Climate change is sustainable for forest lizards. Due to the increasing heat stress, both individual specimens and the following generations age faster than usual. The reason: The lizards are born with shortened protective caps at the ends of their chromosomes, the telomeres - they are biologically "pre -aged". Above all, dwindling lizard populations are affected. This is reported by a research team around Andréaz Dupoué from the French Université de Bretagne Occidentale in the journal »PNAS«.
The researchers examined 126 female forest lizards (Zootoca vivipara) and 231 juveniles from several populations native to the French Massif Central. In the mountainous region, the animals adapted to cold are dealing with increasingly higher temperatures. The scientists found that especially newborn lizards from shrinking populations had extremely short telomeres when they were exposed to severe heat stress. Telomeres are repeating sections of DNA at the ends of chromosomes, which become a little shorter with each cell division - the cell is aging. If the protective caps become too short, cell division stops and the cell eventually dies. Probably, the researchers suspected, only a few of the pre-aged animals would reach a reproductive age. In addition, females with shortened telomeres had fewer offspring than usual for the species.
The team led by Dupoué therefore suspects that the lizards have become a kind of vicious circle through climate change: increasing heat periods stress the reptiles on a biological level - their metabolism would be heated and their cells would share more frequently, which in turn shrank their telomeres faster. The females would inherit their chromosomes to their descendants with the shorter ends. In this way, after and after generations of forest lizards, with increasing telomers and less life expectations. From a certain tipping point, the vicious circle could lead to the collapse of the lizard population and to die out, the scientists conclude. They propose to introduce the telomer lengths as biomarkers in the future: the protective caps could reveal researchers whether ongoing species protection programs are successful.
