REPRODUCTIVE MODES Live birth has evolved from egg-laying ancestors multiple times independently. The European common lizard, _Zootoca vivipara_ (pictured here), is a rare example of a

vertebrate with populations that are either egg-laying or live-bearing. Hybrids resulting from crosses between egg-laying and live-bearing lizards provide the opportunity to explore the

genetic basis of pregnancy. See Recknagel et al. Image credit: Rasmus Holmboe Dahl / Alamy Stock Photo. Cover Design: Allen Beattie.