are shifting their ranges as temperatures warm, seeking out the climate conditions they’re used to” says Hanson.
“Hundreds, if not thousands, of species are affected, from familiar backyard creatures like robins and great tits to lesser known things like ocean plankton, some of which have shifted over 1,100 kilometres north in less than 50 years.”
“Dragonflies are expanding northward by an average of 50km every decade, while everything from spiders to birds to ground beetles have been clocked shifting at more than 30km per decade.”
New arrivals from the south are also being driven by climate-driven range shifting. Hanson points out that little egrets were the first to establish breeding colonies in 1996. They are now common. Breeding residents include quail, cattle egrets and purple herons.
“Tree bumblebees and ivy bees were first sighted in England and Wales in the early 2000s,” he says. “Over 30 new moth species have fluttered in since 2000, as well as new damselflies, spiders, and flies.”
He expects a wide range of climate immigrants to arrive in the UK “in coming years, from black kites and zitting cisticolas (a grassland bird) to hammerhead sharks”.
Currently, there are changes among UK residents. “Damselflies and bush crickets in Britain, for example, now display larger wings at the northern, expanding edges of their ranges, an evolutionary adaptation,” says Hanson.
“And the brown argus butterfly has changed its diet, leaving rockrose behind and now laying its eggs on the wild geraniums common in the habitats where its range is expanding.”
Hurricane Lizards and Plastic Squid – How the Natural World is Adapting to Climate Change, by Thor Hanson, is published by Icon Books at £20
