A warming environment speeds up the rate of living in cold-blooded animals, causing them to die younger.
Ectotherm animals depend on external sources for their body heat because they lack the ability to retain the heat generated by their own metabolism. So when it is cold outside, the temperature of these so-called “cold-blooded” creatures drops and their metabolism slows down. When it is hot, the opposite happens.
One might assume then that warming temperatures brought on by climate change will benefit many ectotherm animals, which include lizards, snakes and amphibians. They will become more active and less at the mercy of changing outside temperatures.
Others have posited, however, that faster metabolism triggered by warmer weather will cause accelerated aging in these animals, leading to shorter lifespans in them.
According to a dominant century-old theory called “rate of living,” the faster the metabolic rate of an organism, the shorter its lifespan will become. That is why fast-living creatures like mice have lifespans of only a few years whereas some slow-living turtles can go on for well over a century.
A team of researchers from Israel’s Tel Aviv University and Queen’s University Belfast, in Northern Ireland, decided to see what will likely happen to cold-blooded animals if their metabolism is speeded up by warming temperatures. To do so, they analyzed data from more than 4,100 species of land-based vertebrates.
What they have found, as they document in a new study, is that a warming environment does speed up the rate of living in cold-blooded animals, causing them to age faster and die younger.
“The link between lifespan in cold-blooded animals (amphibians and reptiles) and ambient temperature could mean that they are especially vulnerable to the unprecedented global warming that the planet is currently experiencing,” said Gavin Stark, a PhD student at Tel Aviv University who was the study’s lead author. “Indeed, if increasing ambient temperatures reduces longevity, it may make these species more prone to go extinct as the climate warms.”
What this could mean is that cold-blooded animals might be especially at risk of going extinct in a warmer world. “Now we know that the life-expectancy of cold-blooded vertebrates is linked to environmental temperatures, we could expect to see their lifespans further reduced as temperatures continue to rise through global warming,” noted Daniel Pincheira-Donoso, a lecturer in evolution and macroecology at the School of Biological Sciences at Queen’s University Belfast.
Ectotherm animals are already a highly threatened group, according to conservationists, with some 20% of the 10,000 or so species of lizards, snakes, turtles, crocodiles and other reptiles facing the prospect of extinction. Ongoing climate change will deal further blows to many of these species.
“We need to further develop our understanding of this link between biodiversity and climate change,” Pincheira-Donoso says. “Only armed with knowledge will we be able to inform future policies that could prevent further damage to the ecosystem.”