The lizard and the egg: lizards break golden rule of biology

Researchers at The Australian National University (ANU) have made a remarkable discovery about a group of lizards, and how they've managed to thrive in extreme conditions on one of the world's highest mountain ranges. The Liolaemus lizards - found mainly around South America's Andes Mountains - reproduce in a way that challenges one of biology's best known rules, Dollo's Law. PhD candidate Damien Esquerre says as the Andes formed, the lizards evolved to give birth to live young, because eggs struggle to incubate in cold temperatures. Amazingly, when some Liolaemus species moved down to colonise the surrounding lowlands, there's evidence they were able to start laying eggs again. "No mammal has ever re-evolved egg laying, but these lizards seem to. Dollo's Law states that once you lose something it is really hard to regain it. For example, species that adapt to living in caves and lose their eyesight are extremely unlikely to get it back," Mr Esquerre said.