Climate Change Prematurely Ages Lizards Before They’re Born

As Europe recovers from an unprecedented heat wave that shattered temperature records and melted roads, it’s becoming clear that it isn’t just people who suffer from the effects of climate change—it’s nonhuman animals too. A study published yesterday (August 8) in PNAS, for instance, finds that the heat is aging some lizards prematurely. Researchers noted that lizards that bear live young are giving birth to offspring with shortened telomeres, the strings of DNA that cap chromosomes to protect them from wear and tear. The team suggests that because this gradual degradation of telomeres can be passed across generations, the damage may be difficult to reverse.

“Once you are in this circle of events, it’s quite complicated to come back,” study coauthor Andréaz Dupoué, a biologist at IFREMER, an oceanographic institute in France, tells The Washington Post. “It can become a vicious circle,” which the researchers call an “aging loop.”

The study spent more than a decade focusing on 10 populations of common lizards (Zootoca vivipara, also known as the viviparous lizard) living throughout the Massif Central mountains in France. Over the course of the study, Dupoué and his team collected and analyzed blood and tissue samples from hundreds of individuals. 

The researchers found that those populations living in hotter places were giving birth to offspring with stubbier telomeres; based on the extent of the damage, the team deemed it unlikely that these individuals would survive long enough to reproduce. Typically, these chromosomal caps degrade naturally as an animal ages, the cumulative result of lifelong stress. But previous work has shown that early, prolonged stress can quicken the pace of degradation, resulting in shorter telomeres that are in turn passed on to the next generation.

“The most relevant result of the paper is the detection of a very worrying tendency towards shorter telomeres—and thus, faster aging—in populations exposed to the more demanding climatic conditions for the species,” Germán Orizaola, an evolutionary ecologist at the University of Oviedo in Spain who was not involved in the study, tells the Post, adding that such populations are “at higher risk of extinction.”

During the course of the study, a population that lived in the warmest location the team studied,  an area around Mont Caroux in France, disappeared entirely and is now considered pseudoextinct. “It was quite sad, actually,” Dupoué tells the Post. “It’s something that is really happening at a rapid pace.”

But Dupoué says the results may offer a new marker for judging a population’s stability and whether conservation efforts are having an effect; this is true not just in lizards, but in any species that can be sampled to assess telomere length. “We could just sample the individuals in the populations and diagnose the lengths,” he says, according to the Post. “And we can say, ‘Okay, this one is good; this one is in really bad shape.’”

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